ARTICLE | doi:10.20944/preprints202306.0279.v1
Online: 5 June 2023 (08:43:36 CEST)
In August 2022, in the Moscow region, Russia, on a backyard farm, the mortality was observed at chickens and all 45 birds of this farm died or were slaughtered after onset of symptoms within a few days. Paramyxovirus was isolated from diseased birds. Based on the nucleotide sequences of the F and NP gene fragments, the belonging of virus to subgenotype VII.1 AAvV-1 class II was established. The cleavage site of the F gene 109SGGRRQKRFIG119 and T in 546 and 555 position of NP gene, were typical for the velogenic type. The genetically closest NDV isolates were found in Iran. The mean time of death of 10-day-old chicken embryos upon infection with the minimal infectious dose was 52 hours, which is typical for the velogenic pathotype. The virus caused 100% death of six-week-old chickens during oral infection, as well as 100% mortality of all contact chickens, including those located in remote cages, which proves the ability of virus to spread not only by fecal-oral but also by aerosol route. That demonstrates a high level of pathogenicity and contagiousness of the isolated strain for chicken. However, the mice intranasally infected with high doses of the virus had not die.
Subject: Biology And Life Sciences, Immunology And Microbiology Keywords: Bacillus anthracis; pathogenicity factors; genotyping.
Online: 31 August 2021 (11:41:51 CEST)
Bacillus anthracis, the causative agent of anthrax, has two virulence plasmids: pXO1 and pXO2. Plasmid pXO2 carries the genes of an antiphagocytic capsule synthesis. Plasmid pXO1 carries the genes pagA, lef, and cya encoding anthrax toxins, as well as atxA, which encodes the main regulator of pathogenicity factor expression. In the present paper, we evaluated the polymorphism of the pagA, lef, cya, and atxA genes for 85 B. anthracis strains belonging to different evolutionary lineages and canSNP groups and three B. cereus strains possessing pXO1-like plasmids. We found 19 genotypes (GT) strongly correlated with the main evolutionary lineages; they were mainly correlated with the canSNP group within these lines. In some cases, one GT combined the strains of several canSNP groups, and some canSNP groups were divided into several GTs. The most interesting of such cases were 1) the formation of a separate GT by strains of the A.Br.008/009 group isolated in the former USSR; 2) the presence of a unique GT in some American strains of the A.Br.Aust94 group; 3) the division of the A.Br.001/002 group into two subgroups, one of which may be a transitional link to the group A.Br.Ames; 4) the fact that European isolates of the B.Br.CNEVA group and Arctic strains of the B.Br.001/002 group have a common GT.
ARTICLE | doi:10.20944/preprints202311.0241.v1
Subject: Biology And Life Sciences, Animal Science, Veterinary Science And Zoology Keywords: Porcine rotavirus; G5; Virus isolation; Pathogenicity
Online: 3 November 2023 (11:02:46 CET)
(1) Background: Group A rotaviruses (RVAs) are the primary cause of severe intestinal diseases in piglets. Porcine rotaviruses (PoRVs) are widely prevalent in Chinese farms, resulting in significant economic losses to the livestock industry. However, isolation of PoRVs is challenging, and their pathogenicity in piglets is not well understood. (2) Methods: We conduct clinical testing on a farm in Jiangsu Province, China, and isolate strains of porcine rotavirus by continuously passaging on MA104 cells. Subsequently, the pathogenicity of the isolated strain in piglets was investigated.The piglets of the PoRV-infection group were orally inoculated with 1 mL of 1.0 × 106 TCID50 PoRV, whereas those of the mock-infection group were fed with an equivalent amount of DMEM. (3) Results: Fecal samples were collected from 28 piglets, all of which tested positive for RVAs. A G5P genotype porcine rotavirus strain was successfully isolated from one of the positive samples and named RVA/Pig/China/JS/2023/G5P(JS). The genomic constellation of this strain was G5-P-I5-R1-C1-M1-A8-N1-T1-E1-H1. Sequence analysis revealed that the genes VP3, VP7, NSP2, and NSP4 of the JS strain were closely related to human RVAs, whereas the remaining gene segments were closely related to porcine RVAs, indicating a reassortment between porcine and human strains. Furthermore, infection of 15-day-old piglets with the JS strain resulted in a diarrheal rate of 100% (8 of 8) and mortality rate of 37.5% (3 of 8).(4) Conclusion: The isolated G5P  genotype rotavirus strain, which exhibited strong pathogenicity in piglets, may have resulted from recombination between porcine and human strains. It may serve as a potential candidate strain for developing vaccines, and its immunogenicity can be tested in future studies.
ARTICLE | doi:10.20944/preprints202311.0510.v1
Subject: Biology And Life Sciences, Immunology And Microbiology Keywords: MoPCE1; CAP domain; effector; pathogenicity; OsDi19-5
Online: 8 November 2023 (15:52:43 CET)
Rice blast fungus (Magnaporthe oryzae) causes massive yield losses annually worldwide. The fungus secreted bunch of effector proteins target different rice cellular compartments to facilitate its infection. However, most of intensively studied effectors are small secreted proteins with high presence/absence polymorphism in the fungus, and effectors conserved among different species were rarely investigated. In this study, we identified MoPce1, a CAP/PR domain containing protein common in different species, as an important virulence factor from a screening of 145 putative core effectors (PCE). MoPCE1 is required for pathogenicity but not the asexual development. Ectopic expression of MoPCE1sp in ZH11 background compromised the plant resistance. We also found that MoPce1 lacks the conserved cysteine residuals in CAP domain, and is BIC-localized in invasive hyphae and nuclei-localized when ectopically expressed in tobacco leaves and rice protoplasts. These results suggested that MoPce1 may bind novel ligand(s) rather than sterol. Indeed, we found that MoPce1 could interact with OsDi19-5, a transcription factor in rice. We inferred from these results that MoPce1 is required for pathogenicity by suppressing the immune response in rice, likely through the interaction with OsDi19-5.
ARTICLE | doi:10.20944/preprints202112.0391.v1
Subject: Medicine And Pharmacology, Pediatrics, Perinatology And Child Health Keywords: online prediction; CYP21A2; mutation analysis; pathogenicity prediction
Online: 23 December 2021 (12:00:40 CET)
Context: CYP21A2 deficiency represents 95% of congenital adrenal hyperplasia cases (CAH), a group of genetic disorders that affect steroid biosynthesis. The genetic and functional analysis provides critical tools to elucidate complex CAH cases. One of the most accessible tools to infer the pathogenicity of new variants is in silico prediction. Objective: Analyze the performance of in silico prediction tools to categorize missense single nucleotide variants (SNVs) of the CYP21A2. Methods: SNVs of the CYP21A2 characterized in vitro by functional assays were selected to assess the performance of online single and meta predictors. SNVs were tested separately or in combination with the related phenotype (severe or mild CAH form). In total, 103 SNVs of the CYP21A2 (90 pathogenic and 13 neutral) were used to test the performance of 13 single-predictors and four meta-predictors. Results: SNVs associated with the severe phenotypes were well categorized by all tools, with an accuracy between 0.69 (PredictSNP2) and 0.97 (CADD), and Matthews' correlation coefficient (MCC) between 0.49 (PoredicSNP2) and 0.90 (CADD). However, SNVs related to the mild phenotype had more variation, with the accuracy between 0.47 (S3Ds&GO and MAPP) and 0.88 (CADD), and MCC between 0.18 (MAPP) and 0.71 (CADD). Conclusion: From our analysis, we identified four predictors of CYP21A2 pathogenicity with good performance. These results can be used for future analysis to infer the impact of uncharacterized SNVs' in CYP21A2.
ARTICLE | doi:10.20944/preprints202106.0410.v1
Subject: Biology And Life Sciences, Anatomy And Physiology Keywords: highly pathogenic avian influenza viruses, pathogenicity factors.
Online: 15 June 2021 (14:29:26 CEST)
The H7 subtype of avian influenza viruses (AIV) stands out among other AIV. The H7 viruses cir-culate in ducks, poultry, equine and have repeatedly caused outbreaks of disease in humans. In or-der to study the pathogenicity factors of H7N1 viruses, several variants were obtained, starting with laboratory strain, with a history of 12 passages through chicken embryos. This strain, A/chicken/Rostock/R0p/1934(H7N1) (R0p) had only 3 substitution in HA relatively A/Chicken/Rostock/45/34(H7N1), substitution Arg140Gly among them. 10 variants of this strain was obtained and studied to ascertain its biological property, genome stability and factors of patho-genicity. Strain R0p had decreased virulence for chicken, comparing with described in literature virulence of A/FPV Rostock/34 and A/chicken/Rostock/34 viruses. After 10 passages through the chicken lungs variant was obtained much more pathogenic than the starting R0p. The study of in-termediate passages through the chicken lungs showed that the jump in pathogenicity had occurred sharply between the fifth and sixth passage. By cloning these variants, a pair of strains (R5p and R6p) were obtained, and the complete genomes of these strains were sequenced. Single amino acid substitution was revealed, namely reversion Gly140Arg in HA1. This amino acid is located at the head part of the hemagglutinin, adjacent to the receptor-binding site. In addition to the increased pathogenicity for chicken and mice, R6p differs from R5p in the pattern of foci in cell culture and an increased affinity for a negatively charged receptor analogue, while maintaining a pattern of recep-tor binding specificity and the pH optimum of the HA conformational change.
Subject: Biology And Life Sciences, Virology Keywords: highly pathogenic avian influenza viruses, pathogenicity factors.
Online: 10 May 2021 (14:22:23 CEST)
The H7 subtype of avian influenza viruses (AIV) stands out among other AIV. H7 viruses circulate in ducks, poultry, equine and have repeatedly caused outbreaks of disease in humans. In order to study the pathogenicity factors of H7N1 viruses, several laboratory variants of the A/FPV/Rostock/34 (H7N1) strain were obtained by passages in the chicken lungs. After 10 such passages, a variant was obtained that differed from the parent virus by amino acid substitutions Val109Phe in PB2, Gln621Lys in PB1, Thr32Ala and Leu586Phe in PA Gly140Arg in HA1 and Ala101Thr in HA2 (numbering by H3), Ser82Arg in M2, Arg118Lys and Met124Arg in NS1. No differences were found in proteins NA, NP, M1 and NS2. The resulting variant was hundreds of times more pathogenic for chickens than the original laboratory variant of the virus. The study of intermediate passages showed that the jump in pathogenicity occurs sharply between the fifth and sixth passage through the chicken lungs. By cloning these variants, a pair of strains (R5p and R6p) were obtained, and the complete genomes of these strains were sequenced. Single amino acid substitution was revealed, namely Gly140Arg in HA1. It is important to emphasize that this substitution is a reversion, since Arg is located in position 140 HA1 of original the A/FPV/Rostock/34 (H7N1) virus (GenBank). This amino acid is located at the head part of the hemagglutinin, adjacent to the receptor-binding site. In addition to the increased pathogenicity, R6p differs from R5p by an increased affinity for a negatively charged receptor analogue, an increased affinity for MDCK cells, while maintaining a receptor specificity profile.
REVIEW | doi:10.20944/preprints202005.0487.v1
Subject: Medicine And Pharmacology, Epidemiology And Infectious Diseases Keywords: coronavirus; COVID-19; coronavirus etiology; coronavirus pathogenicity
Online: 31 May 2020 (18:16:48 CEST)
Coronavirus Disease 2019 (COVID-19) is a respiratory illness caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). It is considered to be first reported from Wuhan, Hubei Province, China in December 2019. As of present, there are over 3.7 million identified cases worldwide and more than 259,000 deaths have been reported. This disease, its incubation period, course, complications, and the basis of spread remains a potential question due to variation in the pattern of spread around the globe and relatively fewer number of large-scale studies at present. This literature review aims to study the available data on its spread and incubation period. A literature search using PubMed with regular keywords ‘coronavirus’ and ‘COVID-19’, and Medical Subject Headings (MeSH) search for their etiology and pathogenicity was done with the search builder. The literature search revealed 26,689 studies among which 14 studies were selected for review. Studies were selected after the application of inclusion criteria and exclusion criteria with the removal of duplicates, and careful review for the outcome of interest ‘incubation period’. Among the 14 studies selected for review, there were eight review articles, five case reports, and one comparative study. The current literature review concludes that the mean incubation period for most of the literature falls between five days to 12 days with minimum reported time from known exposure to the onset of a symptom being one day and the maximum reported time from exposure to the onset of a symptom being 18 days.
ARTICLE | doi:10.20944/preprints202001.0160.v1
Subject: Biology And Life Sciences, Virology Keywords: rabies; uDISCO; 3D imaging; rabies pathogenicity; astrocyte infection
Online: 16 January 2020 (08:52:30 CET)
Although conventional immunohistochemistry for neurotropic Rabies virus (RABV) usually shows a high preference for neurons, non-neuronal cells are also potential target cells and abortive infection of astrocytes is considered a main trigger of innate immunity in the CNS. While in vitro studies indicated differences between field and less virulent lab-adapted RABVs, a systematic and quantitative comparison of astrocyte tropism in vivo is lacking. Here, a recently developed solvent-based tissue clearing technique was used to measure the RABV cell tropism in infected brains. Immunofluorescence analysis of 1 mm-thick tissue slices enabled 3D segmentation and quantification of infection frequencies of astrocytes and neurons. Comparison of highly virulent street virus clones from fox, dog, and raccoon with three lab strains of intermediate and low virulence revealed remarkable differences in the ability to infect astrocytes in vivo. While all viruses and infection routes led to comparable neuron infection frequencies, striking differences were detected for the infection of astrocytes. Consistent and inoculation route-independent astrocyte infection by field viruses, together with route-dependent or undetectable astrocyte infection by lab-adapted or vaccine viruses strongly suggests a model in which the ability to establish productive astrocyte infection in vivo functionally distinguishes field and attenuated lab RABV strains.
REVIEW | doi:10.20944/preprints201901.0158.v1
Subject: Medicine And Pharmacology, Dentistry And Oral Surgery Keywords: sialidase; sialic acid; sialoglycoprotease; pathogenicity; therapeutic target; siglec
Online: 16 January 2019 (08:49:16 CET)
Periodontitis is a chronic inflammatory disease affecting the tissues that surround and support the teeth. In the U. S., approximately 65 million people are affected by this condition. Its occurrence is also associated with many important systemic diseases such as cardiovascular disease, rheumatoid arthritis, and Alzheimer’s disease. Among the most important etiologies of periodontitis is Porphyromonas gingivalis, a keystone bacterial pathogen. Keystone pathogens can orchestrate inflammatory disease by remodeling a normally benign microbiota causing imbalance between normal and pathogenic microbiota (dysbiosis). The important characteristics of P. gingivalis causing dysbiosis are its virulence factors that cause effective subversion of host defenses to its advantage , allowing other pathogens to grow. However, the mechanisms involving these processes are poorly understood. However, various microbial strategies target host sialoglycoproteins for immune dysregulation. In addition, the enzymes that break down sialoglycoproteins/sialoglycans are the “sialoglycoproteases”, resulting in exposed terminal sialic acid. This process could lead to pathogen-toll like receptor (TLR) interactions mediated through sialic acid receptor–ligand mechanisms. By assessing the function of P. gingivalis sialoglycoproteases, could pave the way to designing carbohydrate analogues and sialic acid mimetics to serve as drug targets.
ARTICLE | doi:10.20944/preprints202308.0481.v1
Subject: Biology And Life Sciences, Agricultural Science And Agronomy Keywords: Camellia sinensis; Discula theae-sinensis; Colletotrichum; pathogenicity; Co-inoculation
Online: 7 August 2023 (10:01:17 CEST)
Anthracnose is one of primary diseases in tea plants that affects tea yield and quality. The geographical distribution, occurrence regularity, and agronomic measures of tea plants with anthracnose have been researched for decades. However, the pathogenic cause of anthracnose in tea plants is diverse in different regions of the world. Identifying the specific pathogenic fungi causing tea anthracnose is an essential control measure to mitigate this disease. In this study, 88 Diaporthales and 45 Colletotrichum isolates were obtained from 3 different types of diseased tea leaves. Based on multilocus phylogenetic and morphological analysis, 3 known species, including Discula theae-sinensis, Diaporthe ueckerae, Diaporthe lithocarpus, and 3 indistinguishable species of Diaporthales were identified. In adddition, 8 known species of Colletotrichum, C. fructicola, C. camelliae, C. aenigma, C. siamense, C. henanense, C. karstii, C. tropicicola, C. gigasporum, were identified. This study is the first to report C. tropicicola and C. gigasporum in tea plant in China. Discula theae-sinensis was the most common species in this study and caused disease lesions around wounded areas of tea leaves. The dual trials in vitro indicated Discula theae-sinensis and Colletotrichum were slight inhibition. Co-inoculating Discula theae-sinensis and C. fructicola was superior to single inoculation at low concentration.
ARTICLE | doi:10.20944/preprints202306.1363.v1
Subject: Biology And Life Sciences, Insect Science Keywords: Baculoviridae; bioinsecticide; genotypic variant; pathogenicity; virulence; occlusion body production
Online: 19 June 2023 (13:23:00 CEST)
Outbreaks of Anticarsia gemmatalis (Hübner, 1818) (Lepidoptera: Erebidae), a major pest of soybean, can be controlled below economic thresholds with methods that do not involve the application of synthetic insecticides. Formulations based on natural isolates of the Anticarsia gemmatalis multiple nucleopolyhedrovirus (AgMNPV) (Baculoviridae: Alphabaculovirus), played a significant role in integrated pest management programs in the early 2000s, but a new generation of chemical insecticides and transgenic soybean, have displaced AgMNPV-based products over the past decade. However, the marked genotypic variability present among and within alphabaculovirus isolates suggests that highly insecticidal genotypic variants can be isolated and used to reduce virus production costs or overcome isolate-dependent host resistance. This study aimed to select novel variants of AgMNPV with suitable insecticidal traits that could comple-ment the existing AgMNPV active ingredients. Three distinct AgMNPV isolates were compared by restriction endonuclease profile and in terms of their occlusion body (OB) pathogenicity. One isolate was selected (AgABB51) from which eighteen genotypic variants were plaque purified and characterized in terms of their insecticidal properties. The five most pathogenic variants varied in OB pathogenicity although none of them was faster-killing or had higher OB production characteristics than the wild-type isolate. We conclude that the AgABB51 wild-type isolates ap-pear to be genotypically structured for fast speed-of-kill and high OB production, both of which would favor transmission. Interactions among the component variants are likely to influence this insecticidal phenotype.
ARTICLE | doi:10.20944/preprints202301.0404.v1
Subject: Biology And Life Sciences, Virology Keywords: Omicron variant; Infectivity; Pathogenicity; Biothermodynamics; COVID-19; Viral evolution
Online: 23 January 2023 (08:53:40 CET)
The SARS-CoV-2 Hydra with many heads (variants) has been causing the COVID-19 pandemic for 3 years. The appearance of every new head (SARS-CoV-2 variant) causes a new pandemic wave. The last in the series is the XBB.1.5 “Kraken” variant. In the general public (social media) and in the scientific community (scientific journals), during the last several weeks since the variant has appeared, the question was raised of whether the infectivity of the new variant will be greater. This article attempts to provide the answer. Analysis of thermodynamic driving forces of binding and biosynthesis leads to the conclusion that infectivity of the XBB.1.5 variant could be increased to a certain extent. The pathogenicity of the XBB.1.5 variant seems to be unchanged compared to the other Omicron variants.
BRIEF REPORT | doi:10.20944/preprints202005.0466.v1
Subject: Biology And Life Sciences, Virology Keywords: COVID-19; SARS-CoV-2; variant; low pathogenicity; Singapore
Online: 29 May 2020 (12:47:07 CEST)
Number of confirmed cases of COVID-19 caused by SARS-CoV-2 exceeded 5 million as of May 21, 2020. Global average of the case fatality rate of COVID-19 is about 7% so far. There exist variations in case fatality rates among countries. Particularly, Singapore and Qatar have exceptionally low case fatality rates with 0.1% while France’s rate is almost 20%. Since no magic bullet treatment for COVID-19 exists, we investigated SARS-CoV-2 strains specific to Singapore in this study to identify a clade with low pathogenicity. Variant analysis revealed that a clade with variants ORF1ab L3606F, A4489V, S2015R, T2016K, and N P13L is common in Singapore. Based on our analysis of variants and historical case statistics, the clade is dominant in a recent surge. Therefore, we suggest that low case fatality rate of Singapore possibly is attributed to the clade. Although contribution of each variant to the low pathogenicity is not clear, L3606F alone does not accomplish such low pathogenicity from the comparison with case fatality data from Japan, where L3606F is dominant. Further investigation is necessary to conclude to validate this finding.
REVIEW | doi:10.20944/preprints202307.1720.v1
Subject: Biology And Life Sciences, Food Science And Technology Keywords: Fusarium spp.; Fusarium dry rot of potato; pathogenicity; mycotoxin; control
Online: 26 July 2023 (09:43:00 CEST)
Fusarium dry rot is one of the major postharvest potato diseases of during storage after harvest, which not only results in quality degradation but also brings up huge economic losses. The dis-ease can be elicited by some species of Fusarium, the pathogenic fungi of Fusarium causing potato dry rot are considerably diverse in various countries and regions. Fusarium spp. infection is as-sociated with dry rot produce mycotoxins, which has phytotoxicity and mycotoxicoses on hu-mans and animals. Chemical synthetic fungicide is considered as the main control measure to Fusarium dry rot of potato, nevertheless, it is unfortunate that the persistent application inevitably results in the emergency of resistant strain and environmental contamination. A comprehensive disease control strategy includes potato cultivar selection, appropriate cultural practices (crop rotation, cultivate pattern, fertilization, and irrigation), harvesting process and postharvest treatment (harvesting, classification, packaging, wound healing), storage condition (environ-mental disinfection, temperature, humidity and gas composition) along with the application of fungicide pre-harvest or postharvest. Recently, emerging studies indicated that eco-friendly strategies include physical control, chemical methods (such as the application of generally rec-ognized as safe (GRAS) compounds or chemical (elicitors) and biological control have been in-troduced to combat Fusarium dry rot of potato.
ARTICLE | doi:10.20944/preprints202301.0327.v1
Subject: Biology And Life Sciences, Virology Keywords: COVID-19; variant of concern; infectivity; pathogenicity; evolution; Gibbs energy
Online: 18 January 2023 (08:40:33 CET)
SARS-CoV-2 resembles the ancient mythical creature Hydra. Just like with the Hydra, when one head is cut, it is followed by appearance of two more heads, suppression of one SARS-CoV-2 variant causes appearance of newer variants. Unlike Hydra that grows identical heads, newer SARS-CoV-2 variants are usually more infective, which can be observed as time evolution of the virus at hand, which occurs through acquisition of mutations during time. The appearance of new variants is followed by appearance of new COVID-19 pandemic waves. With the appearance of new pandemic waves and determining of sequences, in the scientific community and general public the question is always raised of whether the new variant will be more virulent and more pathogenic. The two variants characterized in this paper, BA.5.2 and BF.7, have caused a pandemic wave during the late 2022. This paper gives full chemical and thermodynamic characterization of the BA.5.2 and BF.7 variants of SARS-CoV-2. Having in mind that Gibbs energy of binding and biosynthesis represent the driving forces for the viral life cycle, based on the calculated thermodynamic properties we can conclude that the newer variants are more infective than earlier ones, but that their pathogenicity has not changed.
REVIEW | doi:10.20944/preprints202208.0036.v1
Subject: Biology And Life Sciences, Immunology And Microbiology Keywords: Listeria ivanovii; pathogenicity; virulence characters; environmental distribution; occurrence in food
Online: 2 August 2022 (04:41:19 CEST)
Listeria ivanovii and L. monocytogenes, are the only pathogenic species of the genus Listeria and share many virulence factors and mechanisms of pathogenicity. L. ivanovii shows host tropism towards small ruminants and rodents and much lower virulence for humans compared to L. monocytogenes. However, severe infections caused by L. ivanovii, resulting in bacteremia, abortion and stillbirth, occasionally occurred in immunocompromised persons and in pregnant women, while in immunocompetent hosts L. ivanovii can cause gastroenteritis. In this review the updated knowledge on virulence aspects and distribution of L. ivanovii in the environment and in food are summarized. Recent research on its virulence characters at genome level gave indications on how pathogenicity evolved in this bacterial species. As for L. monocytogenes, L. ivanovii infections occur after the ingestion of contaminated food, so an overview of reports regarding its distribution in the food products was carried out to obtain indications on the categories of foods exposed to contamination by L. ivanovii. It was found that a wide variety of food products can be a source of this microorganism and that, like L. monocytogenes, L. ivanovii is able to persist in the food production environment. Studies on its ability to grow in enrichment and isolation media suggested that its occurrence in nature might be underestimated. Moreover, virulence varies among strains for differences in virulence character regulation, presence/absence of genetic regions and the possible instability of a Listeria pathogenicity genomic island, LIPI-2, which is unique to L. ivanovii. We can conclude that L. ivanovii, as a possible pathogen for animals and humans, requires more focused investigations regarding its occurrence in the environment and in food and on intra-species variability of pathogenic potential.
ARTICLE | doi:10.20944/preprints202310.0160.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: Colletotrichum higginsianum; DHN-melanin; polyketide synthase (Pks); trihydroxynaphthalene reductase (Thr1); pathogenicity
Online: 4 October 2023 (07:40:06 CEST)
Colletotrichum higginsianum is a major pathogen causing anthracnose in Chinese flowering cabbage (Brassica parachinensis), posing a significant threat to the Chinese flowering cabbage industry. The conidia of C. higginsianum germinate and form melanized infection structures called appressoria, which enable penetration of the host plant's epidermal cells. However, the molecular mechanism underlying melanin biosynthesis in C. higginsianum remains poorly understood. In this study, we identified two enzymes related to DHN-melanin biosynthesis in C. higginsianum: ChPks and ChThr1. Our results demonstrate that the expression levels of genes ChPKS and ChTHR1 were significantly up-regulated during hyphal and appressorial melanization processes. Furthermore, knockout of the gene ChPKS resulted in a blocked DHN-melanin biosynthetic pathway in hyphae and appressoria, leading to increased sensitivity of the ChpksΔ mutant to cell wall interfering agents as well as decreased turgor pressure and pathogenicity. It should be noted that although the Chthr1Δ mutant still exhibited melanin accumulation in colonies and appressoria, its sensitivity to cell wall interfering agents and turgor pressure decreased compared to wild-type strains; however, complete loss of pathogenicity was not observed. In conclusion, our results indicate that DHN-melanin plays an essential role in both pathogenicity and cell wall integrity in C. higginsianum. Specifically, ChPks is crucial for DHN-melanin biosynthesis while deficiency of ChThr1 does not completely blocked melanin production.
ARTICLE | doi:10.20944/preprints202309.2050.v1
Subject: Biology And Life Sciences, Parasitology Keywords: anaerobic parasites; pathogenicity; cell communication; cadherins; high-resolution SEM; Trichomonas adhesion.
Online: 3 October 2023 (03:48:46 CEST)
Trichomonas vaginalis is an extracellular parasite protozoan that causes human trichomoniasis, a sexually transmitted infection (STI) that affects approximately 200 million people worldwide. The presence of T. vaginalis adhesion to inert substrates has been described in several reports. Still, very few studies on cluster formation and more detailed analyses of the contact regions between the membranes of the parasites in these aggregate formations have not been carried out. We analyzed the formation of parasite monolayers and clusters using high-resolution scanning electron microscopy, transmission electron microscopy, cytochemistry, TEM tomography, and dye injection. Here, we show the formation of a monolayer of tightly adherent cells, epithelium-like, when the parasites are in contact with an inert material. Based on this observation, we analyzed whether this monolayer behaves as an epithelium, analyzing cell junctions, cell communication, and ultrastructural aspects. We also analyzed the cluster formation and the morphological characteristics of parasite aggregation observed in the culture supernatant. We report that monolayer formation differs from cluster formation in many aspects. The monolayers form strong adhesion, whereas the clusters have fragile attachments. There is no fusion or passage of molecules between neighbor-attached cells; there is no need for different strains to form filopodia, cytonemes, and extracellular vesicles during cluster formation.
REVIEW | doi:10.20944/preprints202012.0663.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: COVID-19; SARS-CoV-2; interactome; ciliary-flagellar dysfunction; infertility; pathogenicity
Online: 25 December 2020 (13:18:03 CET)
Coronavirus Disease-2019 (COVID-19) is an infectious disease caused by the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). There is sufficient experimental evidence to confirm that SARS-CoV-2 infection produces states of ciliary and flagellar dysfunction. However, these studies are unable to explain the observed effects molecularly, because they lack a sufficient understanding of the interaction between human proteins and virus proteins. Using the physical-chemical study of the human interactome in interaction with the SARS-CoV-2 proteome, we found evidence of interactions to explain the experimental effects from a molecular perspective. We found that ten viral proteins interact with key components in the maintenance of the molecular structure of axoneme. Additionally, we evaluated the pulmonary and extrapulmonary pathogenesis of COVID-19 from the point of view of ciliary dysfunction, and warned about other possible complications such as episodes of transient infertility that, due to the limitations of our work, would need verification.
ARTICLE | doi:10.20944/preprints202007.0719.v1
Subject: Biology And Life Sciences, Virology Keywords: SARS-CoV-2; long-term; neutralization antibody; lymphocyte functionality; viral pathogenicity.
Online: 30 July 2020 (12:16:21 CEST)
COVID-19 patients can recover with a median SARS-CoV-2 clearance of 20 days post initial symptoms (PIS). However, we observed some COVID-19 patients with existing SARS-CoV-2 for more than 50 days PIS. This study aimed to investigate the cause of viral clearance delay and the infectivity in these patients. Demographic data and clinical characteristics of 22 long-term COVID-19 patients were collected. SARS-CoV-2 nucleic acid, peripheral lymphocyte count, and functionality were assessed. SARS-CoV-2-specific and neutralization antibodies were detected, followed by virus isolation and genome sequencing. The median age of the studied cohort was 59.83±12.94 years. All patients were clinically cured after long-term SARS-CoV-2 infection ranging from 53 to 112 days PIS. Peripheral lymphocytes counts were normal. Interferon gamma (IFN-ƴ)-generated CD4+ and CD8+ cells were normal as 24.68±9.60% and 66.41±14.87%. However, the number of IFN-ƴ-generated NK cells diminished (58.03±11.78%). All patients presented detectable IgG, which positively correlated with mild neutralizing activity (ID50=157.2, P=0.05). SARS-CoV-2 was not isolated, and a cytopathic effect was lacking. Only three synonymous variants were identified in spike protein coding regions. In conclusion, decreased IFN-γ production by NK cells and low neutralizing antibodies might favor SARS-CoV-2 long-term existence. Further, low viral load and weak viral pathogenicity was observed in COVID-19 patients with long-term SARS-CoV-2 infection.
ARTICLE | doi:10.20944/preprints202003.0361.v1
Subject: Medicine And Pharmacology, Clinical Medicine Keywords: COVID-19; SARS-CoV-2; pathogenicity model; diagnosis; progression prediction; poikilosis
Online: 24 March 2020 (14:43:24 CET)
A novel strategy is presented for reliable diagnosis and progression prediction of diseases with special attention to COVID-19 pandemy. A plan is presented for how the model can be implemented worldwide in healthcare and how novel treatments and targets can be detected. The idea is based on poikilosis, pervasive heterogeneity and variation at all levels, systems and mechanisms. Poikilosis in diseases can be taken account in pathogenicity model, which is based on distribution of three independent condition measures – extent, modulation and severity. Pathogenicity model is a population or cohort-based description of disease components. Evidence-based thresholds can be applied to the pathogenicity model and used for diagnosis as well as for early detection of patients in risk of developing the most severe forms of the disease. Analysis of patients with differential course of disease can help in detecting biomarkers of diagnostic and prognostic significance. A practical and feasible plan is presented how the concepts can be implemented in practice. Collaboration of many actors, including the World Health Organization and national health authorities, will be essential for success.
ARTICLE | doi:10.20944/preprints202306.0404.v1
Subject: Biology And Life Sciences, Animal Science, Veterinary Science And Zoology Keywords: Chicken infectious anemia virus; isolation and identification; pathogenicity; whole genome; bioinformatics analysis
Online: 6 June 2023 (08:05:07 CEST)
Chicken infectious anemia (CIA) poses a significant threat to the chicken industry in China. De-spite its non-specific symptoms, the disease is often overlooked. This study aimed to conduct a comprehensive analysis of the etiology and pathology of CIA in Guangxi Province, China. Three strains of the chicken infectious anemia virus (CIAV) were isolated from liver samples of diseased 20-week-old chickens. The complete genomes of these strains were sequenced, and experiments on specific pathogen-free (SPF) chicks revealed that the GX21121 strain exhibited high virulence. Histopathological examination of the deceased chicks showed liver cell necrosis, fibrous-serous exudation, inflammatory cell infiltration, hemorrhage in liver tissues, as well as congestion in lung and renal tissues. Phylogenetic analysis of the genome revealed that the three strains had a close genetic relationship to the Heilongjiang wild-type (GenBank KY486144). The genetic evolu-tion of their VP1 genes indicated that all three CIAV isolates belonged to genotype IIIc. In sum-mary, this study demonstrated the genomic diversity of three CIAV strains in adult layer hens. The isolation and characterization of the GX21121 strain as a highly virulent isolate provide val-uable information for further investigations into the etiology, molecular epidemiology, and viral evolution of CIAV.
ARTICLE | doi:10.20944/preprints202110.0287.v1
Subject: Biology And Life Sciences, Plant Sciences Keywords: anthracnose; genome sequencing; pathogenicity factors; Colletotrichum truncatum; Colletotrichum orchidearum; Glomerella; Glycine max
Online: 20 October 2021 (10:11:06 CEST)
Colletotrichum is one of the most important plant pathogenic genera of fungi due to its scientific and economic impact. Colletotrichum spp. can infect a wide range of hosts, causing losses in crops of major importance worldwide, such as soybean. In the past, soybean anthracnose was mainly caused by C. truncatum, but during the last decade, other species have been identified at an increasing rate, becoming one of the most important limiting factors to soybean production in several regions. To gain a better understanding of the evolutionary origin of soybean anthracnose, we compared the repertoire of effector candidates of four Colletotrichum species pathogenic to soybean and eight pathogens of other hosts. Our results show that the four species infecting soybean belong to two lineages and do not share any of the lineage specific effector candidates identified. These results strongly suggest that two Colletotrichum lineages have acquired the capability to infect soybean independently. This study also provides, for each lineage, a set of candidate effectors encoding genes that may have important roles in pathogenicity towards soybean offering a new resource useful for further research on soybean anthracnose management.
ARTICLE | doi:10.20944/preprints201909.0323.v1
Subject: Medicine And Pharmacology, Veterinary Medicine Keywords: clade 18.104.22.168c h5n1 virus; immunity evasion; ha trimer stability; thermostability; mammalian pathogenicity
Online: 29 September 2019 (05:21:52 CEST)
Since 2007, highly pathogenic clade 2.3.2 H5N1 avian influenza A [A(H5N1)] viruses have evolved to clade 22.214.171.124a, b and c, and currently only 126.96.36.199c A(H5N1) viruses circulate in wild birds and poultry. During antigenic evolution, clade 188.8.131.52a and c A(H5N1) viruses acquired both S144N and V223I mutations around the receptor binding site of hemagglutinin (HA), with S144N generating an N-glycosylation sequon. We introduced single or combined reverse mutations, N144S and/or I223V, into the HA gene of clade 184.108.40.206c A(H5N1) virus and generated PR8-derived, 2 + 6 recombinant A(H5N1) viruses. When we compared replication efficiency in embryonated chicken eggs, mammalian cells and mice, the recombinant virus containing both N144S and I223V mutations showed increased replication efficiency in avian and mammalian hosts and pathogenicity in mice. The N144S mutation significantly decreased avian receptor affinity and egg white inhibition, but not all mutations increased mammalian receptor affinity. Interestingly, the combined reverse mutations dramatically increased the thermostability of HA. Therefore, the adaptive mutations possibly acquired to evade avian immunity may decrease viral thermostability as well as mammalian pathogenicity.
ARTICLE | doi:10.20944/preprints202311.1514.v1
Subject: Biology And Life Sciences, Plant Sciences Keywords: Fusarium spp.; genetic diversity; pathogenicity; phylogenetic analyses; resistance; root rot; Sanger sequencing; soybean
Online: 23 November 2023 (11:06:49 CET)
Fusarium spp. are commonly associated with the root rot complex of soybean (Glycine max). Previous surveys identified six common Fusarium species from Manitoba, including F. oxysporum, F. redolens, F. graminearum, F. solani, F. avenaceum and F. acuminatum. This study aimed to determine their pathogenicity, assess host resistance and evaluate the genetic diversity of Fusarium spp. isolated from Canada. Pathogenicity was tested on two cultivars, ‘Akras’ (moderate resistance) and ‘B150Y1’ (susceptible), under greenhouse conditions. The virulence of the fungal isolates varied, with root rot severities ranging from 1.5 to 3.3 on a 0-4 scale. The six species were used to screen a panel of 20 Canadian soybean cultivars for resistance in a greenhouse. Cluster and principal component analyses were conducted based on the same traits as for the pathogenicity study. Two of the cultivars, ‘P15T46R2’ and ‘B150Y1’, were consistently found to be tolerant to F. oxysporum, F. redolens, F. graminearum and F. solani. To investigate the incidence and prevalence of Fusarium spp. in Canada, fungi were isolated from 106 soybean fields surveyed across Manitoba, Saskatchewan, Ontario and Quebec. Two-hundred twenty-one Fusarium isolates were identified, with phylogenetic analyses indicating diversity of the isolates in the major soybean production regions of Canada.
REVIEW | doi:10.20944/preprints202308.2167.v1
Subject: Biology And Life Sciences, Virology Keywords: SARS-CoV-2; 1918 H1N1 influenza virus; immune escape; upper respiratory tract; pathogenicity
Online: 31 August 2023 (10:06:29 CEST)
Omicron variants have higher infectivity, more immune escape but lower risk of severe clinical outcomes than the ancestral variants. However, people are still wondering whether SARS-CoV-2 may become lethal again or whether some highly-pathogenic strain may emerge in the future. Omicron is more selective proliferation in the upper respiratory tract (URT). The temperature of human URT is 33–34°C, and the virus strains other than Omicron cannot replicate effectively at this temperature. While Omicron adapted to the low temperature environment, so its distribution mainly depends on the expression levels of ACE2 in cells. Similar distribution switch from lungs to URT has been observed for the 1918 H1N1 influenza virus, who vanished after 1921 and has been turned to be the seasonal human influenza A viruses. However, some relatively high-pathogenic SARS-CoV-2 strains and influenza-virus strains may still emerge in the future. Dynamic changes in the viral virulence should be monitored constantly.
ARTICLE | doi:10.20944/preprints202308.0616.v1
Subject: Biology And Life Sciences, Biology And Biotechnology Keywords: whey; valorization; fermentation; bio‐ethanol production; probiotic drinks; in‐vitro tolerance; pathogenicity assessment
Online: 8 August 2023 (07:11:26 CEST)
Cheese whey, a significant byproduct of the dairy industry, poses a substantial environmental challenge due to its organic pollutant load and large size demands for effective and affordable valorization methods. The abundance of lactose and other organic compounds in whey contributes to its elevated Biological Oxygen Demand (BOD) and Chemical Oxygen Demand (COD), further straining natural ecosystems. This study aimed to investigate the nutritional potential of whey and its conversion into value-added products: bioethanol and probiotic drinks. To achieve this, Bacillus megaterium and Bacillus subtilis strains, isolated from soil samples in Nepal, were co-cultured with Lactobacillus and Saccharomyces cerevisiae in the whey broth for fermentation. Ethanol distillation was carried out using a Rota-evaporator to maintain the viability of the fermenting organisms within the broth. Moreover, the probiotic criteria of the fermenting strains were extensively examined. Experimental observations revealed a remarkable concentration of 9.2 g/L of ethanol, resulting in an ethanol yield of 0.23 g/L. Extrapolating this rate, it is theoretically possible to produce an annual global bioethanol output of 5 million tons using whey as a sustainable and abundant resource. Furthermore, the study explores novel advancements in the distillation process, demonstrating the successful extraction of ethanol at room temperature. Additionally, the fermentation organisms employed in this research exhibit robust viability, surviving various in-vitro stress-tolerant tests, including exposure to bile salt, pH fluctuations, and gastric juice. These resilient strains also demonstrated long-term stability in fermented whey broth, making them promising candidates for the development of probiotic beverages. This dual approach not only enables the sustainable management of organic waste but also presents an opportunity to create value-added products with positive implications for both the environment and human health.
ARTICLE | doi:10.20944/preprints202309.1964.v1
Subject: Biology And Life Sciences, Virology Keywords: Biothermodynamics; Virus-host interaction; COVID-19; Pandemic; Variant under monitoring; Pathogenicity; Pathogen; August 2023
Online: 28 September 2023 (11:23:34 CEST)
Similarly to a phoenix, SARS-CoV-2 has appeared periodically in waves. The new variants that appeared through mutations have during the 4 years of the pandemic suppressed earlier variants, causing new waves of the pandemic. The Omicron BA.2.86 Pirola variant is the latest in the sequence of SARS-CoV-2 variants, which appeared in 2023. The BA.2.86 variant has started to spread rapidly and we are witnesses of a new epidemic wave. In this short period, an increased infectivity was noticed, which results in rapid spreading and decreased pathogenicity, which results in a lower number of severe cases. However, in the public there is a fear of further development of the epidemic. This analysis was made with the goal to assess the risks in the period of late 2023. Mutations that were developed by the BA.2.86 variant have led to a change in empirical formula and thermodynamic properties. It seems that there is no ground for fear of an extensive spreading of severe forms, but there are reasons for caution and monitoring of the spreading of the epidemic and potential appearance of new mutations.
REVIEW | doi:10.20944/preprints202103.0034.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: respiratory illness; pathogenicity; virulence; natural selection; colds; influenza; rhinovirus; weather; climate; Tropics; summer; winter
Online: 1 March 2021 (17:14:19 CET)
This review seeks to explain four features of viral respiratory illnesses that have perplexed generations of virologists: (1) the seasonal timing of respiratory illness; (2) the common viruses causing respiratory illness worldwide, including year-round disease in the Tropics; (3) the rapid response of outbreaks to weather, specifically temperature; (4) the rapid arrival and termination of epidemics caused by influenza and other viruses. The inadequacy of the popular explanations of seasonality is discussed, and a simple hypothesis is proposed, called Temperature Dependent Viral Tropism (TDVT), that is compatible with the above features of respiratory illness. TDVT notes that viruses can transmit themselves more effectively if they moderate their pathogenicity (thereby maintaining host mobility) and suggests that endemic respiratory viruses accomplish this by developing thermal sensitivity within a range that supports organ-specific viral tropism within the human body, whereby they replicate most rapidly at temperatures below body temperature. This allows them to confine themselves to the upper respiratory tract and to avoid infecting the lungs, heart, gut etc. Biochemical and tissue-culture studies show that “wild” respiratory viruses show such natural thermal sensitivity. The typical early autumn surge of colds and the existence of respiratory illness in the Tropics year-round at intermediate levels are explained by the tendency for strains to adapt their thermal sensitivity to their local climate and season. The TDVT hypothesis has important practical implications for preventing and treating respiratory illness including Covid-19. TVDT is testable with many options for experiments to increase our understanding of viral seasonality and pathogenicity.
HYPOTHESIS | doi:10.20944/preprints202101.0389.v1
Subject: Medicine And Pharmacology, Immunology And Allergy Keywords: respiratory illness; pathogenicity; virulence; natural selection; colds; influenza; rhinovirus; weather; climate; Tropics; summer; winter
Online: 19 January 2021 (16:42:56 CET)
This review seeks to explain four features of viral respiratory illnesses that have perplexed many generations of microbiologists: (1) the seasonal occurrence of viral respiratory illness; (2) the occurrence of respiratory illness year-round in the Tropics; (3) the rapid response of illness to temperature drops in temperate regions; (4) the explosive arrival and rapid termination of epidemics caused by influenza and other respiratory viruses. I discuss the inadequacy of the popular explanations of seasonality, and propose a simple hypothesis, called Temperature Dependent Viral Tropism (TD-VT), that is compatible with the above and other features of respiratory illness. TD-VT notes that viruses can often transmit themselves more effectively if they moderate their pathogenicity (thereby maintaining the mobility of their hosts) and suggests that most endemic respiratory viruses accomplish this by developing thermal sensitivity, in the sense that they normally replicate rapidly only at temperatures below normal body temperature. This allows them to confine themselves to the upper respiratory tract and to avoid infecting the lungs, heart, gut etc. I review biochemical and tissue-culture studies that found that “wild” respiratory viruses often show natural thermal sensitivity within a range that supports organ-specific tropism within the human body, and I discuss the evident tendency for viral strains to adapt their thermal sensitivity to their local climate and season. I also explore the possible misinterpretation of early experiments where volunteers were inoculated nasally with viral samples and then chilled. Next, I discuss the practical implications of the TD-VT hypothesis for preventing and treating respiratory illness. Finally, I note that the hypothesis is very testable and make suggestions for the most important experiments to increase our understanding of the seasonality and pathogenicity of viral respiratory illness.
ARTICLE | doi:10.20944/preprints202305.1551.v1
Subject: Biology And Life Sciences, Agricultural Science And Agronomy Keywords: filamentous growth; jasmonic acid carboxyl methyl transferase (JMT); methyl jasmonate (MeJA); pathogenicity; Sporisorium scitamineum; sugarcane smut
Online: 23 May 2023 (03:41:11 CEST)
Sporisorium scitamineum, the basidiomycetous fungus causing sugarcane smut that leads to severe losses in sugarcane quantity and quality, undergoes sexual mating to form dikaryotic hyphae capable of invading the host cane. Therefore, suppressing dikaryotic hyphae formation would potentially be an effective way to prevent host infection by the smut fungus, and the following disease symptom development. The phytohormone methyl jasmonate (MeJA) has been showed to induce plant defense against insects and microbial pathogens. In this study, we verified that exogenous addition of MeJA suppressed dikaryotic hyphae formation under in vitro culture condition, and effective in inhibiting maize smut disease symptom caused by Ustilago maydis. We constructed an Escherichia coli strain expressing plant JMT gene, encoding a jasmonic acid carboxyl methyl transferase that catalyzes conversion from jasmonic acid (JA) to MeJA. By GC-MS we confirmed that the transformed E. coli strain, designated as pJMT strain, was able to produce MeJA in the presence of JA and S-adenosylmethionine (SAM; as methyl donor). Furthermore, the pJMT strain was able to suppress S. scitamineum filamentous growth under in vitro culture condition. It waits to further optimize JMT expression under field condition, in order to utilize the pJMT strain as a biocontrol agent (BCA) of sugarcane smut disease. Overall, our study provides a potentially novel method for controlling crop fungal diseases by boosting phytohormone biosynthesis.
ARTICLE | doi:10.20944/preprints202002.0022.v1
Subject: Biology And Life Sciences, Virology Keywords: influenza B virus; mammalian adaptation; amino acid substitutions; pathogenicity; influenza model; animal model; virulence; antiviral drugs
Online: 3 February 2020 (06:24:05 CET)
Over the years influenza B virus (IBV) contribute annual disease and can lead to serious respiratory disease among humans. More attention should be paid to the mammalian adaptive processes of B viruses and development of vaccines against current influenza. Because of preclinical trials of anti-influenza drugs are conducted mainly on mice, we developed adequate animal model using antigenically-relevant IBV strain for testing anti-influenza drugs and protective efficacy of flu vaccines. We serially passaged Victoria lineage (clade 1A) IBV 17 times in BALB/c mice. The adaptive amino acid substitutions were found in HA (T214I) and NA (D432N). By the electron microscopic examination, we showed spherical and elliptical shapes of IBV. Light microscopy showed that mouse-adapted B virus caused influenza pneumonia on day 6 post inoculation. We evaluated the illness pathogenicity, viral load and histopathological features of mouse-adapted IBV and estimated anti-influenza drugs and vaccine efficiency in vitro and in vivo. Assessment of investigational anti-influenza drug oseltamivir ethoxisuccinate and flu vaccine Ultrix® revealed effectivity against our mouse-adapted influenza B virus.
BRIEF REPORT | doi:10.20944/preprints202309.1217.v1
Subject: Biology And Life Sciences, Agricultural Science And Agronomy Keywords: Dracaena braunii; Colletotrichum gloeosporioides; internal transcribed spacer (ITS); glyceraldehyde-3-phosphate dehydrogenase (GAPDH); molecular characterization; pathogenicity test
Online: 19 September 2023 (13:29:11 CEST)
Lucky bamboo (Dracaena sanderiana hort. ex Mast. = Dracaena braunii) is a domestic species widely cultivated for ornamental purposes in China. In March 2022, a severe occurrence of anthracnose disease was observed on the stems of lucky bamboo plants in a greenery retail store located in Nanjing, Jiangsu Province, China. The morphological characteristics of isolates obtained from diseased stem tissues were identical with those described for Colletotrichum species. Based on multilocus phylogenetic analysis with the internal transcribed spacer (ITS), actin (ACT) gene, and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) gene, the pathogen was identified as Colleto-trichum gloeosporioides (Penz.) Penz. & Sacc. Pathogenicity was verified by mycelial plug-inoculating stem cuttings of one-year-old lucky bamboo plants and spray-inoculating whole one-year-old lucky bamboo plants, respectively. Koch’s postulates were fulfilled by the re-isolation of C. gloeosporioides from symptomatic tissues. To the best of our knowledge, this report describes the first time that C. gloeosporioides was observed to cause anthracnose on lucky bamboo in China.
REVIEW | doi:10.20944/preprints202304.0555.v1
Subject: Biology And Life Sciences, Immunology And Microbiology Keywords: Gastric Cancer; Helicobacter pylori; cag Pathogenicity Island; Cytotoxin-Associated Gene A; Oncoprotein; Vacuolating Toxin A; Immune Evasion
Online: 19 April 2023 (07:14:39 CEST)
Gastric cancer is a challenging public health concern worldwide and remains a leading cause of cancer-related mortality. The primary risk factor implicated in gastric cancer development is infection with Helicobacter pylori. H. pylori induces chronic inflammation affecting the gastric epithelium, which can lead to DNA damage and promotion of precancerous lesions. Disease manifestations associated with H. pylori are attributed to virulence factors with multiple activities and its capacity to subvert host immunity. One of the most significant H. pylori virulence determinants is the cagPAI gene cluster, which encodes a type IV secretion system and the CagA toxin. This secretion system allows H. pylori to inject the CagA oncoprotein into host cells, causing multiple cellular perturbations. Despite the high prevalence of H. pylori infection, only a small percentage of affected individuals develop significant clinical outcomes, while most remain asymptomatic. Therefore, understanding how H. pylori triggers carcinogenesis and its immune evasion mechanisms is critical in preventing gastric cancer and miti-gating the burden of this life-threatening disease. This review aims to provide an overview of our current under-standing of H. pylori infection, its association with gastric cancer and other gastric diseases, and how it subverts the host immune system to establish persistent infection.
ARTICLE | doi:10.20944/preprints202307.0246.v1
Subject: Biology And Life Sciences, Ecology, Evolution, Behavior And Systematics Keywords: Keywords: Plant–pathogen interactions; Grape trunk diseases; GTD; Botryosphaeria dieback; Pathogenicity; Tissue age, Virulence, Vitis vinifera; Cabernet Sauvignon.
Online: 4 July 2023 (14:05:41 CEST)
In vineyards, Botryosphaeria dieback (BD) occurs in young and old plants. In the field, the prevalence and severity of the disease increase proportionally with the age of the vineyards. Among the pathogens that cause (BD), Diplodia seriata is the most prevalent species in Chile and other countries with a Mediterranean climate. To date, no information is available on the sus-ceptibility of adult wood to infection by this pathogen since most of the pathogenicity tests have been carried out on 1- or 2-year-old shoots or detached canes. Therefore, a pathogenicity test was carried out on plants under field conditions, with inoculations in plants, on one-year-old shoots, and 2- and 10-year-old wood in grapevine cv. Cabernet Sauvignon. A pathogenicity test was carried out with two isolates of D. seriata selected in an assay in detached canes that were 2-year-old. The results on plants showed that D. seriata was significantly more aggressive on 10-year-old than on one- or two-year-old tissue. These results were compared with the lesions ob-tained from two-year-old canes. The results of this work are consistent with the damage ob-served in the field, highlight the importance of identifying each pathogenic species that causes (BD) and contribute to the knowledge of the epidemiology of this disease in Mediterranean cli-mates.
ARTICLE | doi:10.20944/preprints201811.0606.v1
Subject: Biology And Life Sciences, Anatomy And Physiology Keywords: viroid; pathogenicity; RNA silencing; Dicer-like proteins; small interfering RNA; microRNA398; microRNA398a-3p; superoxide dismutase 1; reactive oxygen species; systemic necrosis
Online: 28 November 2018 (06:50:07 CET)
To examine the role of RNA silencing in defense against viroid, a Dicer-like 2 and 4 (DCL2&4)—double knockdown transgenic tomato line 72E was created. The expression of endogenous DCL2 and DCL4 in line 72E decreased to about a half of the empty cassette line EC. When challenged with potato spindle tuber viroid (PSTVd), 72E allowed significantly higher level of PSTVd accumulation early in infection and showed lethal systemic necrosis. The size distribution of PSTVd-derived small RNA was significantly changed: the numbers of 21 and 22 nucleotides (nt) species in line 72E was approximately 66.7% and 5% of those in line EC, respectively. Conversely, the numbers of 24-nt species increased by 1100%. Furthermore, expression of miR398a-3p and miR398 increased 770–868% in the PSTVd-infected 72E, compared to the PSTVd-infected EC. In parallel, superoxide dismutase (SOD1) in PSTVd-infected 72E showed higher expression levels. In concert with miR398a-3p, SOD1 controls detoxification of reactive oxygen species (ROS) generated in cells. Since high levels of ROS production and its scavenging activity were observed in PSTVd-infected 72E, the lack of full-activity of DCLs was thought to have made the plant incapable to control excessive ROS production and thus resulted in to develop lethal systemic necrosis.
ARTICLE | doi:10.20944/preprints202311.0738.v1
Subject: Biology And Life Sciences, Virology Keywords: Influenza A virus; A/South Africa/3626/2013 (H1N1)pdm09; H1N1pdm09 model strain; mutations in polymerase complex and hemagglutinin; pathogenicity; toxicity; immunogenicity
Online: 13 November 2023 (14:17:10 CET)
Influenza virus strain A/South Africa/3626/2013 (H1N1)pdm09 (SA-WT) is a non-mouse-adapted model strain, which has naturally high pathogenic properties for mice. It has been suggested that the high pathogenicity of this strain for mice could be due to the three strain-specific substitutions in the polymerase complex (Q687R in PB1, N102T in PB2, and E358E/K heterogeneity also in PB2). To evaluate the role of these replacements, SA-WT was passaged five times in mouse lungs, and the genome of the mouse-adapted version of the SA-WT strain (SA-M5) was sequenced. SA-M5 lost E358E/K heterogeneity and retained E358, which is the prevalent amino acid at this position among H1N1pdm09 strains. Besides, in the hemagglutinin of SA-M5, two heterogeneous substitutions (G155G/E and S190S/R) were identified. Both viruses, SA-M5 and SA-WT, were compared for their toxicity, ability to replicate, pathogenicity, and immunogenicity for mice. In mice infected with SA-M5 or SA-WT strains, toxicity, virus titer in pulmonary homogenates, and mouse survival did not differ significantly. Contrarily, an increase in the immunogenicity of SA-M5 compared to SA-WT was observed. This increase could be due to the substitutions G155G/E and S190S/R in the HA of SA-M5. The prospects for using SA-M5 in studying the immunogenicity mechanisms were also discussed.
REVIEW | doi:10.20944/preprints202305.1708.v1
Subject: Biology And Life Sciences, Life Sciences Keywords: Cytoplasmic membrane homeostasis; Pathogenicity; Pathogenic fungi; Membrane lipid metabolism; Membrane curvature; Transmembrane protein; Cell wall components; Cytoskeleton; Growth and development; Host infection
Online: 24 May 2023 (10:38:22 CEST)
The cytoplasmic membrane is the fundamental component of all living cells, which participates in various physiological processes, such as material exchange, stress response, cell recognition, signal transduction, cellular immunity, apoptosis, pathogenicity, etc. The normal function of a cytoplasmic membrane requires stable organization of transmembrane protein-lipid microdomains, transmembrane protein-cell wall microdomains, and cytoskeleton-transmembrane protein microdomains. Here, we review the mechanisms and functions of various membrane lipid components, fatty acid content and saturation, membrane curvature, and cell wall and cytoskeleton in plasma membrane homeostasis affecting the pathogenicity of pathogenic fungi. Pathogenic fungi maintains plasma membrane homeostasis and contributes to fungal virulence by maintaining plasma membrane assembly, structural and functional integrity of pathogenic fungi at various stages of cell development through interactions among lipid components of cytoplasmic membranes, transmembrane proteins, cytoskeleton and cell wall components, etc.