The major histocompatibility complex (MHC) genes are the most polymorphic genes in vertebrates, and their proteins play a critical role in adaptive immunity for defense against a variety of pathogens. MHC diversity was lost in many species after experiencing a decline in size. To understand the variation and evolution of MHC genes in the Siberian ibex, Capra sibirica, which has undergone a population decline, we analyzed the variation of the second exon of MHC class II DRB genes in samples collected from five geographic localities in Xinjiang, China, that belong to three diverged mitochondrial clades. Consequently, we identified a total of 26 putative functional alleles (PFAs) with 260 bp in length from 43 individuals, and found one (for 27 individuals) to three (for 5 individuals) PFAs per individual, indicating the presence of one or two DRB loci per haploid genome. The Casi-DRB1*16 was the most frequently occurring PFA, Casi-DRB1*22 came after found in only seven individuals, 14 PFAs occurred once (7 PFAs twice), implying high frequency of rare PFAs. Interestingly, more than half of the (15) PFAs were specific to clade I, only one and three PFAs were specific to clades II and III, respectively. So, we assume that the polygamy and sextual segregation nature of this species likely contributed to the allelic diversity of DRB genes. Genetic diversity indices showed that PFAs of clade II were lower in nucleotide, amino acid, and supertype diversity compared to those of the other two clades. The way of allele sharing and FST values between three clades were to some extent in agreement with pattern observed in mitochondrial DNA divergence. In addition, recombination analyses revealed no evidence for significant signatures of recombination events. Alleles shared by clades III and the other two clades diverged 6 million years ago, and systematic neighbor grids showed cross-species polymorphisms. Together with the PAML and MEME analyses, the results indicated that the DRB gene in C. sibirica evolved under balancing and positive selection. However, by comparison, it can be clearly seen that different populations were under different selective pressures. Our results are valuable in understanding the diversity and evolution of the DRB gene in a mountain living C. sibirica and in making decisions on future long-term protection strategies.

Coronaviruses are highly transmissible and pathogenic viruses for humans and animals. The vast quantity of information collected about SARS-CoV-2 during the pandemic helped to unveil details on the mechanisms behind the infection, which are still largely elusive. Recent research demonstrated that different class I/II human leukocyte antigen (HLA) alleles might define an individual susceptibility to SARS-CoV-2 spreading, contributing to the differences in the distribution of the infection through different populations; additional studies suggested that the homolog of the HLA in cats, the Feline Leukocyte Antigen (FLA), plays a pivotal role in the transmission of viruses. With these premises, this study aimed to exploit a bioinformatic approach for the prediction of the transmissibility potential of two distinct Feline Coronaviruses (FCoVs) in domestic cats (Feline enteric Coronavirus, FeCV and Feline Infectious Peritonitis Virus, FIPV) using SARS-CoV-2 as the reference model. We performed an epitope mapping of nonapeptides deriving from SARS-CoV-2, FeCV and FIPV glycoproteins and predicted their affinities for different alleles included in the three main loci in class I FLAs (E, H and K). The predicted complexes with the most promising affinities were then subjected to molecular docking and molecular dynamics simulations to provide insights into the stability and binding energies in the cleft. Results showed the FLA proteins encoded by alleles in FLA-I H (H*00501 and H*00401) and E (E*01001 and E*07001) loci are largely responsive to several epitopes deriving from replicase and spike proteins of the analyzed coronaviruses. The analysis of the most affine epitope sequences resulting from the prediction can stimulate the development of anti-FCoV immunomodulatory strategies based on peptide drugs.

Purpose Immune responses for cancer cells can be altered according to genetic variation of human leukocyte antigen (HLA). Association of HLA polymorphism with risk of various cancer types is well known. However, the association between HLA and glioblastoma (GBM) remains uncertain. We sought to evaluate the association of HLA polymorphism with risk of GBM development in Koreans. Materials and Methods A case-control study was performed to identify the odds ratios (OR) of HLA class I and II genes for GBM. The control group consisted of 142 healthy Korean volunteers, and the GBM group was 80 patients with newly diagnosed GBM at our institution. HLA class I (-A, -B, and –C) and class II (-DR, -DQ, and –DP) genotyping was performed by high-resolution polymerase chain reaction (PCR)-sequence-based typing (PCR-SBT) methods. Results There were significantly decreased frequencies of HLA-A*26:02 (OR 0.22 CI 0.05-0.98), HLA-C*08:01 (OR 0.29 CI 0.10-0.87), and HLA-DRB1*08:03 (OR 0.32 CI 0.11-0.98), while there was significantly increased frequency of HLA-C*04:01 (OR 2.29 CI 1.05-4.97). In analysis of haplotypes, the frequency of DRB1*14:05-DQB1*05:03 was significantly decreased (OR 0.22 CI 0.05-0.98). Conclusion This study suggests that genetic variations of HLA may affect GBM development in Koreans. Further investigations with larger sample sizes are needed to delineate any potential role of the HLA polymorphisms in the pathogenesis of GBM development.

Coronavirus disease (COVID-19) is a new discovered strain where WHO officially declares the disease as COVID-19 while the virus responsible for it called Severe Acute Respiratory Syndrome Coronavirus 2 or SARS-CoV-2. The incubation period of this disease is between 14 days. Ordinary clinical symptoms that reported around the world include fever, cough, fatigue, diarrhoea and vomiting as well as asymptomatic for certain people. Infection is spread mainly through broad droplets. In early March 2020, WHO again has announced that COVID-19 is a pandemic with currently no specific treatment. The potential use of SARS-COV-2 proteome as a vaccine candidate by analysing through B-cell and T-cell antigenicity by using a immunoinformatics approach as a vaccine development early stage. In this study, we used consensus sequence for SARS-COV-2 proteome that was retrieved from NCBI database. VaxiJen 2.0 was mainly used to identify the antigenic property of SARS-COV-2 proteins. IEDB then used to analyse the B-cell epitope, the presence of T cell immunogenic epitope in SARS-COV-2 proteins was obtained by using compromise method of MHC class I and II tools that accessible respectively using ProPred-1 server and MHC II Binding Prediction in IEDB database. The best epitopes of B and T-cell epitopes were predicted with high antigencity and the information is disseminated through web-based database resource (https://covid-19.omicstutorials.com/epitopes/). This study will be useful to find a new epitope-based candidate for SARS-COV-2. However, further study needs to be done for the next stages of vaccine development.

Udder diseases (mastitis) are a serious cause of economic losses in sheep breeding as they have a negative impact on lamb rearing and the quality of dairy products. So far the progress in treatment and prevention of these diseases has been insufficient, giving ground for searching possibilities of using natural immunity to combat mastitis. The aim of the study was to assess the relationship between the microsatellite polymorphism of selected Ovar-MHC genes and the health status of the mammary gland of sheep. The research was carried out on sheep of the Polish Heath and Polish Lowland breeds. In ovine milk the number of somatic cells (SCC) and the percentage of the lymphocyte subpopulation were assessed. On the basis of genomic DNA, molecular analysis of the Ovar-MHC gene fragments (OLADRB1, OLADRB2, OMHC1) polymorphism was performed. Significant differences were found in SCC and the percentage of lymphocytes (CD4, CD8, CD19) in the milk depending on the alleles of the Ovar-MHC genes. Alleles of 488 bp (DRB1) and 284 bp (DRB2) were found more frequently in sheep with healthy udders, while carriers of the 508 bp (DRB1) and 272 bp (DRB2) alleles were more prone to subclinical mastitis. The obtained results justify the need for further research in order to better understanding the genetic basis of mastistis and to search for effective molecular markers that can be used in breeding practice.

The basic pattern of MHC variation in fish, with MHC class I versus class II, and polymorphic classical versus nonpolymorphic nonclassical, is similar in fish and mammals. Nevertheless, in many or all teleost fishes, important differences with mammalian or human MHC were observed: (1) The allelic/haplotype diversification levels of classical MHC class I genes tend to be much higher than in mammals; (2) Teleost fish classical MHC class I and class II loci are not linked. The present article summarizes previous studies that performed quantitative trait loci (QTL) analysis for mapping differences in teleost fish disease resistance, and discusses them from MHC point of view. Overall, those studies suggest the possible importance of genomic regions including classical MHC class II and nonclassical MHC class I genes, whereas similar observations were not made for the genomic regions with the highly diversified classical MHC class I alleles. The present study is a review and discussion of the fish MHC situation.

PCSK9 is implicated in familial hypercholesterolemia via targeting the cell surface PCSK9-LDLR complex toward lysosomal degradation. The M2 repeat in the PCSK9's C-terminal domain is essential for its extracellular function, potentially through its interaction with an unidentified “protein X”. The M2 repeat was recently shown to bind an R-x-E motif in MHC-class-I proteins (implicated in the immune system), like HLA-C, and causing their lysosomal degradation. These findings suggested a new role of PCSK9 in the immune system and that HLA-like proteins could be “protein X” candidates. However, the participation of each member of the MHC-I protein family in this process and their regulation of PCSK9's function have yet to be determined. Herein, we compared the implication of MHC-I-like proteins such as HFE (involved in iron homeostasis) and HLA-C on the extracellular function of PCSK9. Our data revealed that the M2 domain regulates the intracellular sorting of the PCSK9-LDLR complex to lysosomes, and that HFE is a new target of PCSK9 that inhibits its activity on the LDLR, whereas HLA-C enhances its function. This work suggests the potential modulation of the PCSK9 functions through interactions of HFE and HLA-C.

Type 2 diabetes has been linked to the expression of Human Leukocyte Antigens, principally to the major Histocompatibility Complex Class II and only scarce reports to Major Histocompatibility Complex class I in specific populations. The objective of the present work was to explore the presence of polymorphisms in the MHC class I related to Type 2 diabetes in the Mexican population using the GWAS SIGMA database. This database contains information of 3,848 Mexican individuals with type 2 diabetes and 4,366 control individuals from the same population without clinical or hereditary history of the disease. The searching criteria considered a P value < 0.005 and odds ratio, OR > 1.0. Ten novel statistically significant nucleotide variants were identified: four polymorphisms associated with HLA-A (A*03:01:01:01), and six with HLA-C (C*01:02:01:01). These alleles have a high prevalence in Latin American populations and could potentially be associated with autoimmunity mechanisms related with the development of Type 2 diabetes complications.

The bark of Rhus verniciflua Stokes (RVS) is used as a food additive and herbal medicine for various inflammatory disorders and cancer in Eastern Asia. RVS exerted anti-inflammatory effects in lipopolysaccharide (LPS)-stimulated RAW264.7 cells, but whether this effect occurs in macrophages after oral administration has not been determined. We used a thioglycollate-induced peritonitis model to obtain macrophages from mice given RVS. We examined the systemic inflammatory response to intraperitoneal LPS. RVS-treated mice had an increased population of peritoneal exudate cells expressing CD11b and SRA. Increased uptake of Alexa Fluor 488-labeled acetylated lipoprotein was observed in monocyte-derived macrophages from RVS-treated mice. When these cells from the RVS group were stimulated with LPS, the levels of tumor necrosis factor (TNF)- and interleukin (IL)-6 in the supernatant decreased, but the level of IL-12 increased. The surface expression of CD86 was reduced, but surface expression of class II MHC molecules was increased. RVS suppressed the serum levels of LPS-induced TNF- and IL-6. RVS enhanced monocyte differentiation in thioglycollate-induced peritonitis by increasing scavenger receptor expression and activity. Macrophages isolated from mice given RVS responded differently to LPS. These findings demonstrate that RVS confers selective anti-inflammatory activity without causing the overall inhibitory effects on immune cells.

Current theories of autoimmunity are diverse, sometimes contradictory, and suffer from incompleteness. Although substantial evidence exists that adaptive and innate immunity, sex, genetic predisposition, and the microbiome all play essential roles in autoimmune disease etiologies and pathogenesis, and that antigen processing is altered during disease induction, no existing theory integrates all of these factors through a single, coherent mechanism. In an attempt to focus the field on the need to elucidate such an integrative mechanism, I propose one possibility here that, if nothing else, helps to identify the nature of the problems that need to be addressed. My theory is that autoimmune diseases are induced by normal immunological responses to unique pairs of complementary antigens, at least one of which is a molecular mimic of a host target. Each antigen in the complementary pair induces a complementary immune response (T or B cell); although each immune response is idiotypic in origin, the antigenic complementarity results in what appears to be an idiotype-anti-idiotype relationship between the responses. Additionally, because of the antigenic complementarity, each immune response mimics one of antigens, abrogating the distinction between self and non-self. If at least one of the antigens mimics a host antigen, then the resulting immunological civil war spreads to a host tissue. Complementary antigens also alter antigen processing so that antigens that would normally be proteolytically digested are presented by the major histocompatibility complex (MHC) to T and B cell receptors inducing a cross-reactive immune response. The resulting civil war is supported by the innate immune system due to the complementarity of the initiating antigens.. Complementary antigens stimulate synergistic toll-like receptors (TLR) and/or nucleotide-binding oligomerization receptors (NOD) resulting in up-regulation of cytokine production and further stimulation of the adaptive immune response. Because the immune responses (e.g., antibodies) mimic the initiating antigens, this synergistic activation of innate immunity becomes chronic. Additionally, TLR and NOD function are highly sensitive to sex hormones, some becoming up-regulated and some down-regulated in the presence of either testosterone or estrogens. This sensitivity explains how sex modifies susceptibility to autoimmune diseases. Genetic mutations in TLR, NOD and MHC further alter antigen presentation and the degree to which antigens stimulate an immune response explaining how genetics also modifies susceptibility. Finally, sex hormones also alter the host microbiome, which in turn modulates autoimmune disease risk by shaping the immunological nature of self and by mediating susceptibility to microbial infection. Moreover, it appears that the microbiome camouflages itself from the immune system by mimicking the host antigenic repertoire; the mimicry between the antigens of the microbiome and the host results in selective attacks on microbiome constituents concomitant with any autoimmune attack on host tissues. This antigenic complementarity theory thereby integrates all major elements known to affect, or be affected by, autoimmune diseases and provides a set of testable implications.