Vaccination has been one of the most successful and the most significant scientific advances in human health and life expectancy all around the globe. The World Health Organization considers that immunization should be recognized as the main component of human health right, due to the fact that vaccination prevents 2.5 million deaths annually (World Health Organization, 2011). The most successful vaccines have been developed using conventional methods that follow the paradigm established by Pasteur: "to isolate, inactivate and inject" the pathogen microorganism and mimic a natural infection. Recently, metagenomics have played an important role in the discovery of new immunogens for vaccine design and the selection of antigens based on genomic information. The main approach that has used this strategy has been called "reverse vaccinology". This promising and arising field allows the screening of the entire potential antigenic repertoire of an organism using predictive bioinformatic tools. Once the antigenic protein or proteins have been selected, they are expressed and purified using molecular cloning and in vitro expression techniques. Following the in vitro production step, they are probed in animal models to evaluate the in vivo protective strength of the immune response. The main aim of this in vivo approach is to evaluate the ability of the immune response to eliminate or neutralize the pathogen at the time of infection. Those antigens capable of generate a specific immune response with neutralizing activity for natural infections are the best candidate vaccines. In this review we summarize the evolution of vaccinology since its inception, with special emphasis on the development of VLPs as vaccine platforms and their future in preventive medicine and we introduce a new recombinant platform for antigen presentation based on Junin virus VLPs (JUNV-VLPs).

The appearance of the novel betacoronavirus 2019-nCoV represents a major threat to human health, and its diffusion around the world is predicted to have dramatic economic consequences. The knowledge of the 3D structures of 2019-nCoV proteins can facilitate the development of diagnostic and therapeutic molecules. Herein, we apply our energy-based method for the prediction of potential epitopes on viral proteins to design peptide-based molecules that can subsequently be used in diagnostic and therapeutic applications. We discuss these aspects in the paper.The designs have not been tested. Our aim is to share information that can be useful in the development of novel biomolecules with potential interesting activities against 2019-nCoV.

Immunosenescence refers to age-related alterations of the immune system function affecting both the humoral and cellular arm of immunity. Understanding immunosenescence and its impact on vaccination of older adults is essential since primary vaccine responses in older individuals can fail to generate complete protection, especially vaccines targeting infections with increased incidence among the elderly, such as the respiratory syncytial virus. Here, we review the clinical trials of both candidate and approved vaccines against respiratory syncytial virus (RSV), which include adults aged ≥50 years, with an emphasis on the evaluation of immunogenicity parameters. Currently, there are 10 vaccine candidates and 2 vaccines approved for the prevention of RSV in the older adult population. The number of registered clinical trials for this age group amounts to 32. Our preliminary evaluation of published results and interim analyses of the RSV vaccine clinical trials indicates efficacy in older adult participants, demonstrating immunity levels that closely resemble those of younger adult participants.

The SARS–CoV-2 infection has caused both acute and chronic COVID–19 disease during the recent pandemic with emerging more transmissible SARS–CoV–2 Omicron variants (BQ1 and XBB1) that have increased demands for more effective immunogens and therapeutic approaches to protect the lives of numerous SARS–CoV-2 affected individuals and reduce overall disease burden that could be affected by concurrent other pathogens causing diseases. Following a worldwide campaign of mass vaccination, there is still a significant demand to quell the harmful effects of novel SARS–CoV–2 infections due to higher mutation rates within specific areas of the SARS–CoV-2 domain, leading to enhanced viral entry, especially within individuals with one or more significant comorbidities, and there is still a dilemma of how prevention of future pandemics will occur as within host animal mutations and cross species transfer naturally occurs. Concerns intersect at a specific point; a gained evolutionary ability of several viruses over the previous centuries to remain undetected during the first stages of infection by means of capping the 5' end of their DNA and RNA genes respectively. This may occur by reducing the rate of host Type I and Type III Interferons (IFN) cellular synthesis, that would usually occur and affect both apoptotic pathways, that facilitate viral replication and clearance, as well as immune cells, that process and present pathogenic antigen epitopes. Furthermore, although methods of vaccination exist, other methods in clinical development remain that could evoke an immune response in different cellular, serum or mucosal compartments being cellular, serum and mucosal that evoke differential antibody responses. Antibodies are classed as natural and synthetic. Natural antibodies are further classified into neutralizing and non-neutralizing, whilst synthetic antibodies are also further classified into monoclonal and polyclonal. As a result of single cell study transcriptome research, viruses do utilize an array of protein receptors for receptor-mediated cellular entry. This, therefore suggests that potential differential production of antibody immunoglobulins (Ig) within serum and mucosal areas remains affected by cytokines, adhesion molecules and chemokines that can be upregulated or downregulated upon host viral infection. Serum plasma antibodies can be multimeric that may not efficiently cross the nasal epithelium cell layer, therefore offering less protection against mucosal inflammation due to mucin proteins. On the other hand, antibodies produced by mucosal plasma cells at epithelial surfaces are known to provide effective immune responses in some viral infections. The existence of developments that stimulate mucosal immune responses has so far only been seen with influenza nasal immunogens. Nevertheless, scientists developed ways of immunization and early treatment worldwide that generally showed good success rates and fewer risks of adverse events, and the still early present stages of COVID-19 research should also be taken into consideration. For example, the administration of human interferons I and III into the nasal mucosa cellular layer, as key mediators of anti–viral activity, can stimulate cellular activity to train the innate and adaptive immune system cells to develop and appropriately stimulate an adequate immune response through B and T cells. Recently, it was discovered that specific plants secrete proteins that also stimulate the production of Type I Interferons. It might be that focusing on directly offering the immune system the information about the genetics and protein structure of the pathogen, rather than training its first-line mechanisms to develop faster, excessively increases its specificity, making it reach a level that brings the virus the opportunity to evolve and escape previously-developed host immune mechanisms. Naturally-selected polymorphic viruses through genetic recombination pose challenges to traditional concepts of cellular and molecular immune system neutralization of these viruses during the first stages of cellular infection. It is until the scientific community realizes this potentially crucial aspect that we will probably continue to face serious epidemics and pandemics of respiratory diseases over the coming several decades, evidenced with dengue fever and more recently monkeypox. Type I IFNs tend to be produced faster than Type III IFNs, and the first induce slightly more abundant pro-inflammatory signals than the latter, meaning that type III IFNs, if produced early, may further decrease the extent of excessive proinflammatory signals. Hence, we believe that nasal sprays containing a low dosage of Type I and Type III IFNs not only represent a relevant COVID-19 therapeutic, but also a potential unknown modulatory therapy of the future. Of note, it has been indicated that IFN I and / or III display significant immunizing and early therapeutic effects for other viral evoked diseases like Influenza (Influenza (A)H1N1), rabies (Rabies lyssavirus), measles (Measles virus), rubella (Rubivirus rubellae), Hepatitis B, HIV-induced AIDS, Ebola, Marburg, as well as bacterial diseases, such as lower respiratory tract infectious diseases induced by Haemophilus influenzae, Streptococcus pneumoniae and Staphylococcus aureus, and a number of oncological diseases, like hepatic melanoma.

Pseudomonas aeruginosa is a critical healthcare challenge due to its ability to cause persistent infections and the acquisition of antibiotic resistance mechanisms. Lack of preventive vaccines and rampant drug resistance phenomenon has rendered patients vulnerable. As new antimicrobials are in the preclinical stages of development, mining for the unexploited drug targets is also crucial. Here, we designed a chimeric vaccine against P. aeruginosa using a subtractive proteomics approach and identified nine unique enzymes as novel drug targets in PAO1 proteome. A total of five unique proteins were selected as potential vaccine candidates based on essentiality, extracellular localization, virulence, antigenicity, pathway association, protein-protein interaction analysis, hydrophilicity, and low molecular weight. These include two outer membrane porins OprF (P13794) and OprD (P32722), a protein activator precursor pra (G3XDA9), a probable outer membrane protein precursor PA1288 (Q9I456), and a conserved hypothetical protein PA4874 (Q9HUT9). These proteins were further analyzed using a reverse vaccinology approach to identify immunogenic and antigenic T cell and B cell epitopes. The best scoring epitopes qualifying for all set criteria were then further subjected to the construction of a polypeptide multi-epitope vaccine construct with cholera toxin B (CtxB) subunit as an adjuvant. The identified drug targets qualifying the screening criteria were: UDP-2-acetamido-2-deoxy-d-glucuronic acid 3-dehydrogenase WbpB (G3XD23), aspartate semialdehyde dehydrogenase (Q51344), 2-amino-4-hydroxy-6-hydroxymethyldihydropteridine pyrophosphokinase (Q9HV71), 3-deoxy-D-manno-octulosonic-acid transferase (Q9HUH7), glycyl-tRNA synthetase alpha chain (Q9I7B7), riboflavin kinase/FAD synthase (Q9HVM3), aconitate hydratase 2 (Q9I2V5), probable glycosyltransferase WbpH (G3XD85) and UDP-3-O-[3-hydroxylauroyl] glucosamine N-acyltransferase (Q9HXY6). For druggability and pocketome analysis crystal and homology structures of these proteins were retrieved and developed. A sequence-based search was performed in different databases (ChEMBL, Drug Bank, PubChem and Pseudomonas database) for the availability of reported ligands and tested drugs for the screened targets. These predicted targets may provide a basis for the development of reliable antibacterial preventive and therapeutic options against P. aeruginosa.