Potential Vaccine Candidates Research Articles

Bacterial efflux pump OMPs as vaccine candidates against Multidrug-Resistant Gram-negative bacteria.

The emergence and propagation of bacteria resistant to antimicrobial drugs is a serious public health threat worldwide. The current antibacterial arsenal is becoming obsolete and the pace of drug development is decreasing, highlighting the importance of investment in alternative approaches to treat or prevent infections caused by antimicrobial-resistant bacteria. A significant mechanism of antimicrobial resistance employed by Gram-negative bacteria is the overexpression of efflux pumps that can extrude several compounds from the bacteria, including antimicrobials. The overexpression of efflux pump proteins has been detected in several multidrug resistant (MDR) Gram-negative bacteria, drawing attention to these proteins as potential targets against these pathogens. This review will focus on the role of outer membrane proteins (OMPs) from efflux pumps as potential vaccine candidates against clinically relevant MDR Gram-negative bacteria, discussing advantages and pitfalls. Additionally, we will explore the relevance of efflux pump OMP diversity and the possible impact of vaccination on microbiota.

Immunogenic profiling of Mycobacterium tuberculosis Rv1513 reveals its ability to switch on Th1 based immunity.

Tuberculosis (TB) is one of the infectious diseases caused by the pathogen Mycobacterium tuberculosis that continuously threatens the global human health. Bacillus Calmette-Guérin (BCG) vaccine is the only vaccine that has been used clinically to prevent tuberculosis in recent centuries, but its limitations in preventing latent infection and reactivation of tuberculosis do not provide full protection. In this study, we selected the membrane-associated antigen Rv1513 of Mycobacterium. In order to achieve stable expression and function of the target gene, the prokaryotic expression recombinant vector pET30b-Rv1513 was constructed and expressed and purified its protein. Detection of IFN- γ levels in the peripheral blood of TB patients stimulated by whole blood interferon release assay (WBIA) and multi-microsphere flow immunofluorescence luminescence (MFCIA) revealed that the induced production of cytokines, such as IFN-γ and IL-6, was significantly higher than that in the healthy group. Rv1513 combined with adjuvant DMT (adjuvant system liposomes containing dimethyldioctadecylammonium bromide (DDA), monophospholipid A (MPL), and trehalose-660-dibenzoic acid (TDB)) was used to detect serum specific antibodies, cytokine secretion from splenic suprasplenic cell supernatants, and multifunctional T-cell levels in splenocytes in immunised mice. The levels of IFN-γ, TNF-α, and IL-2 secreted by mouse splenocytes were found in the Rv1513+DMT group and the BCG+Rv1513+DMT group. The serum levels of IgG and its subclasses and the number of IFN-γ+T cells, TNF-α+T and IFN-γ+TNF-α+T cells in the induced CD4+/CD8+T cells in mice were significantly higher than those in the BCG group, and the highest levels were found in the BCG+Rv1513+DMT group. These findings suggest that Rv1513/DMT may serve as a potential subunit vaccine candidate that may be effective as a booster vaccine after the first BCG vaccination.

Designing multi-epitope vaccine against human cytomegalovirus integrating pan-genome and reverse vaccinology pipelines

Human cytomegalovirus (HCMV) is accountable for high morbidity in neonates and immunosuppressed individuals. Due to the high genetic variability of HCMV, current prophylactic measures are insufficient. In this study, we employed a pan-genome and reverse vaccinology approach to screen the target for efficient vaccine candidates. Four proteins, envelope glycoprotein M, UL41A, US23, and US28, were shortlisted based on cellular localization, high solubility, antigenicity, and immunogenicity. A total of 29 B-cell and 44 T-cell highly immunogenic and antigenic epitopes with high global population coverage were finalized using immunoinformatics tools and algorithms. Further, the epitopes that were overlapping among the finalized B-cell and T-cell epitopes were linked with suitable linkers to form various combinations of multi-epitopic vaccine constructs. Among 16 vaccine constructs, Vc12 was selected based on physicochemical and structural properties. The docking and molecular simulations of VC12 were performed, which showed its high binding affinity (−23.35 kcal/mol) towards TLR4 due to intermolecular hydrogen bonds, salt bridges, and hydrophobic interactions, and there were only minimal fluctuations. Furthermore, Vc12 eliciting a good response was checked for its expression in Escherichia coli through in silico cloning and codon optimization, suggesting it to be a potent vaccine candidate.

Serogroup B Protein Meningococcal Vaccines and the Formation of Immune Protection against Gonorrhea

Relevance. Gonorrhea is a widespread infection. More than 80 million cases of this disease occur annually. The problem is compounded by the growing resistance of gonococcus to antibiotics worldwide. The only way out in this situation may be the immunization of certain groups of the population against this infection. Despite the numerous efforts of specialists, there is currently no registered vaccine against gonorrhea, which is due to the characteristics of the pathogen. However, over the past 30 years, reliable observations have accumulated that vaccines containing N. meningititidis serogroup B outer membrane proteins (OMP), developed for prophylaxis meningococcal infection, can also prevent a significant proportion of gonorrhea cases. Aims. To give a brief overview of publications on the reduction of the incidence of gonorrhea in individuals who received vaccines containing N. meningitidis serogroup B outer membrane vesicles, followed by an analysis of information about the nature of these proteins and methods of their study, as a promising platform for creating a vaccine against gonococcus. Conclusions. There is a theoretical and real possibility of creating a preventive drug against gonorrhea. Our analysis of literature sources showed that during the period 2006–2016 from 31% to 59% of those vaccinated with the protein meningococcal vaccine В were protected from gonorrhea. It is necessary to continue studying meningococcal OMV in terms of their preventive properties against gonorrhea, improve the set of models to identify their protective effect, and find adjuvants that enhance the immunogenicity of potential vaccine candidates.

Evaluation of vaccine candidates against Rhodococcus equi in BALB/c mice infection model: cellular and humoral immune responses

Rhodococcus equi (R. equi) is a zoonotic opportunistic pathogen that mainly causes fatal lung and extrapulmonary abscesses in foals and immunocompromised individuals. To date, no commercial vaccine against R. equi exists. We previously screened all potential vaccine candidates from the complete genome of R. equi using a reverse vaccinology approach. Five of these candidates, namely ABC transporter substrate-binding protein (ABC transporter), penicillin-binding protein 2 (PBD2), NlpC/P60 family protein (NlpC/P60), esterase family protein (Esterase), and M23 family metallopeptidase (M23) were selected for the evaluation of immunogenicity and immunoprotective effects in BALB/c mice model challenged with R. equi. The results showed that all five vaccine candidate-immunized mice experienced a significant increase in spleen antigen-specific IFN-γ- and TNF-α-positive CD4 + and CD8 + T lymphocytes and generated robust Th1- and Th2-type immune responses and antibody responses. Two weeks after the R. equi challenge, immunization with the five vaccine candidates reduced the bacterial load in the lungs and improved the pathological damage to the lungs and livers compared with those in the control group. NlpC/P60, Esterase, and M23 were more effective than the ABC transporter and PBD2 in inducing protective immunity against R. equi challenge in mice. In addition, these vaccine candidates have the potential to induce T lymphocyte memory immune responses in mice. In summary, these antigens are effective candidates for the development of protective vaccines against R. equi. The R. equi antigen library has been expanded and provides new ideas for the development of multivalent vaccines.

Surface display of the COE antigen of porcine epidemic diarrhoea virus on Bacillus subtilis spores.

Porcine epidemic diarrhoea virus (PEDV) infects pigs of all ages by invading small intestine, causing acute diarrhoea, vomiting, and dehydration with high morbidity and mortality among newborn piglets. However, current PEDV vaccines are not effective to protect the pigs from field epidemic strains because of poor mucosal immune response and strain variation. Therefore, it is indispensable to develop a novel oral vaccine based on epidemic strains. Bacillus subtilis spores are attractive delivery vehicles for oral vaccination on account of the safety, high stability, and low cost. In this study, a chimeric gene CotC-Linker-COE (CLE), comprising of the B. subtilis spore coat gene cotC fused to the core neutralizing epitope CO-26 K equivalent (COE) of the epidemic strain PEDV-AJ1102 spike protein gene, was constructed. Then recombinant B. subtilis displaying the CLE on the spore surface was developed by homologous recombination. Mice were immunized by oral route with B. subtilis 168-CLE, B. subtilis 168, or phosphate-buffered saline (PBS) as control. Results showed that the IgG antibodies and cytokine (IL-4, IFN-γ) levels in the B. subtilis 168-CLE group were significantly higher than the control groups. This study demonstrates that B. subtilis 168-CLE can generate specific systemic immune and mucosal immune responses and is a potential vaccine candidate against PEDV infection.

Insights into structural vaccinology harnessed for universal coronavirus vaccine development.

Structural vaccinology is pivotal in expediting vaccine design through high-throughput screening of immunogenic antigens. Leveraging the structural and functional characteristics of antigens and immune cell receptors, this approach employs protein structural comparison to identify conserved patterns in key pathogenic components. Molecular modeling techniques, including homology modeling and molecular docking, analyze specific three-dimensional (3D) structures and protein interactions and offer valuable insights into the 3D interactions and binding affinity between vaccine candidates and target proteins. In this review, we delve into the utilization of various immunoinformatics and molecular modeling tools to streamline the development of broad-protective vaccines against coronavirus disease 2019 variants. Structural vaccinology significantly enhances our understanding of molecular interactions between hosts and pathogens. By accelerating the pace of developing effective and targeted vaccines, particularly against the rapidly mutating severe acute respiratory syndrome coronavirus 2 and other prevalent infectious diseases, this approach stands at the forefront of advancing immunization strategies. The combination of computational techniques and structural insights not only facilitates the identification of potential vaccine candidates but also contributes to the rational design of vaccines, fostering a more efficient and targeted approach to combatting infectious diseases.

Screening of the dominant immunogenic epitopes of tilapia lake virus

Tilapia lake virus (TiLV) is an emerged contagious pathogen resulting in high mortality and significant socio-economic impacts. Vaccination is the most effective way to protect fish against viral infections, and confirmation of immunogenic epitopes of virus is a prerequisite for designing vaccines. However, the immunogenic epitope of TiLV is unclear. In the study, the immunogenicity of all proteins encoded by TiLV genomic segments was evaluated to screen the dominant immunogenic epitope. All proteins (S1, S2, S3, S4, S527–172, S5196–272, S630–317, S7, S8, S9 and S10) encoded by TiLV genomic segments were obtained by gene cloning, vector construction, expression and purification. Healthy tilapia were vaccinated with these purified proteins, and the immunoprotective effects were evaluated. Results showed that the numbers of erythrocytes, leucocytes, lymphocytes and neutrophils increased significantly in S630–317, S8 and S10 vaccinated groups. The enzyme activities of T-AOC, SOD, ACP and AKP also showed higher levels in S630–317, S8 and S10 vaccinated groups. Additionally, the expression levels of immune-related genes (CC2, TNF-γ, IL-1β, CD4, MyD88 and IFN-γ) also significantly upregulated in S630–317, S8 and S10 vaccinated groups. The relative percentage survival (RPS) of tilapia vaccinated with S630–317, S8 and S10 reached 64.28%, 68.75% and 53.57% at 14 days post TiLV-infection, while the control groups had a 96% mortality rate. These results indicated that S630–317, S8 and S10 can induce strong immune responses. S8 is the dominant immunogenic epitope of TiLV, which can be the potential vaccine candidate for TiLV prevention and control.

Immunoinformatics and Reverse Vaccinology Approach for the Identification of Potential Vaccine Candidates against Vandammella animalimors.

Vandammella animalimorsus is a Gram-negative and non-motile bacterium typically transmitted to humans through direct contact with the saliva of infected animals, primarily through biting, scratches, or licks on fractured skin. The absence of a confirmed post-exposure treatment of V. animalimorsus bacterium highlights the imperative for developing an effective vaccine. We intended to determine potential vaccine candidates and paradigm a chimeric vaccine against V. animalimorsus by accessible public data analysis of the strain by utilizing reverse vaccinology. By subtractive genomics, five outer membranes were prioritized as potential vaccine candidates out of 2590 proteins. Based on the instability index and transmembrane helices, a multidrug transporter protein with locus ID A0A2A2AHJ4 was designated as a potential candidate for vaccine construct. Sixteen immunodominant epitopes were retrieved by utilizing the Immune Epitope Database. The epitope encodes the strong binding affinity, nonallergenic properties, non-toxicity, high antigenicity scores, and high solubility revealing the more appropriate vaccine construct. By utilizing appropriate linkers and adjuvants alongside a suitable adjuvant molecule, the epitopes were integrated into a chimeric vaccine to enhance immunogenicity, successfully eliciting both adaptive and innate immune responses. Moreover, the promising physicochemical features, the binding confirmation of the vaccine to the major innate immune receptor TLR-4, and molecular dynamics simulations of the designed vaccine have revealed the promising potential of the selected candidate. The integration of computational methods and omics data has demonstrated significant advantages in discovering novel vaccine targets and mitigating vaccine failure rates during clinical trials in recent years.

Tailored Viral-like Particles as Drivers of Medical Breakthroughs.

Despite the recognized potential of nanoparticles, only a few formulations have progressed to clinical trials, and an even smaller number have been approved by the regulatory authorities and marketed. Virus-like particles (VLPs) have emerged as promising alternatives to conventional nanoparticles due to their safety, biocompatibility, immunogenicity, structural stability, scalability, and versatility. Furthermore, VLPs can be surface-functionalized with small molecules to improve circulation half-life and target specificity. Through the functionalization and coating of VLPs, it is possible to optimize the response properties to a given stimulus, such as heat, pH, an alternating magnetic field, or even enzymes. Surface functionalization can also modulate other properties, such as biocompatibility, stability, and specificity, deeming VLPs as potential vaccine candidates or delivery systems. This review aims to address the different types of surface functionalization of VLPs, highlighting the more recent cutting-edge technologies that have been explored for the design of tailored VLPs, their importance, and their consequent applicability in the medical field.

Increased of Spleen White Pulp Diameter Post Dbl2β-Pfemp1 Recombinant Protein Injection in Wistar Rats: Pre-Clinical Study for Malaria Vaccine Development

Malaria is a major infectious disease worldwide, and vaccination is essential for disease control. The Plasmodium falciparum Erythrocyte Membrane Protein-1 (PfEMP1) is a potential malaria vaccine candidate due to its involvement in pathogenesis. Injection of DBL2β-PfEMP1 recombinant protein in animal models induces IgG and CD4+ production and inhibits binding with host endothelial receptors. This study aimed to analyze the spleen immune response by measuring the white pulp diameter. The experimental study used Wistar rats (Rattus norvegicus) that were divided into four groups, a control group and three treatment groups, which were injected with 100, 150, and 200 μg of DBL2β-PfEMP1 protein. Injection was done thrice with three-week intervals (days 0, 21, and 42). On day 56, rats were euthanized, and spleens were prepared for histology examination. The white pulp diameter increased along with increasing the dose of protein. The ANOVA test showed a significant difference between groups (p=0.001). The posthoc Bonferroni test showed a significant difference between the control and the 150 and 200 μg groups and the 100 μg and 200 μg groups. In conclusion, the DBL2β-PfEMP1 recombinant protein injection increased the spleen white pulp diameter in Wistar rats, and the 200 μg dose resulted in the highest increase.

Edwardsiella tarda Attenuates Virulence upon Oxytetracycline Resistance.

The relationship between antibiotic resistance and bacterial virulence has not yet been fully explored. Here, we use Edwardsiella tarda as the research model to investigate the proteomic change upon oxytetracycline resistance (LTB4-ROTC). Compared to oxytetracycline-sensitive E. tarda (LTB4-S), LTB4-ROTC has 234 differentially expressed proteins, of which the abundance of 84 proteins is downregulated and 15 proteins are enriched to the Type III secretion system, Type VI secretion system, and flagellum pathways. Functional analysis confirms virulent phenotypes, including autoaggregation, biofilm formation, hemolysis, swimming, and swarming, are impaired in LTB4-ROTC. Furthermore, the in vivo bacterial challenge in both tilapia and zebrafish infection models suggests that the virulence of LTB4-ROTC is attenuated. Analysis of immune gene expression shows that LTB4-ROTC induces a stronger immune response in the spleen but a weaker response in the head kidney than that induced by LTB4-S, suggesting it's a potential vaccine candidate. Zebrafish and tilapia were challenged with a sublethal dose of LTB4-ROTC as a live vaccine followed by LTB4-S challenge. The relative percentage of survival of zebrafish is 60% and that of tilapia is 75% after vaccination. Thus, our study suggests that bacteria that acquire antibiotic resistance may attenuate virulence, which can be explored as a potential live vaccine to tackle bacterial infection in aquaculture.

Selection of vaccine candidates against Pseudomonas koreensis using reverse vaccinology and a preliminary efficacy trial in Empurau (Tor tambroides)

This study marks the first utilization of reverse vaccinology to develop recombinant subunit vaccines against Pseudomonas koreensis infection in Empurau (Tor tambroides). The proteome (5538 proteins) was screened against various filters to prioritize proteins based on features that are associated with virulence, subcellular localization, transmembrane helical structure, antigenicity, essentiality, non-homology with the host proteome, molecular weight, and stability, which led to the identification of eight potential vaccine candidates. These potential vaccine candidates were cloned and expressed, with six achieving successful expression and purification. The antigens were formulated into two distinct vaccine mixtures, Vac A and Vac B, and their protective efficacy was assessed through in vivo challenge experiments. Vac A and Vac B demonstrated high protective efficacies of 100 % and 81.2 %, respectively. Histological analyses revealed reduced tissue damage in vaccinated fish after experimental infection, with Vac A showing no adverse effects, whereas Vac B exhibited mild degenerative changes. Quantitative real-time PCR results showed a significant upregulation of TNF-α and downregulation of IL-1β in the kidneys, spleen, gills, and intestine in both Vac A- and Vac B-immunized fish after challenged with P. koreensis. Additionally, IL-8 exhibits tissue-specific differential expression, with significant upregulation in the kidney, gills, and intestine, and downregulation in the spleen, particularly notable in Vac A-immunized fish. The research underscores the effectiveness of the reverse vaccinology approach in fish and demonstrates the promising potential of Vac A and Vac B as recombinant subunit vaccines.

Immunoinformatic prediction to identify Staphylococcus aureus peptides that bind to CD8+ T-cells as potential vaccine candidates.

Staphylococcus aureus, with its diverse virulence factors and immune response evasion mechanisms, presents a formidable challenge as an opportunistic pathogen. Developing an effective vaccine against S. aureus has proven elusive despite extensive efforts. Autologous Staphylococcus lysate (ASL) treatment has proven effective in triggering an immune response against bovine mastitis. Peptides that stimulate the immune response can be the subject of further research. The study aimed to use immunoinformatics tools to identify epitopes on S. aureus surface and secretory proteins that can bind to major histocompatibility complex class I (MHC I) and CD8+ T-cells. This method aids in discovering prospective vaccine candidates and elucidating the rationale behind ASL therapy's efficacy. Proteins were identified using both literature search and the National Center for Biotechnology Information search engine Entrez. Self and non-self peptides, allergenicity predictions, epitope locations, and physicochemical characteristics were determined using sequence alignment, AllerTOP, SVMTriP, and Protein-Sol tools. Hex was employed for simulating the docking interactions between S. aureus proteins and the MHC I + CD8+ T-cells complex. The binding sites of S. aureus proteins were assessed using Computer Atlas of Surface Topography of Proteins (CASTp) while docked with MHC I and CD8+ T-cells. Nine potential S. aureus peptides and their corresponding epitopes were identified in this study, stimulating cytotoxic T-cell mediated immunity. The peptides were analyzed for similarity with self-antigens and allergenicity. 1d20, 2noj, 1n67, 1nu7, 1amx, and 2b71, non-self and stable, are potential elicitors of the cytotoxic T-cell response. The energy values from docking simulations of peptide-MHC I complexes with the CD8+ and T-cell receptor (TCR) indicate the stability and strength of the formed complexes. These peptides - 2noj, 1d20, 1n67, 2b71, 1nu7, 1yn3, 1amx, 2gi9, and 1edk - demonstrated robust MHC I binding, as evidenced by their low binding energies. Peptide 2gi9 exhibited the lowest energy value, followed by 2noj, 1nu7, 1n67, and 1d20, when docked with MHC I and CD8 + TCR, suggesting a highly stable complex. CASTp analysis indicated substantial binding pockets in the docked complexes, with peptide 1d20 showing the highest values for area and volume, suggesting its potential as an effective elicitor of immunological responses. These peptides - 2noj, 2gi9, 1d20, and 1n67 - stand out for vaccine development and T-cell activation against S. aureus. This study sheds light on the design and development of S. aureus vaccines, highlighting the significance of employing computational methods in conjunction with experimental verification. The significance of T-cell responses in combating S. aureus infections is emphasized by this study. More experiments are needed to confirm the effectiveness of these vaccine candidates and discover their possible medical uses.

The Application of MD Simulation to Lead Identification, Vaccine Design, and Structural Studies in Combat against Leishmaniasis - A Review.

Drug discovery, vaccine design, and protein interaction studies are rapidly moving toward the routine use of molecular dynamics simulations (MDS) and related methods. As a result of MDS, it is possible to gain insights into the dynamics and function of identified drug targets, antibody-antigen interactions, potential vaccine candidates, intrinsically disordered proteins, and essential proteins. The MDS appears to be used in all possible ways in combating diseases such as cancer, however, it has not been well documented as to how effectively it is applied to infectious diseases such as Leishmaniasis. As a result, this review aims to survey the application of MDS in combating leishmaniasis. We have systematically collected articles that illustrate the implementation of MDS in drug discovery, vaccine development, and structural studies related to Leishmaniasis. Of all the articles reviewed, we identified that only a limited number of studies focused on the development of vaccines against Leishmaniasis through MDS. Also, the PCA and FEL studies were not carried out in most of the studies. These two were globally accepted utilities to understand the conformational changes and hence it is recommended that this analysis should be taken up in similar approaches in the future.

Expression of Recombinant OmpA (rOmpA) and In vitro Validation of Antibody Mediated Cross Reactivity among the Enterobacteriaceae Pathogens

Enterobacteriaceae pathogens such as Escherichia coli, Salmonella sp., Shigella sp., Proteus sp., and Klebsiella pneumoniae cause a wide range of gastrointestinal and other mucosal infections. These bacteria acquire antibiotic resistance very quickly and evolve into multi-drug resistant strains thereby making the treatment very difficult. The outer membrane proteins (OMPs) in Enterobacteriaceae are potential vaccine candidates owing for their high immunogenicity and amino acid conservation. The OmpA is one such protein which need to be investigated for the development of a potential subunit vaccine against multiple infections casued by the pathogens of Enterobacteriaceae. To investigate this, we expressed and purified the highly conserved OmpA of S. typhimurium and studied the antibody mediated cross reactivity with the other Enterobacteriaceae pathogens. This was validated through dot ELISA performed with the hyperimmune sera raised against rOmpA of S. typhimurium. We further analyzed the sequence of OmpA protein and clearly understood that the B-cell epitopes in the protein are highly conserved are responsible for cross reactivity among the Enterobacteriaceae pathogens. This work led to findings that provide strong evidence for the application of OmpA in broad-spectrum subunit vaccine against enteric infections.

Inhibition of Plasmodium knowlesi merozoite invasion into human erythrocytes by antibodies raised against the parasite's secreted protein with altered thrombospondin repeat (SPATR).

The Plasmodium secreted protein with an altered thrombospondin repeat (SPATR) has been known to play an important role in the malaria parasite's invasion into host erythrocytes. This protein is immunogenic and has been considered as one of the potential vaccine candidates against malaria parasite infection. Thus far, only a handful immunological studies have been carried out on P. knowlesi SPATR (PkSPATR), and none of these studies investigated the immunoprotective properties of the protein. In the present study, the ability of anti-PkSPATR antibodies to inhibit invasion of human erythrocytes was assessed in an in vitro merozoite invasion inhibition assay. The antibodies were harvested from the serum of a rabbit which was immunised with recombinat PkSPATR. Results from the merozoite invasion inhibition assay revealed significant antibody invasion inhibitory activity in a concentration dependent manner (concentration range: 0.375 - 3.00 mg/ml) with inhibition rate ranging from 20% to 32%. Future studies, such as anti-PkSPATR antibodies inhibitory effect on sporozoite invasion of human liver cells, need to be carried out to assess the potential of PkSPATR as a knowlesi malaria vaccine candidate.

Immune Response to the Recombinant Apa Protein from Mycobacterium tuberculosis Expressed in Streptomyces lividans After Intranasal Administration in Mice. Induction of Protective Response to Tubercle Bacillus Aerosols Exposure

Identifying and evaluating potential vaccine candidates has become one of the main objectives to combat tuberculosis. Among them, mannosylated Apa antigen from Mycobacterium tuberculosis and the non-mannosylated protein expressed in Escherichia coli, have been studied. Although both proteins can induce a protective response in mice, it has been considered that native protein can be dispensed. In this work, we study the protective response induced by Apa expressed in E. coli and in Streptomyces lividans. The latter, like native is secreted as a double band of 45/47 kDa, however, only its 47 kDa band is mannosylated. Both antigens and BCG were intranasal administrated in mice, and animals were then challenged by aerosol with M. tuberculosis H37Rv. The results showed that both, Apa from S. lividans and E. coli conferred statistically significantly protection to animals compared to controls. The cytokine immune response was studied by an immunoassay after animals’ immunization, revealing that Apa from S. lividans induced a statistically significant proliferation of T cell, as well as the expression of IFN-γ, IL-1β, IL-17 and IL-10. In contrast, non-proliferation was obtained with non-mannosylated protein, but induction of IL-12 and IL-17 was observed. Together, these results demonstrate that both proteins were able to modulate a specific immune response against M. tuberculosis, that could be driven by different mechanisms possibly associated with the presence or not of mannosylation. Furthermore, stimulation of cells from BCG-vaccinated animals with the proteins could be an important tool, to help define the use of a given subunit-vaccine after BCG vaccination.

Systems approach to design multi-epitopic peptide vaccine candidate against fowl adenovirus structural proteins for Gallus gallus domesticus.

Fowl adenovirus (FAdV) is a significant pathogen in poultry, causing various diseases such as hepatitis-hydropericardium, inclusion body hepatitis, and gizzard erosion. Different serotypes of FAdV are associated with specific conditions, highlighting the need for targeted prevention strategies. Given the rising prevalence of FAdV-related diseases globally, effective vaccination and biosecurity measures are crucial. In this study, we explore the potential of structural proteins to design a multi-epitope vaccine targeting FAdV. We employed an in silico approach to design the multi-epitope vaccine. Essential viral structural proteins, including hexon, penton, and fiber protein, were selected as vaccine targets. T-cell and B-cell epitopes binding to MHC-I and MHC-II molecules were predicted using computational methods. Molecular docking studies were conducted to validate the interaction of the multi-epitope vaccine candidate with chicken Toll-like receptors 2 and 5. Our in silico methodology successfully identified potential T-cell and B-cell epitopes within the selected viral structural proteins. Molecular docking studies revealed strong interactions between the multi-epitope vaccine candidate and chicken Toll-like receptors 2 and 5, indicating the structural integrity and immunogenic potential of the designed vaccine. The designed multi-epitope vaccine presents a promising approach for combating FAdV infections in chickens. By targeting essential viral structural proteins, the vaccine is expected to induce a robust immunological response. The in silico methodology utilized in this study provides a rapid and cost-effective means of vaccine design, offering insights into potential vaccine candidates before experimental validation. Future studies should focus on in vitro and in vivo evaluations to further assess the efficacy and safety of the proposed vaccine.

Plasmodium vivax HAP2 genetic diversity and population structure from worldwide clinical samples. A potential Transmission-Blocking malaria vaccine candidate

BackgroundMalaria infections due to Plasmodium vivax are increasingly becoming a significant public health problem and are directly impacting malaria elimination efforts in many countries. Recent functional studies have shown that a pre-fertilising antigen; gamete membrane fusion protein HAP2/Generative Cell specific 1 (GCS1) domain significantly reduces the formation of P. vivax oocysts in mosquitos, implying that it could be developed as a transmission-blocking vaccine. MethodsIn this study, the genetic diversity, natural selection, haplotype network analysis and population structure of PvHAP2/GCS1 full-length gene using worldwide samples from 16 countries are determined and the implications for its use as a potential vaccine candidate against P. vivax are discussed. ResultsThe study revealed low levels of nucleotide diversity (π ∼ 0.003, SNPs = 95) and purifying selection for the full-length PvHAP2 gene indicating functional constraints. Among the 95 SNPs (65 synonymous and 30 non-synonymous), 15 non-synonymous substitutions were localised to the C-terminal domain of the protein (674a.a − 862a.a) majority of these non-synonymous substitutions were from two countries of Central Africa i.e. Cameroon and Gabon. Phylogeographic haplotype network analysis indicated that a major haplotype (Hap_2, n = 34) is shared among countries from Asian countries and South American countries. Population structure analysis using a robust Bayesian algorithm indicated the existence of two sub-populations of PvHAP2/GCS1 among the worldwide samples. ConclusionThis study suggests that, due to low genetic diversity across 15 countries, and shared haplotype identified, the HAP2 gene can be a good target for vaccine development as a transmission-blocking vaccine with the potential to provide strain-transcending immunity. The C-terminal region from two countries from Central Africa (Cameroon and Gabon) identified high number of non-synonymous substitutions, which may indicate new adaption of parasites from these countries. However, more detailed field based studies with a larger sample size from these countries are needed.