Search Results (97)

Background: Nipah virus (NiV), a zoonotic paramyxovirus with high case fatality and pandemic potential, remains without a licensed vaccine for humans to date. Although there has been progress in vaccine development, it remains limited, and peptide vaccines have rarely been validated in vivo. Methods: Here, we report the rational antigen selection, synthesis, and preliminary immunogenicity evaluation of NiV fusion glycoprotein (NiV-F)-derived linear peptides as vaccine candidates. Candidate epitopes were identified by in silico, and a total of 18 B- and T-cell epitope-derived peptides were shortlisted for synthesis and antigenicity validation by ELISA. Results: Antigenicity evaluation showed that 9 of the synthesized peptides have A_450nm of over 1 (8 from the F11 group, A_450nm: 1.13–3.6; 1 from the F18 group, A_450nm: 1.51), with the peptide constructs F11-3 (A_450nm: 3.5) and F11-4 (A_450nm: 3.6) showing the highest antigenicity. Interestingly, peptides from F11 with amidation increased antibody binding (F11-4-NH2, A_450nm: 3.05; F11-4-9mer-1-NH2, A_450nm: 0.87). The lead peptide candidates, F11-3 and F11-4, were subsequently used for the immunization experiment, and mouse sera were assessed against their homologous peptide antigens or recombinant NiV-F protein. ELISA result showed detectable antibody reactivity against their homologous antigen for the intramuscular (IM) F11-3 vaccinated group (A_450nm: 0.30 ± 0.35), whereas increased binding was observed for both IM-administered F11-3 (A_450nm: 1.62 ± 0.97) and F11-4 (A_450nm: 2.0 ± 0.77) against NiV-F protein, albeit without statistical significance compared to the negative control (NC, p > 0.05), and were markedly lower compared to mice immunized with NiV-F recombinant protein (PC, p < 0.01), underscoring the need for further optimization procedures. Conclusions: Collectively, these results support an exploratory antigen discovery and prioritization framework for NiV-F-derived peptide candidates and provide a foundation for future studies aimed at optimizing immunogenicity and evaluating protective relevance in appropriate preclinical models. Full article

Background/Objectives: SARS-CoV-2 continues to generate antigenically divergent variants that reduce the breadth of existing vaccine-induced antibody responses. Fc-fusion subunit vaccines offer advantages in stability, antigen display, and Fc-mediated immune engagement. This study aimed to design and evaluate a tetravalent RBD–Fc fusion construct incorporating RBDs from Wuhan-Hu-1 and Omicron BA.4/BA.5 and to determine whether this configuration can induce broad antibody recognition across SARS-CoV-2 variants. The objective was to assess its feasibility, biochemical properties, and initial immunogenicity. Methods: Immune responses to the construct were first assessed using the C-ImmSim simulation platform. The full-length fusion was synthesized, subcloned into pcDNA3.1(+), expressed in HEK293 cells, and purified by Protein G affinity chromatography. Protein integrity was evaluated by reducing SDS–PAGE. BALB/c mice (female, 8 weeks) were immunized with a prime–boost–boost schedule, and sera were analyzed by ELISA, considering binding to Wuhan-Hu-1, Omicron BA.4/BA.5, and a panel of RBD variants. Results: In silico analysis predicted coordinated antigen clearance, class switching, memory B- and CD4⁺ T-cell formation, and transient cytokine induction. The recombinant protein was expressed efficiently, yielding a major ~56 kDa band and a ~23 kDa RBD fragment. Vaccinated mice generated strong IgG responses to Wuhan-Hu-1 and BA.4/BA.5 RBDs and showed broad binding to major variant RBDs. Conclusions: The tetravalent RBD–Fc fusion vaccine was successfully produced and elicited broad antibody binding across SARS-CoV-2 variants, supporting its potential as a versatile protein-based vaccine platform. Full article

Objectives: The construction of subunit vaccines based on antigens that can induce strong cellular immunity is a widely accepted strategy to develop new tuberculosis vaccines. This study screens immunogens with potential for subunit vaccine development from seven candidate antigens and then verifies their vaccine efficacy. Design: C57BL/6 mice were immunized subcutaneously with purified PPE19, PPE50, FadD21, Rv1505c, Rv1506c, Rv2035, and Rv0976c proteins formulated with Freund’s adjuvant to evaluate both the antigen-specific Th1 cellular immune responses and IgG level. After the vaccination of mice with recombined pcDNA3.1 expressing Rv0976c, intravenous or aerosol infection with M. tb were further challenged to assess protective efficacy. Results: Purified PPE19, PPE50, FadD21, and Rv0976c proteins generated strong antigen-specific Th1 cellular immune responses in mice. Compared to Ag85A, Rv0976c also stimulated higher IgG antibody level in mice. In particular, Rv0976c stimulated high and specific IgG antibody levels in serum from TB patients. The vaccination of mice with DNA vaccines expressing Rv0976c, followed by intravenous challenge with Bacillus Calmette–Guerin (BCG) Pasteur or M. tb, resulted in significant levels of protection that are comparable to or better than that afforded by the two leading antigens, Ag85A and PPE18. Conclusions: These results indicated that Rv0976c was a better protective antigen. Future studies to combine Rv0976c with other antigens and evaluate its effectiveness as a booster of BCG or as a therapeutic vaccine are warranted. Full article

In Nigeria, hepatitis B virus (HBV) infection remains a significant public health issue. The emergence of immune escape mutants (IEMs), basal core promoters, and precore (BCP/PC) mutants among asymptomatic individuals has enabled the continuous evolution of the virus in the country. In this study, we used Sanger sequencing of the S gene and the BCP/PC region to investigate the genetic diversity, phylogenetic relationships, and mutational profiles of HBV strains detected in two regions in Nigeria. A total of 178 HBsAg-positive samples confirmed by ELISA underwent viral DNA extraction and PCR amplification of the surface and BCP/PC genes, and 76 and 60 sequences were found to be exploitable for S and BCP/PC genes, respectively, which were used for HBV genotyping and mutational analysis. We detected various mutations in the major hydrophilic loop (target of neutralizing antibodies), including vaccine escape mutants (VEMs) (L127P/R, S140T/L, and G145A), HBV immunoglobulin resistance mutants (T131N, S143T, and W156R), and mutations previously reported in patients with reactivated infections (T115N, G159A/R, and F161Y). We also identified a high proportion of C1741T in 34/42 (81%) along with A1762T or G1764A mutation in 14/42 (33%) and 18/42 (43%) as the dominant variants in the BCP region. The predominant classical PC G1896A and G1899A variants were identified in 26/42 (62%) and 17/42 (40%) participants in this study. Two HBV genotypes were identified (A and E). However, HBV genotype E was the most frequently identified genotype, and is still the dominant strain circulating in Nigeria. We report the circulation of HBV IEMs and the preponderance of BCP and classical PC variants among asymptomatic carriers. Our findings suggest that the spread of these HBV mutant variants among asymptomatic carriers may have an impact on the effectiveness of diagnostic immunoassays and the success of HBsAg-based vaccinations. This highlights the need for robust surveillance. Full article

Herpes simplex virus type 1 (HSV-1) has a global prevalence of 64%. Established antiviral drugs, such as acyclovir (ACV), have been successfully used over the past decades. However, due to growing viral resistance against approved antivirals and the lack of effective vaccines, new concepts are essential to target HSV-1 infections. Here, we present data on the inhibitory effect of the procaine-based substance ProcCluster^® (PC) in reducing HSV-1 replication in vitro. Non-toxic PC concentrations significantly decreased HSV-1 replication in infected cells. Immunofluorescence microscopy revealed an accumulation of viral proteins in early and recycling endosomes, resulting in reduced viral release. The combination of PC with ACV resulted in an enhanced antiviral effect. Based on these results, PC alone, as well as in combination with ACV, appears to be a promising substance with antiviral potential against HSV-1 infections. Full article

Salmonella Heidelberg (SH) is a major serotype of foodborne Salmonella associated with turkeys. Understanding the effect of antibiotic alternatives (AAs) on the cecal microbiome of turkeys challenged with Salmonella could inform the development of microbiome-based strategies on farms. This study examined the effects of multiple AAs, such as probiotics, Lactobacillus and Propionibacterium, and a Salmonella Typhimurium vaccine, on the turkey cecal microbiome exposed to multidrug-resistant (MDR) SH. Microbial DNA was extracted from the cecal contents of 12-week-old commercial turkeys grown in five treatments for shotgun metagenomic sequencing and analysis: NC—Negative Control; PC—Salmonella Control; LAB—Lactobacillus treatment; PF—P. freudenreichii treatment; and VAC—vaccine treatment. Except for the NC, turkeys were challenged with MDR SH (10⁸ CFU/turkey) on the 11th week. Differential abundance tests at the species level found that all AA treatments resulted in an increased abundance of multiple lactic acid-producing bacteria in the cecum compared to PC. In addition, multiple metabolic pathways were differentially abundant in AA treatments compared to PC. This study highlights the importance of AA strategies producing an increased abundance of lactic acid bacteria and critical metabolic pathways, indicating the potential of AAs to improve the gut health of turkeys during the Salmonella challenge. Full article

A killed, whole-cell vaccine was produced to induce immunity in dogs against leptospirosis. The vaccine, containing serovar Copenhageni, was produced and administered to 12 beagle dogs at both 8 and 12 weeks of age. Ten unvaccinated dogs of the same age group served as the control group. A live, virulent inoculum of Leptospira (1.52 × 10⁹–4.40 × 10⁹ leptospires per dog) was used to challenge the dogs at 2 weeks (Study 1) and 14 months (Study 2) post-booster vaccination. At regular intervals, pre- and post-challenge (PC), the microscopic agglutination test (MAT) was performed to measure antibody titers. Leptospiremia and leptospiruria were determined via culture, and the cytokine, biochemical, and pathological profiles of vaccinates and controls were also assessed. A high antibody response was measurable after booster administration. In Study 1 (onset of immunity), acute leptospirosis was observed in five (100%) out of five unvaccinated dogs. In contrast, no acute clinical leptospirosis developed in vaccinated dogs, except in one (20%) dog with mild clinical signs. In Study 2 (duration of immunity), mild clinical signs were observed in two (40%) of the control dogs, while all vaccinated dogs remained clinically normal. The incidence of leptospiruria and leptospiremia PC was lower in the vaccinated dogs compared to the unvaccinated group. Severe thrombocytopenia occurred in 100% (5/5) of the unvaccinated dogs in Study 1 that exhibited acute severe leptospirosis, whereas 80% (4/5) of the unvaccinated dogs in Study 2 showed mild to moderate thrombocytopenia 3 days after challenge. Four out of five unvaccinated dogs (80%) in Study 1 exhibited icteric tissues and hemorrhages in the lungs and mucosal surfaces of the stomach and intestines. A high IL-10 to TNF-α ratio, observed in the control group of both studies, and severe thrombocytopenia observed in the control group of Study 1, indicative of acute leptospiral disease, were detected. The vaccine prevented acute clinical leptospirosis and reduced the renal carrier state in beagle dogs, and further investigation is required using a larger sample size. Full article

Background/Objectives: The COVID-19 vaccine is a significant technological advancement with widespread global use. However, its effect on cancer immunity, particularly with repeated vaccinations, remains unclear. We aimed to investigate the relationship between repeated vaccinations and pancreatic cancer (PC) prognosis. Additionally, we examined serum IgG4 levels, known to be an immune suppressor which increases with repeated vaccinations. Methods: We retrospectively examined the effect of vaccination on survival in 272 PC patients diagnosed at our hospital from January 2018 to November 2023 and analyzed prognostic factors, including IgG4 levels in 96 PC patients. Immunohistochemistry for Foxp3 in the tumor tissue was performed, and the serum IgG4 level was measured. Serum samples from 79 patients with benign and malignant diseases, including PC, were collected between September and November 2023, and the spike-specific IgG4 level was determined using an enzyme-linked immunosorbent assay. Results: The overall survival (OS) of PC patients was shortened in those vaccinated three times or more, and the total serum IgG4 levels increased with the number of vaccinations. Of note, OS was significantly shorter in the high IgG4 group, and Foxp3-positive cells in the tumor tissues were increased. Repeated vaccinations increased the spike-specific IgG4 levels, and a positive correlation was observed between spike-specific IgG4 and the total IgG4. Conclusions: These findings highlight repeated vaccination as a poor prognostic factor in PC patients and suggest that IgG4 is induced by repeated vaccination and may be associated with a poor prognosis in these patients. Full article

Immunization coverage is a key public health indicator reflecting healthcare accessibility and socio-economic conditions. This study employs Principal Component Analysis (PCA) to construct composite development scores and analyze their relationship with immunization coverage for measles and diphtheria-tetanus-pertussis (DTP) vaccines across 195 countries (2000–2021). The analysis comprises a training period (2000–2015) for score development and a test period (2016–2021) for validation. Variables were selected based on correlation with immunization coverage and standardized before PCA extraction. PC1, the principal component explaining the largest variance, was identified as a key indicator of development disparities. Findings reveal that higher PC1 scores (lower socio-economic development) are associated with reduced immunization rates, while lower PC1 scores (higher socio-economic development) correspond to greater coverage, a trend consistent across both periods. Geospatial analysis highlights stark disparities, particularly in sub-Saharan Africa and South Asia, whereas North America, Europe, and East Asia maintain significantly higher coverage. These results provide policy-relevant insights, demonstrating the utility of PCA-derived scores for resource allocation and targeted interventions. Full article

Background/Objectives: Nucleic acid-based anticancer vaccines are becoming a very active field in the fight against cancer. Here, our goal was to generate an oral DNA vaccine targeting the angiogenic peptide, proadrenomedullin N-terminal 20 peptide (PAMP). Methods: An expression plasmid (PcPAMP) was generated by fusing the tetanus toxin epitopes P2 and P30 to the mouse PAMP sequence to counteract self-tolerance, and the empty plasmid was used as a negative control (PcNeg). The plasmids were introduced into Salmonella typhimurium bacteria that were then transformed into bacterial ghosts. C57BL/6J mice were orally immunized with the ghosts five times at 2-week intervals. Then, B16-F10 melanoma cells were injected into the tail vein to generate lung metastases. Furthermore, naïve CD4⁺ T cells were exposed to PAMP, and their secretome was analyzed by proximity extension assays. Results: Significant levels of anti-PAMP immunoglobulins were detected in the blood of PcPAMP-vaccinated mice and their levels of spleen CD8⁺ T cells were significantly higher than in those treated with PcNeg, indicating that self-tolerance was effectively broken. Although the number and size of lung metastases was similar between both experimental groups, there was a significant reduction in intratumoral angiogenesis and in cancer cell proliferation index in the PcPAMP group. Furthermore, these animals showed an intense infiltration of lymphocytes, including regulatory T cells, and M2-like macrophages into the metastases, that was not evident in the PcNeg group. In addition, PAMP induced upregulation of IL1β, IL6, IL7, IL12, IL27, TNFα, and FGF21, and downregulation of IL16 in naïve CD4⁺ T cells. Conclusions: Although the vaccine was not effective in reducing tumor growth, new proliferative and immune functions have been described for PAMP. These new functions include induction of melanoma proliferation and modulation of lymphocyte and macrophage tumor infiltration dynamics. Full article

Background/Objectives: Over the past two centuries, tuberculosis (TB) has been responsible for approximately one billion deaths and continues to represent a significant global health challenge. Despite extensive research efforts, fully effective strategies for the prevention or eradication of TB remain elusive, highlighting the urgent demand for novel vaccines with enhanced safety profiles and efficacy. Lipoproteins, integral surface proteins of mycobacteria, are frequently associated with virulence and display notable immunogenicity, rendering them promising candidates for vaccine development. This study investigates the potential of the mycobacterial lipoprotein, LprO, as a vaccine antigen against TB. Methods: A pcDNA-lprO DNA vaccine was constructed, and its immunogenicity was evaluated using a murine model. Its protective efficacy was further assessed using a Mycobacterium marinum (M. marinum)-infected zebrafish model. Additionally, a recombinant BCG vaccine strain, BCG Japan::pNBV1-lprO, was generated. Its immunogenicity was tested in mice, and its safety was evaluated in SCID mice. Both vaccine candidates were further assessed in regard to their protective efficacy in a murine Mycobacterium tuberculosis (M. tb) infection model. Results: The pcDNA-lprO vaccine increased the M. tb-specific IFN-γ-secreting lymphocytes in murine spleens and prolonged the survival of zebrafish infected with M. marinum. The recombinant BCG Japan::pNBV1-lprO vaccine elicited M. tb-specific Th1-type immune responses in mice compared to the standard BCG Japan strain. Both vaccines effectively reduced the bacterial burden of M. tb in murine lungs, offering superior protection relative to the control groups. Conclusions: These findings establish LprO as a compelling candidate for TB vaccine development, with both LprO-based DNA and recombinant BCG vaccines demonstrating robust protective effects against TB. Full article

Bacterial chondronecrosis with osteomyelitis (BCO) is caused by several bacteria, including Salmonella, Staphylococcus spp., Escherichia coli, Enterococcus spp., and Mycoplasma spp., and BCO is a significant animal health and welfare issue in broiler production, causing 1–2% of bird condemnation at marketing age and resulting in annual losses of tens of millions of dollars. This study evaluated the efficacy of a probiotic program alone and combined with a multivalent electron beam (eBeam)-inactivated vaccine in reducing BCO lameness. The probiotic program included an Enterococcus faecium spray (E. faecium 669, at 2 × 10⁹ CFU/bird) at hatch and a triple-strain Bacillus-based product (B. subtilis 597, B. subtilis 600, and B. amyloliquefaciens 516 at 1 × 10⁹ CFU/bird/day) in drinking water from day 1 to day 56. An aerosol transmission challenge model simulated commercial bacterial exposure. Birds were divided into five groups: a positive control (PC) group (T1) and a negative control (NC) group (T2) receiving no treatment and three treatment groups receiving the probiotic program (T3), the multivalent vaccine (T4), or both the probiotic program and the multivalent vaccine (T5). Data analyzed via ANOVA (p < 0.05) showed T3, T4, and T5 had significantly lower lameness (43.7%, 40.3%, and 40.7%) than T2 (71.0%) and T1 (83.0%). T5 resulted in reductions comparable to T4, indicating no significant synergistic effect. These findings show that probiotics alone or with a vaccine effectively mitigate BCO lameness, enhance broiler welfare, and reduce economic losses. Full article

Background/Objectives: According to the World Health Organization (WHO) and Centers for Disease Control and Prevention (CDC), an estimated 3–6% of people suffer from post-COVID condition or syndrome (PCS). A subset meets the diagnostic criteria for myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). Studies have reported that SARS-CoV-2 proteins or RNA can persist after acute infection in serum or tissues, but their role in PCS is unclear. Methods: Here, SARS-CoV-2 spike protein was analyzed in the serum of 121 PCS patients with predominant fatigue and exertional intolerance, of whom 72 met diagnostic criteria for ME/CFS, 37 post-COVID recovered healthy controls, and 32 pre-pandemic healthy controls. Results: Spike protein was detected in the serum of 11% of recovered controls, 2% of PCS patients, and 14% of ME/CFS patients between 4 and 31 months after SARS-CoV-2 infection, but not in pre-pandemic samples. The occurrence and concentration of spike protein did not correlate with infection or vaccination timepoints. In ME/CFS patients, spike protein presence was not associated with the severity of symptoms or functional disability. In 5 out of 22 patients who under-went immunoglobulin depletion, spike protein levels were reduced or undetectable after treatment, indicating binding to immunoglobulins. Conclusions: In summary, this study identified serum spike protein in a subset of patients but found no association with ME/CFS. Full article

Porcine epidemic diarrhea virus (PEDV) and transmissible gastroenteritis virus (TGEV) are responsible for significant economic losses in the swine industry. The S1 proteins of these viruses serve as key targets for vaccine development. In this study, prokaryotic expression vectors for pCZN1-PEDV S1, pCZN1-TGEV S1, and pCZN1-PEDV S1-TGEV S1 were constructed. The corresponding proteins were expressed, purified, and used to prepare monovalent, bivalent, and mixed (PEDV S1 + TGEV S1) vaccines. Kunming (KM) mice were immunized with subunit vaccines, with PBS as the negative control (NC) and a commercial inactivated vaccine as the positive control (PC). Immune responses, including specific antibody (IgG, IgG1, IgG2a) levels, virus neutralization, and IFN-γ production, were evaluated. All vaccines induced high levels of specific IgG, IgG1, and IgG2a antibodies. At weeks 2 and 8, the PEDV S1 + TGEV S1 vaccine induced significantly higher levels of specific IgG and IgG1 compared to the PC (p < 0.001). The PEDV S1 vaccine also induced significantly higher specific IgG2a levels than the PC at week 4 (p < 0.0001). Virus neutralization assays demonstrated that the subunit vaccines induced neutralizing antibody levels comparable to or exceeding those of the PC. Furthermore, IFN-γ levels were significantly elevated in all vaccinated groups compared to the NC (p < 0.0001), indicating a robust immune response. These results suggest that the subunit vaccines are promising candidates for the safe and effective control of both PEDV and TGEV infections. Full article

Background: Next-generation vaccines against coronavirus disease 2019 (COVID-19) focus on inducing a long-lasting immune response against severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) and its emerging variants. To achieve this, antigens other than spike proteins have been proposed, and different platforms have been evaluated. Nucleic acid-based vaccines are fundamental for this process. Preclinical data have shown that the SARS-CoV-2 nucleocapsid protein induces a protective cellular immune response, and when combined with the spike protein, the resulting humoral and cellular immune responses are effective against some SARS-CoV-2 variants. Methods: We designed a DNA vaccine against the spike and nucleocapsid proteins of SARS-CoV-2 to generate fusion proteins based on the Delta and Omicron B.5 strains. The most immunogenic regions of the spike and nucleocapsid proteins of the Delta and Omicron B strains were selected using bioinformatics. The nucleotide sequences were cloned into pcDNA3.1, and named pcDNA3.1/D-S1, pcDNA3.1/D-S1N, and pcDNA3.1/O-SN. The immunogenicity of the generated fusion proteins was evaluated by analyzing the humoral and cellular responses elicited after the immunization of BALB/c mice. Results: DNA immunization induced antibody production, neutralization activity, and IFN-γ production. The inclusion of the nucleocapsid regions in the plasmid greatly enhanced the immune response. Moreover, cross-reactions with the variants of interest were confirmed. Conclusions: Plasmids-encoding fusion proteins combining the most immunogenic regions of the spike and nucleocapsid proteins present a promising strategy for designing new and effective vaccines against SARS-CoV-2. Full article