Search Results (877)

Streptococcus pyogenes (Group A Streptococcus, StrepA) is a human pathogen responsible for hundreds of millions of infections each year and remains one of the most prevalent bacterial causes of upper respiratory and skin infections worldwide. Despite its global impact, there is no approved vaccine, and the optimal protective immune response is still not fully understood. In particular, the role of Th17 T cells in immunity against StrepA remains to be explored. We have previously shown that Th17 T cells are induced in humans following StrepA infection. In this study, we investigated the role of Th17 T cells during skin and upper airway StrepA infections. To generate StrepA-specific Th17 T cells, we utilized a novel cationic liposomal adjuvant system. We demonstrated that vaccine-induced Th17 T cells are recruited to the skin and upper airways upon StrepA infection. In the airways, Th17 T cells and IgA correlate with protection, whereas Th1 T cells and IgG do not. To further characterize the recruited Th17 T cells, we used an IL-17 fate-reporter mouse model to track Th17 T cells. Our results show that Th17 T cells outnumber bona fide Th1 T cells in both StrepA-infected skin and upper airways. Surprisingly, most Th17 T cells lose expression of IL-17, and do not express TNFα, IFNγ, and IL-2. Initial single-cell sequencing data suggest the existence of multiple Th17 T cell subsets with distinct expression profiles. We discuss the functional relevance of these subsets in the context of a StrepA infection. Full article

The generation of memory CD8⁺ T cells is essential for establishing protective T cell immunity against pathogens and cancers. However, the cellular and molecular mechanisms underlying memory CD8⁺ T cell formation remain incompletely understood. Reliance on specific pathogen-free (SPF) models, characterized by restricted microbial exposure, may limit our understanding of physiologically relevant immune memory development. This study reveals that CD1d-restricted NKT cells regulate central memory T cell (TCM) generation exclusively in a microbe-rich (“dirty”) environment. Under non-SPF housing, CD1d⁺/⁻ and Ja18⁺/⁻ mice exhibited enhanced TCM formation compared to NKT-deficient controls (CD1d⁻/⁻/Ja18⁻/⁻), demonstrating that microbial experience is required for NKT-mediated TCM regulation. Mechanistically, CD1d-restricted NKT cells increased IL-15Rα expression on CD4⁺ T cells in CD1d⁺/⁻ mice, potentiating IL-15 trans-presentation and thereby activating the IL-15/pSTAT5/Eomes axis critical for TCM maintenance. Functional validation through adoptive transfer of CFSE-labeled OT-1 memory cells revealed an NKT cell-dependent survival advantage in CD1d⁺/⁻ hosts. This provides direct evidence that microbiota-experienced niches shape immune memory. Collectively, these findings establish CD1d-restricted NKT cells as physiological regulators of TCM generation and suggest their potential utility as vaccine adjuvants to enhance protective immunity. Full article

Background: Fowl typhoid (FT), a septicemic infection caused by Salmonella Gallinarum (SG), and H9N2 avian influenza are two economically important diseases that significantly affect the global poultry industry. Methods: We exploited the live attenuated Salmonella Gallinarum (SG) mutant JOL3062 (SG: ∆lon ∆pagL ∆asd) as a delivery system for H9N2 antigens to induce an immunoprotective response against both H9N2 and FT. To enhance immune protection against H9N2, a prokaryotic and eukaryotic dual expression plasmid, pJHL270, was employed. The hemagglutinin (HA) consensus sequence from South Korean avian influenza A virus (AIV) was cloned under the Ptrc promoter for prokaryotic expression, and the B cell epitope of neuraminidase (NA) linked with matrix protein 2 (M2e) was placed for eukaryotic expression. In vitro and in vivo expressions of the H9N2 antigens were validated by qRT-PCR and Western blot, respectively. Results: Oral immunization with JOL3121 induced a significant increase in SG and H9N2-specific serum IgY and cloacal swab IgA antibodies, confirming humoral and mucosal immune responses. Furthermore, FACS analysis showed increased CD4+ and CD8+ T cell populations. On day 28 post-immunization, there was a substantial rise in the hemagglutination inhibition titer in the immunized birds, demonstrating neutralization capabilities of immunization. Both IFN-γ and IL-4 demonstrated a significant increase, indicating a balance of Th1 and Th2 responses. Intranasal challenge with the H9N2 Y280 strain resulted in minimal to no clinical signs with significantly lower lung viral titer in the JOL3121 group. Upon SG wildtype challenge, the immunized birds in the JOL3121 group yielded 20% mortality, while 80% mortality was recorded in the PBS control group. Additionally, bacterial load in the spleen and liver was significantly lower in the immunized birds. Conclusions: The current vaccine model, designed with a host-specific pathogen, SG, delivers a robust immune boost that could enhance dual protection against FT and H9N2 infection, both being significant diseases in poultry, as well as ensure public health. Full article

Background: Chitosan, a family of polysaccharides composed of glucosamine and N-acetyl glucosamine, is a promising adjuvant candidate for eliciting potent immune response. Methods: This study compared the adjuvant effects of chitosan to those of empty lipid nanoparticles (eLNPs) and aluminum hydroxide (alum) following administration of recombinant SARS-CoV-2 spike immunogen in adult mice. Mice received the adjuvanted recombinant protein vaccine in a prime-boost regimen with four weeks interval. Subsequent analyses included serological assessment of antibody responses, evaluation of T cell activity, immune cell recruitment and cytokine profiles at injection site. Results: Compared to alum, chitosan induced a more balanced Th1/Th2 response, akin to that observed with eLNPs, demonstrating its ability to modulate both the humoral and cellular immune pathways. Chitosan induced a different proinflammatory cytokine (e.g., IL-1⍺, IL-2, IL-6, and IL-7) and chemokine (e.g., Eotaxin, IP-10, MIP-1a) profile compared to eLNPs and alum at the injection site and in the draining lymph nodes. Moreover, chitosan potentiated the recruitment of innate immune cells, with neutrophils accounting for about 40% of the infiltrating cells in the muscle, representing a ~10-fold increase compared to alum and a comparable level to eLNPs. Conclusions: These findings collectively indicate that chitosan has the potential to serve as an effective adjuvant, offering comparable, and potentially superior, properties to those of currently approved adjuvants. Full article

Background: Toxoplasma gondii (T. gondii) causes severe disease in immunocompromised individuals and pregnant women, underscoring the urgent need for effective vaccines against toxoplasmosis. The dense granule protein 5 (GRA5) of T. gondii plays a key role in parasitic cyst formation. Methods: This study evaluated the protective immune responses induced by a virus-like particle (VLP) vaccine expressing the T. gondii-derived antigen GRA5 in a mouse model challenged with the ME49 strain of T. gondii. GRA5 VLPs were generated using a baculovirus expression system, and VLP formation was confirmed by Western blotting and visualized using transmission electron microscopy. Mice were intranasally immunized with GRA5 VLPs three times at 4-week intervals to induce immune responses, followed by infection with T. gondii ME49. Results: Intranasal immunization with GRA5 VLPs induced parasite-specific IgG antibody responses in the serum and both IgG and IgA antibody responses in the brain. Compared to the non-immunized group, immunized mice exhibited significantly higher levels of germinal center B cells and antibody-secreting cell responses. Moreover, the VLP vaccine suppressed the production of IFN-γ and IL-6 cytokines, leading to a significant reduction in brain inflammation and decreased cyst counts following lethal challenge with T. gondii ME49 infection. Conclusion: These findings suggest that the GRA5 VLP vaccine derived from T. gondii elicits a protective immune response, highlighting its potential as an effective vaccine candidate against toxoplasmosis. Full article

Background: Chronic cytomegalovirus (CMV) infection may favor the development of immunosenescence and inflammation that impair vaccine responses, including COVID-19. In addition, the polymorphism of the interferon-lambda gene (IFNλ) affects COVID-19 immune responses in older adults. Objective: We aimed to investigate the impact of IFNλ polymorphism (IL28B gene-rs12979860) on the immune/inflammatory response to vaccination with CoronaVac for COVID-19 in older adults who were CMV-seropositive. Methods: Blood samples from 42 CMV-seropositive older adults (73.7 ± 4.5 years) were collected before and 30 days after immunization with a second dose of the CoronaVac vaccine to evaluate the immune/inflammatory response. Results: At genotyping, 20 subjects were homozygous for the C/C alleles (Allele-1 group), 5 were homozygous for the T/T Alleles (Allele-2 group), and 17 were heterozygous (C/T, Alleles-1/2 group). The Allele-1 group showed higher IgG levels for COVID-19 (p = 0.0269) and intermediate monocyte percentage (p = 0.017), in contrast to a lower non-classical monocyte percentage (p = 0.0141) post-vaccination than pre-vaccination. Also, this group showed that IgG levels for CMV were positively associated with a systemic pro-inflammatory state and senescent T cells (CD4+ and CD8+). The Allele-2 group presented higher IFN-β levels at pre- (p = 0.0248) and post-vaccination (p = 0.0206) than the values in the Allele-1 and Alleles-1/2 groups, respectively. In addition, the Allele-2 and Alleles-1/2 groups showed that IgG levels for COVID-19 were positively associated with a balanced systemic inflammatory state. Conclusion: CMV-seropositivity in older adults who had Allele-1 could lead to an unbalanced systemic inflammatory state, which may impair their antibody response to COVID-19 vaccination compared to other volunteer groups. Full article

Background: Canine parvovirus (CPV) is a highly pathogenic virus that predominantly affects puppies, with mortality rates exceeding 70%. Although commercial multivalent live attenuated vaccines (MLV) are widely employed, their efficacy is often compromised by maternal antibody interference. Consequently, the development of novel vaccines remains imperative for effective CPV control. Methods: Recombinant CPV VP2 protein (rVP2) and canine interlukine 12 protein (rcIL-12) were expressed using the Bac-to-Bac baculovirus expression system and the biological activity of these proteins was assessed through hemagglutination, Cell Counting Kit-8 (CCK8) and IFN-γ induction assays. The combined immunoenhancement effect of rVP2 and rcIL-12 protein was evaluated in puppies. Results: Both rVP2 and rcIL-12 were successfully expressed and purified, exhibiting confirmed antigenicity, immunogenicity, and bioactivity. Co-administration of rVP2 with rcIL-12 elicited higher neutralizing antibody titer (6–7 times higher), complete challenge protection efficiency (no clinical symptoms and tissue and organ lesions), fewer viral shedding (decreasing significantly 8-day post challenge) and superior viral blockade (lower viral load in the organism) compared to rVP2 alone. Conclusions: Our findings demonstrate that rVP2 co-administered with rcIL-12 induces robust protective immunity in puppies and significantly mitigated the inhibitory effects of maternal antibodies. This represents a promising strategy for enabling earlier vaccination in puppies and rational design of CPV subunit vaccines. Full article

To genetically characterise an epidemic isolate of feline panleukopenia virus (FPLV) harbouring the Ala91Ser mutation in China, a clinical strain (accession number: OR921195.1), named FPLV-CC19-02, was isolated from a PCR-positive faecal swab sample. Phylogenetic analysis revealed that it is far removed from all current commercial vaccine strains and differs from the FPLV prototype strain Cu-4 (M38246.1), specifically the vaccine strain of Fel-O-Vax^® PCT, at positions 91 (Ala91Ser) and 101 (Ile101Thr) within the VP2 protein. This virus can induce the typical cytopathic effect seen in parvovirus infection in feline kidney cells, resulting in severe clinical symptoms in cats, including haematochezia and hyperthermia. Furthermore, infected cats died of virus infection within 5–10 days post-infection (dpi) (100% morbidity and 83% mortality), indicating that FPLV-CC19-02 is a strain with increased virulence. Additionally, it demonstrated good immunogenicity in cats. Overall, these findings may help us to better understand the molecular prevalence of feline panleukopenia virus in cats and provide valuable basic data for the development of effective, locally adapted feline panleukopenia virus vaccines in China. Full article

SLE is characterized by the generation of a variety of autoantibodies including anti-dsDNA autoantibodies, causing damage in various organs. If autoimmunity is defined by the generation of a variety of autoantibodies against the self, SLE is the only disease to qualify. Identification of the SLE-causing factor must fulfill the following criteria: (i) the factor induces SLE, (ii) the factor is operating in active SLE and (iii) SLE heals after removal of the factor. All candidate factors are reviewed from this viewpoint in this review. As to the cause of SLE, high levels of interferon α can induce SLE; however, interferon α in most patients did not reach this high level. BAFF (B cell activating factor of the TNF family) is increased in SLE. BAFF itself induced some manifestation of SLE, whereas removal of interferon α or BAFF by an antibody (Ab) did not heal SLE. BXSB male mice with a duplicated TLR7 gene develop SLE; however, the gene Sle1 is also required for the development of SLE. In addition, sanroque mice develop a variety of autoantibodies and SLE; the sanroque mutation, which disrupts one of the repressors of ICOS, results in increased CCR7^lo CXCR5⁺Tfh cells, IL-21 and SLE. ICOS⁺T follicular helper (Tfh) cells increase in SLE and SLE-model (NZBxNZW)F1 mice, and the blockade of Tfh development ameliorated SLE, indicating the importance of Tfh cells in the pathogenesis of SLE. Self-organized criticality theory shows that SLE is caused by repeated infection, wherein SLE-inducing pathogens can vary individually depending on one’s HLA; however, the pathogen presented on HLA stimulates the T cell receptor (TCR) strongly beyond self-organized criticality. This stimulation generates TCR-revised, autoreactive DOCK8⁺Tfh cells, which induced a variety of autoantibodies and SLE. The SARS-CoV-2 virus is an example pathogen because SLE occurs after SARS-CoV-2 infection and vaccination. DOCK8⁺Tfh cells and SLE decreased after conventional or anti-DOCK Ab therapies. Thus, DOCK8⁺Tfh cells newly generated after repeated infection fulfill the criteria (i), (ii) and (iii) as the cause of SLE. Full article

Toxoplasma gondii, a parasitic protozoan, causes zoonotic infections with severe health impacts in humans and warm-blooded animals, underscoring the urgent need for effective vaccines to control these infections. In this study, a DNA vaccine encoding TgROP5, TgROP18, TgGRA7, TgGRA15, and TgMIC6 was formulated using the eukaryotic expression vector pVAX I. IL-24 was delivered as a molecular adjuvant using plasmid pVAX-IL-24. BALB/c, C57BL/6, and Kunming mouse strains received the DNA immunization, after which antibody levels, cytokine production, and lymphocyte surface markers were analyzed to assess immune responses. Additionally, survival rates and brain cyst counts were measured 1 to 2 months post-vaccination in experimental models of toxoplasmosis. As a result, compared to controls, the DNA vaccine cocktail significantly increased serum IgG levels, Th1 cytokine production, and proportions of CD4+/CD8+ T cells, leading to extended survival and reduced brain cyst counts post-challenge with T. gondii ME49. Furthermore, the five-gene DNA vaccine cocktail conferred greater protection compared to single-gene immunizations. Co-administration of IL-24 significantly enhanced the immune efficacy of the multi-gene DNA vaccination. Our findings suggest that IL-24 is an effective molecular adjuvant, enhancing the protective immunity of DNA vaccines against T. gondii, supporting its potential role in vaccine strategies targeting other apicomplexan parasites. Full article

The Bacillus Calmette-Guérin (BCG) vaccine confers broad, non-specific immunity that may bolster defenses against respiratory viruses. While NOD2 (nucleotide-binding oligomerization domain-containing protein 2)-driven pathways are central to innate immune responses, the contribution of surface receptor modulation on monocytes to shaping these responses remains underexplored. We analyzed whole-blood cultures from BCG-vaccinated Polish children, stratified by serostatus to SARS-CoV-2 and RSV, and stimulated for 48 h with live BCG, purified viral antigens, or both. RT-qPCR quantified mRNA levels of NOD2 and key cytokines (IL-1β, IL-2, IL-4, IL-6, IL-8, IL-10, TNF), while flow cytometry assessed CD14, HLA-DR, CD11b, and CD206 expression. Co-stimulation with BCG + RSV elicited the strongest transcriptional response, notably a 2–4-fold upregulation of NOD2, IL-1β, and IL-6 versus RSV alone. In SARS-CoV-2(+) donors, RSV alone induced higher NOD2 expression than BCG or BCG + RSV, while IL-2 peaked following BCG + SARS-CoV-2. Across conditions, NOD2 positively correlated with IL-4 and IL-6 but negatively correlated with IL-1β in SARS-CoV-2 cultures. Viral antigens increased CD14 and HLA-DR on monocytes, suggesting activation; CD206 rose only in dual-seropositive children. Our findings indicate that BCG stimulation affects pediatric antiviral immunity through NOD2-related cytokine production and induction of a CD14⁺HLA-DR⁺ phenotype, supporting its potential role in boosting innate defenses against respiratory pathogens. Full article

Background/Objectives: Contagious agalactia (CA) is a disease typically caused by Mycoplasma agalactiae, affecting small ruminants worldwide and being endemic in certain countries. CA causes severe economic losses due to mastitis, agalactia, and arthritis. As an alternative to existing immunoprophylactic measures, this study aimed to develop a recombinant subunit vaccine against M. agalactiae and evaluate its specific immune response in goats. Methods: Goats were divided into three groups: group 1 received recombinant proteins (P40 and MAG_1560), group 2 received formalin-inactivated M. agalactiae, and group 3 received Tris-buffered saline (negative control). All solutions were emulsified in Freund’s adjuvant. Animals were monitored for 181 days. IgG antibody production was assessed by ELISA, and peripheral blood mononuclear cells (PBMCs) were analyzed by real-time PCR for the expression of IL-1β, IFN-γ, IL-12, and MHC class II genes. Results: M. agalactiae-specific antibody response was observed for six months in the sera of animals from group 1. Analysis of cytokine gene expression revealed increased IL-1β mRNA levels over time in both experimental groups. In group 1, IFN-γ mRNA levels increased with P40 stimulation and decreased with MAG_1560. IL-12 mRNA expression decreased over time in group 1 with P40 stimulation, whereas group 2 showed increased IL-12 expression for both proteins. MHC-II expression was stimulated in both groups. Conclusions: The recombinant proteins induced antibody production and cytokine expression, demonstrating immunogenic potential and supporting their promise as vaccine candidates capable of eliciting both humoral and cellular immune responses against M. agalactiae. Full article

The feline calicivirus, herpesvirus, and panleukopenia viruses are major infections that cause serious diseases in cats; however, current trivalent vaccines have limitations in immune efficacy and their duration of protection. This study assesses the immune-enhancing effects of novel adjuvants (feline IL-15, IL-23, and metabolic modulators) on vaccine responses. Forty mice were randomly assigned to four groups: Group A (composite adjuvants), Group B (metabolic regulatory molecules and Mn adjuvant), Group C1 (Mn adjuvant), and Group C2 (a blank commercial vaccine). The results showed that Group A had significantly higher neutralizing antibody titers against calicivirus post-booster immunization, while both Groups A and B exhibited enhanced antibody responses against the herpesvirus and panleukopenia viruses. Notably, Group A displayed increased proportions of memory T cells, follicular B cells, and activated B cells. These findings suggest that the combination of feline IL-15, IL-23, and metabolic modulators are safe and effective immunoadjuvants for trivalent feline vaccines to promote immune cell differentiation and antibody production, thus representing a promising strategy to optimize vaccine efficacy. Full article

Background and aim: The COVID-19 pandemic, caused by SARS-CoV-2, remains a global health crisis despite vaccination efforts, necessitating novel therapeutic strategies. Natural compounds from Syzygium aromaticum (clove), such as eugenol and β-caryophyllene, exhibit antiviral and anti-inflammatory properties, while host genetic factors, including miR-21 rs1292037 polymorphism, may influence disease susceptibility and severity. This study investigates the dual approach of targeting SARS-CoV-2 via Syzygium aromaticum phytoconstituents while assessing the role of miR-21 rs1292037 in COVID-19 pathogenesis. Methods: Firstly, molecular docking and molecular dynamics simulations were employed to assess the binding affinities of eugenol and caryophyllene against seven key SARS-CoV-2 proteins—including Spike-RBD, 3CLpro, and RdRp—using SwissDock (AutoDock Vina) and the Desmond software package, respectively. Secondly, GC-MS was used to characterize the composition of clove extract. Thirdly, pharmacokinetic profiles were predicted using in silico models. Finally, miR-21 rs1292037 genotyping was performed in 100 COVID-19 patients and 100 controls, with cytokine and coagulation markers analyzed. Results: Docking revealed strong binding of eugenol to viral Envelope Protein (−5.267 kcal/mol) and caryophyllene to RdRp (−6.200 kcal/mol). ADMET profiling indicated favorable absorption and low toxicity. Molecular dynamics simulations confirmed stable binding of methyl eugenol and caryophyllene to SARS-CoV-2 proteins, with caryophyllene–7Z4S showing the highest structural stability, highlighting its strong antiviral potential. Genotyping identified the TC genotype as prevalent in patients (52%), correlating with elevated IL-6 and D-dimer levels (p ≤ 0.01), suggesting a hyperinflammatory phenotype. Males exhibited higher ferritin and D-dimer (p < 0.0001), underscoring sex-based disparities. Conclusion: The bioactive constituents of Syzygium aromaticum exhibit strong potential as multi-target antivirals, with molecular simulations highlighting caryophyllene’s particularly stable interaction with the 7Z4S protein. Methyl eugenol also maintained consistent binding across several SARS-CoV-2 targets. Additionally, the miR-21 rs1292037 polymorphism may influence COVID-19 severity through its role in inflammatory regulation. Together, these results support the combined application of phytochemicals and genetic insights in antiviral research, pending further clinical verification. Full article

Virus-like nanoparticles (VNPs) based on Moloney murine leukemia virus represent a well-established platform for the expression of heterologous molecules such as cytokines, cytokine receptors, peptide MHC (pMHC) and major allergens, but their application for inducing protective anti-viral immunity has remained understudied as of yet. Here, we variably fused the wildtype SARS-CoV-2 spike, its receptor-binding domain (RBD) and nucleocapsid (NC) to the minimal CD16b-GPI anchor acceptor sequence for expression on the surface of VNP. Moreover, a CD16b-GPI-anchored single-chain version of IL-12 was tested for its adjuvanticity. VNPs expressing RBD::CD16b-GPI alone or in combination with IL-12::CD16b-GPI were used to immunize BALB/c mice intramuscularly and subsequently to investigate virus-specific humoral and cellular immune responses. CD16b-GPI-anchored viral molecules and IL-12-GPI were well-expressed on HEK-293T-producer cells and purified VNPs. After the immunization of mice with VNPs, RBD-specific antibodies were only induced with RBD-expressing VNPs, but not with empty control VNPs or VNPs solely expressing IL-12. Mice immunized with RBD VNPs produced RBD-specific IgM, IgG_2a and IgG₁ after the first immunization, whereas RBD-specific IgA only appeared after a booster immunization. Protein/peptide microarray and ELISA analyses confirmed exclusive IgG reactivity with folded but not unfolded RBD and showed no specific IgG reactivity with linear RBD peptides. Notably, booster injections gradually increased long-term IgG antibody avidity as measured by ELISA. Interestingly, the final immunization with RBD–Omicron VNPs mainly enhanced preexisting RBD Wuhan Hu-1-specific antibodies. Furthermore, the induced antibodies significantly neutralized SARS-CoV-2 and specifically enhanced cellular cytotoxicity (ADCC) against RBD protein-expressing target cells. In summary, VNPs expressing viral proteins, even in the absence of adjuvants, efficiently induce functional SARS-CoV-2-specific antibodies of all three major classes, making this technology very interesting for future vaccine development and boosting strategies with low reactogenicity. Full article