African swine fever virus (ASFV) is a highly infectious viral pathogen that endangers the global pig industry, and no effective vaccine is available thus far. The CD2v protein is a glycoprotein on the outer envelope of ASFV, which mediates the transmission of the virus in the blood and recognition of the virus serotype, playing an important role in ASFV vaccine development and disease prevention. Here, we generated two specific monoclonal antibodies (mAbs), 6C11 and 8F12 (subtype IgG1/kappa-type), against the ASFV CD2v extracellular domain (CD2v-ex, GenBank: MK128995.1, 1–588 bp) and characterized their specificity. Peptide scanning technology was used to identify the epitopes recognized by mAbs 6C11 and 8F12. As a result, two novel B cell epitopes, ³⁸DINGVSWN⁴⁵ and ¹³⁴GTNTNIY¹⁴⁰, were defined. Amino acid sequence alignment showed that the defined epitopes were conserved in all referenced ASFV strains from various regions of China including the highly pathogenic, epidemic strain, Georgia2007/1 (NC_044959.2), with the same noted substitutions compared to the four foreign ASFV wild-type strains. This study provides important reference values for the design and development of an ASFV vaccine and useful biological materials for the functional study of the CD2v protein by deletion analysis.

• The full identification of ASFV's antigenic epitopes is essential for the creation of targeted serological assays and the development of efficacious subunit vaccines. • The p30 protein is capable of producing neutralizing antibodies. • The monoclonal antibody specifically recognized transiently expressed p30 protein and the inactivated ASFV Pig/HLJ/2018 strain. • The monoclonal antibody against p30 protein recognized a novel linear and immunodominant epitope. • These findings may serve as a basis for the development of serological diagnostic methods and subunit vaccines.

Viruses deploy sophisticated strategies to hijack the host’s translation machinery to favor viral protein synthesis and counteract innate cellular defenses. However, little is known about the mechanisms by which Senecavirus A (SVA) controls the host’s translation. Using a series of sophisticated molecular cell manipulation techniques, heterogeneous nuclear ribonucleoprotein A2B1 (hnRNPA2B1) was identified as an essential host factor involved in translation control in SVA-infected cells. It was also determined that the SVA structural protein, VP3, binds to and relocalizes hnRNPA2B1, which interferes with the host’s protein synthesis machinery to establish a cellular environment that facilitates viral propagation via a two-pronged strategy: first, hnRNPA2B1 serves as a potent internal ribosome entry site (IRES) trans -acting factor, which is selectively co-opted to promote viral IRES-driven translation by supporting the assembly of translation initiation complexes. Second, a strong repression of host cell translation occurs in the context of the VP3-hnRNPA2B1 interaction, resulting in attenuation of the interferons response. This is the first study to demonstrate the interaction between SVA VP3 and hnRNPA2B1, and to characterize their key roles in manipulating translation. This novel dual mechanism, which regulates selective mRNA translation and immune evasion of virus-infected cells, highlights the VP3-hnRNPA2B1 complex as a potential target for the development of modified antiviral or oncolytic reagents. IMPORTANCE: Viral reproduction is contingent on viral protein synthesis, which relies entirely on the host's translation machinery. As such, viruses often need to control the cellular translational apparatus to favor viral protein production and avoid host innate defenses. Senecavirus A (SVA) is an important virus, both as an emerging pathogen in the pork industry and as a potential oncolytic virus for neuroendocrine cancers. Here, heterogeneous nuclear ribonucleoprotein A2B1 (hnRNPA2B1) was identified as a critical regulator of the translational landscape during SVA infection. This study supports a model whereby the VP3 protein of SVA efficiently subverts the host’s protein synthesis machinery through its ability to bind to and relocalize hnRNPA2B1, not only selectively promoting viral internal ribosome entry site-driven translation but also resulting in global translation shutdown and immune evasion. Together, these data provide new insights into how the complex interactions between translation machinery, SVA, and innate immunity contribute to the pathogenicity of the SVA.

Objectives: Infectious bursal disease virus (IBDV) is a highly contagious, acutely infectious agent that causes immunosuppression in chickens. We expressed IBDV VP2 proteins in Escherichia coli (E. coli) to develop an effective virus-like-particles (VLPs) vaccine and evaluated its immunogenicity. Methods: The VLPs produced in E. coli were used as an immunogen mixed with a water-in-mineral-oil adjuvant (Montanide^TM ISA 71 VG, ISA 71 RVG) or a white oil (7#) adjuvant. VLPs without an adjuvant, commercial subunit vaccine, inactivated vaccine, and attenuated vaccine were used as controls. These test vaccines were intramuscularly injected into 19-day-old SPF chickens, which were challenged with the IBDV virulent strain at 30 days after vaccination. Results: The adjuvants boosted antibody production, and the adjuvant groups (except white oil) produced higher antibody levels than the non-adjuvanted controls and the commercial vaccine groups. In terms of cellular immunity, the VLPs plus adjuvant combinations produced higher levels of cytokines, IL-2, IL-4, and IFN-γ than the controls. Conclusion: IBDV VLPs plus the ISA 71 RVG adjuvant can be used as an optimal vaccine combination for improving the immune efficacy of IBD subunit vaccines, which can protect against the virulent strain.

Porcine parvovirus (PPV) is a major pathogen causing reproductive disorders in sows and remains widely prevalent worldwide. In recent years, PPV has undergone rapid mutations and frequently co-infects with other pathogens, making vaccination the most effective preventive measure. Our previous study showed that co-expression of the chaperone protein Tf16 and VP2 in prokaryotic cells could produce highly immunogenic PPV virus-like particles (VLPs). However, whether these VLP vaccines can induce durable immune memory through sustained antibody recall responses has not been fully elucidated. In this study, mice were immunized with VLPs formulated with ISA 201 VG adjuvant, and the responses of follicular helper T cells (Tfh) and germinal center B cells (GC B cells) were analyzed. The results demonstrated that recombinant VLPs significantly enhanced Tfh and GC B cell responses after the third immunization compared to a commercial inactivated vaccine. More importantly, PPV VLPs effectively induced the generation of specific long-lived plasma cells (LLPCs) and memory B cells (MBCs). These findings enhance our understanding of PPV VLP immunogenicity and may inform the design of more efficacious PPV vaccines.

Infectious bursal disease virus (IBDV) remains a major global threat to poultry, causing severe immunosuppression and substantial economic losses. Existing vaccines live-attenuated, inactivated, and subunit provide incomplete protection and face challenges of safety, antigenic mismatch, and repeated dosing requirements. Nano-adjuvant technologies offer a transformative solution, enhancing vaccine immunogenicity, stability, and targeted delivery. Platforms include lipid nanoparticles, polymeric systems, virosomes, mesoporous silica, polysaccharides, and nanoemulsions elicit robust humoral and cellular immune responses, promote Th1/Th2 balance, and enable dose-sparing strategies. Toll-like receptor agonist-loaded nano-adjuvants further amplify dendritic cell activation, antigen presentation, and durable memory responses. Virus-like particles and virosomes structurally mimic IBDV antigens, enhancing immunogenicity without the risks of viral replication. Rational integration of precise antigen selection, multifunctional nano-adjuvants, and advanced delivery approaches promises next-generation vaccines capable of broad, long-lasting protection against very virulent and emerging IBDV variants. These innovations have the potential to revolutionize poultry vaccination, offering safer, more effective, and globally deployable strategies to safeguard poultry health and productivity.