Enterovirus 71 (EV-A71), a neurotropic member of the Picornaviridae family, is a positive-strand RNA virus comprising of seven recognized genogroups (A-G) and has caused significant outbreaks of hand, foot, and mouth disease worldwide. Despite prior identification of D and G genogroups in India, comprehensive full-genome characterization of these indigenous lineages remains unreported. We performed next-generation sequencing (NGS) and molecular phylogenetic analyses on two Indian isolates from acute flaccid paralysis cases: R13223-IND-02 (genogroup D) and V11-2209-01 (genogroup G). The complete genomes generated through NGS were aligned with publicly available full-length and partial EV-A71 sequences using MAFFT, and phylogenetic trees were constructed employing the maximum-likelihood method. Amino acid variations were then compared across the genogroups, as well as with prototype and neurovirulent reference strains. Phylogenetic reconstruction revealed robust clustering of these strains within distinct clades (bootstrap support ≥ 99%)", divergent from globally prevalent genogroups B and C. Both D and G genogroups appear geographically restricted to India, while genogroup D persists as an endemic lineage. Comparative genomic analyses demonstrated extensive nucleotide divergence, including numerous non-synonymous substitutions across both structural (VP1-VP4) and non-structural (2A-3D) coding regions. An E-Q substitution at amino acid position 145 in the VP1 structural protein was detected in both D and G genogroups, a site functionally linked to receptor binding and mouse virulence. The findings highlight the evolutionary independence and sustained circulation of D and G genogroups in India, suggesting a unique regional evolutionary trajectory. The implications hold significant global relevance, offering valuable insights for molecular surveillance, advancing pathogenesis research, and supporting the development of genogroup-specific vaccine strategies tailored to diverse epidemiological landscapes. This study is the first to report the complete genome of EV-A71 D and G genotypes in India, and its unique mutation characteristics provide a direct target for the development of region-specific vaccines.

Intradermal (ID) immunization is a potent vaccination strategy, but its potential is limited by the lack of adjuvants that can effectively enhance immune responses while minimizing local skin reactogenicity. To develop and evaluate a novel composite nano-emulsion adjuvant, designated VP, for enhancing the efficacy of intradermal vaccination against swine influenza virus (SIV). A novel adjuvant VP, formulated with squalene, sea buckthorn oil, and the TLR3 agonist Poly(I: C), was designed. Its physicochemical properties (particle size, zeta potential, viscosity) were characterized. The immunogenicity and protective efficacy of the VP-adjuvanted inactivated H3N2 vaccine were systematically evaluated in mice, comparing intradermal (ID) and intramuscular (IM) routes. Assessments included humoral immunity (serum and bronchoalveolar lavage fluid (BALF) IgG/HAI titers, duration), cellular immunity (splenic T cell subsets, cytokine profiles), and protection against homologous viral challenge (viral load, lung pathology, weight loss). Local skin reactogenicity and inflammatory responses were also investigated. The VP adjuvant exhibited a potent immune-stimulatory effect, comparable to commercial adjuvants. The VP/H3N2 formulation formed a stable nano-emulsion with an average particle size of ~ 137nm, a near-neutral surface charge, and low viscosity (~ 1.3cP), facilitating antigen transport to skin-draining lymph nodes. Immunization induced a robust, Th1-biased immune response characterized by high IgG2a/IgG1 ratios and elevated IFN-γ secretion. Notably, the VP-adjuvanted vaccine elicited the highest proportions of IFN-γ⁺ CD4⁺, IFN-γ⁺ CD8⁺and memory-type CD44⁺ CD4⁺ T cells among all experimental groups. ID administration was superior to IM, yielding significantly higher and more durable serum/BALF antibody titers and longer-lasting immunity. VP-adjuvanted vaccination provided protection against challenge, with minimal lung pathology and markedly reduced viral loads. Crucially, ID immunization with VP elicited only a moderate, transient local inflammatory response with rapid absorption and no significant adverse skin reactions. Mechanistic studies revealed that VP functioned by upregulating key chemokines (e.g., CX3CL1, CCL19) at the injection site, significantly enhancing antigen uptake by dendritic cells in vitro, and promoting targeted antigen delivery to draining lymph nodes in vivo. This study successfully developed a novel composite nano-emulsion adjuvant, VP, which demonstrated high efficacy in intradermal SIV vaccination by potently enhancing both humoral and cellular immunity, providing durable protection, and maintaining an acceptable safety profile. The adjuvant mechanism involves enhanced local immune activation, promotion of Dendritic cells (DCs) phagocytosis, and improved lymphoid trafficking. These findings provide a theoretical and practical foundation for developing next-generation influenza vaccine adjuvants.

Chronic hepatitis B virus (HBV) infection affects nearly 300million people worldwide and remains a leading cause of the global cancer burden. While its causal relationship with hepatocellular carcinoma (HCC) is well established, accumulating epidemiological and mechanistic evidence suggests that HBV may also contribute to the development of extrahepatic malignancies, including gastric, colorectal, pancreatic, lymphoid, and respiratory cancers. Cohort studies and meta-analyses consistently report an increased risk in individuals infected with HBV, but causality remains controversial due to confounding factors such as coinfection, lifestyle factors, and genetic susceptibility. Possible mechanisms include viral DNA integration into the host genome, HBV X protein (HBx)-mediated activation of oncogenic signaling pathways (PI3K-Akt, Wnt), epigenetic modifications, and alterations in the immune microenvironment that promote tumor immune evasion. Advances in biomarker discovery, imaging technologies, and antiviral and targeted therapies offer opportunities for early detection and improved management of HBV-related cancers. This review summarizes the current knowledge on the epidemiology, pathophysiology, diagnostic strategies, and treatment approaches of HBV-related extrahepatic malignancies, as well as the current controversies, with the aim of guiding future research and clinical practice.

Our study aims to investigate the dynamic changes in plasma/serum EBV-DNA levels and the cytokines IL-10 and IFN-γ during early chemotherapy. This will help predict refractory EBV-HLH and guide more personalized treatment strategies. This retrospective, single-centre cohort investigation included 117 EBV-HLH; out of these, 48 had comprehensive paired data before and after induction treatment. The median age was 3.86 years. Patients were classified based on pre-treatment plasma/serum EBV-DNA levels into high-load (≥ 5.51 × 104 copies/mL) and low-load cohorts. Patients with high plasma/serum EBV-DNA loads demonstrated a higher prevalence of DIC (20.00% vs. 3.51%, OR = 7.15) at baseline. After a two-week treatment period, the decline in EBV-DNA was strongly correlated with reductions in IFN-γ (r = 0.443, P = 0.002) and IL-10 (r = 0.540, P < 0.001). Interestingly, in this study, we also found that children with a double-positive status (EBV+/IFN-γ + or EBV+/IL-10+) did not have the worst prognosis two weeks after initial treatment. However, children with HLH who are EBV (+) but cytokine (-) have a lower proportion of partial responses. Similarly, most children with HLH who are plasma or serum EBV-negative but cytokine-positive are also in the non-response period. In the early stages of treatment, monitoring plasma/serum free EBV-DNA, as well as IL-10 or IFN-γ indicators, and stratifying patients is an effective method to identify children with EBV-HLH who are prone to refractory disease. This approach is of great significance for guiding their subsequent treatment.

Hepatitis B virus (HBV) is highly contagious, primarily infected through mucous membranes or broken skin exposed to infected body fluids. Conventional injectable vaccines, which require cold chain storage and trained personnel, elicit systemic immunity but fail to establish effective immune protection at mucosal sites where HBV enters. Mucosal vaccines administered orally or intranasally can induce both mucosal and systemic immune responses, offering enhanced protection along with advantages such as ease of administration, no need for cold chain, and reduced reliance on healthcare workers. Given the critical potential of mucosal vaccines in addressing HBV transmission, this review systematically summarizes recent progress in mucosal HBV vaccine development. It covers the evolution of vaccine platforms, from early nasal sprays to advanced oral delivery systems utilizing plant-based antigens, synthetic nanomaterials, and exosomes derived from sources like milk. The advantages and challenges of these platforms are systematically analyzed, with particular attention given to exosome-based systems, which demonstrate excellent biocompatibility and strong potential for effective mucosal delivery. Furthermore, this review discusses future trends in the field, including engineering strategies for targeted delivery and scalable production. Ultimately, this review aims to bridge research and application by offering clear insights and directions to advance the development of practical mucosal HBV vaccines.

Siglec-1, also known as sialoadhesin (Sn) or CD169, is a product of the SIGLEC1 gene. A large body of work performed on cell culture systems concludes that Siglec-1 is a primary receptor for porcine reproductive and respiratory syndrome virus (PRRSV) isolates in the genotype 1 or PRRSV-1 group. In this study, primary cultures of PAMs from SIGLEC-1 knockout (KO) pigs showed resistance to infection using both PRRSV-1 and PRRSV-2 isolates, which is consistent with previous observations. However, infection of KO and WT pigs with a PRRSV-1 isolate, SD01-08, resulted in viremia in both groups. Interestingly, virus nucleic acid levels in sera were significantly greater in the KO pigs at 21 and 28 days after infection. Mean virus load, calculated as area under the viremia curve over the infection period, was also significantly greater for the KO group. At the level of the pig, Siglec-1 as a receptor for PRRSV may not be biologically relevant. The increased viremia observed for the KO pigs may reflect a role for Siglec-1 in the regulation of the immune response to PRRSV-1.

Zika virus (ZIKV) remains a significant global health threat due to its association with severe neurological disorders, yet no specific treatments are available. Ouabain (OUA) has demonstrated antiviral and immunomodulatory properties, but its mechanisms against ZIKV in neural cells are not fully understood. Here, we investigated the effects of OUA on ZIKV-infected SH-SY5Y cells, a model for undifferentiated neurons, and employed in silico analyses to elucidate its protective mechanisms. OUA exhibited potent antiviral activity, reducing ZIKV titers by up to 99.9% without cytotoxicity (selectivity index > 25). Additionally, OUA decreased the ZIKV-induced production of the pro-inflammatory cytokines IL-6 and TNF-α. Mechanistically, OUA suppressed ZIKV-induced NF-κB phosphorylation, providing a basis for its anti-inflammatory effects. Furthermore, OUA treatment restored the phosphorylation mTOR, ERK, and p38, important key neurogenesis-related proteins compromised by ZIKV infection. Moreover, both ZIKV and OUA additively increased SRC phosphorylation, a pathway previously linked to OUA's antiviral activity. In silico analyses predicted that OUA modulates numerous genes and proteins involved in cellular responses to viral infections. Collectively, our findings suggest a new mode of action for OUA in an undifferentiated neuronal cell model.

Understanding the genetic evolution of HIV-1 Transmitted/Founder (T/F) virus is crucial for developing effective treatment and prevention strategies due to its rapid mutation and recombination rates. This study compared the genetic diversity of 24 contemporary T/F viruses collected between 2016 and 2021 in Uganda and Kenya with 29 historical T/F sequences sampled between 2006 and 2011. Subtype analysis based on near-full-length (NFL) HIV-1 T/F genomes revealed that 57.1% (12/21) of contemporary viruses were recombinants, predominantly involving Subtype A1, D, and increasing Subtype C, with 33.3% (7/21) being A1D recombinants (A1 > D) and 19% (4/21) classified as complex recombinants involving three or more subtypes. Historical viruses showed a similar overall proportion (69%) but were mainly A1D mosaics (D > A1) with recombination confined primarily to the envelope region. In contrast, contemporary viruses shifted towards more complex recombinant patterns affecting additional genomic regions, including pol and accessory genes. Phylogenetic analysis demonstrated that contemporary viruses clustered into distinct, well-supported (98% bootstrap) sub-branches, suggesting divergency attributed to an imbalance in their proportions of subtype A1 and D sequences as well as a different content of A1 and D segments in the A1/D mosaic recombinants. These findings underscore the dynamic and shifting nature of HIV-1 genetic diversity in East Africa, highlighting the need for continuous molecular surveillance and region-specific treatment guidelines.

Rift Valley fever virus (RVFV) has mainly been reported in African countries, and molecular diagnosis is performed using nucleic acid amplification tests. Nucleic acid reference materials (RMs) are necessary for the performance evaluation and quality assessment of molecular diagnosis of Rift Valley fever. However, metrological certified RMs for RVFV nucleic acids are currently unavailable. In this study, RVFV RNA RMs (KRISS 111-10-537, 538, and 539) were developed from in vitro transcribed RNA containing a three-segment genome, including the L, M, and S segments. The RNA copy numbers of the L, M, and S segments of RMs were measured using reverse-transcription droplet digital PCR (RT-ddPCR), an advanced technology that enables the absolute quantification of viral genetic material. In the homogeneity analysis, the copy number values were measured to be from 7.82 × 104 to 2.51 × 106 copies/µl, and the consistency between different bottles of these RMs showed variation of only 4.0-6.7%. These reference materials demonstrated excellent stability, remaining stable for up to 14 days at 4°C and at -80°C for 12 months. This stability and consistency ensure that laboratories worldwide can rely on these materials for accurate testing. RMs can help reduce false positives and negatives in RVFV molecular tests by providing accurate reference values for target viral gene copy numbers, ultimately contributing to better diagnosis and control of this viral disease.