Sheng-Li Ming

Feline calicivirus (FCV) is a highly heterogeneous pathogen and a major cause of feline upper respiratory tract disease, highlighting the need for continuous surveillance of its genetic diversity and pathogenic characteristics. In this study, we isolated and comprehensively characterized a newly isolated FCV strain, HN/ZZ/2025, from cats at a feline trading market in Zhengzhou, China, and systematically evaluated its molecular features, in vitro replication characteristics, physicochemical properties, and pathogenicity in cats. Phylogenetic analysis classified HN/ZZ/2025 as genotype GI. The isolate replicated efficiently in CRFK, F81, and Fc3Tg cells, reaching peak titers of 10^7.18, 10^7.50, and 10^5.89 TCID₅₀/0.1 mL, respectively, and exhibited typical calicivirus-like particles with diameters of 35–40 nm. Complete genome analysis showed that HN/ZZ/2025 shared the highest nucleotide and amino acid sequence identities of 85.7% and 62.8%, respectively, with the closely related Chinese FCV strain CH-JL4, and revealed distinct amino acid variations within the hypervariable E region of the VP1 capsid protein. Experimental infection of cats (n = 3/group) resulted in pyrexia, with rectal temperatures reaching 39.8–40.2 °C, weight loss, oral ulceration, and persistent viral RNA shedding from 1 to 21 days post-infection. Viral RNA and VP1 antigen were detected in the lungs, trachea, kidneys, and spleen, indicating systemic dissemination and broad tissue distribution. Although no mortality occurred during the observation period, the observed clinical signs, viral dissemination, and histopathological lesions indicate that HN/ZZ/2025 is capable of causing clinically evident disease in experimentally infected cats. These findings provide useful insights into the molecular epidemiology, tissue tropism, and host–virus interactions of circulating FCV strains and establish HN/ZZ/2025 as a useful isolate for future studies of FCV genetic diversity and pathogenesis.

Feline bocavirus (FBoV) is an emerging enteric virus associated with gastrointestinal diseases in cats and has attracted increasing attention in feline health. However, no commercial vaccine is currently available for the prevention and control of FBoV infection. VP2 is the major capsid protein of FBoV and represents a promising target for vaccine development. In this study, the FBoV VP2 protein was expressed using the insect baculovirus expression system. The purified VP2 protein self-assembled into virus-like particles (VLPs), which were formulated with Alum, ISA 206, or GEL 02 adjuvants to prepare VP2 VLP vaccines. The immunogenicity, cellular immune responses, antigen uptake, biodistribution, germinal center responses, and safety of the vaccines were evaluated in BALB/c mice. The results showed that all VP2 VLP vaccine formulations induced VP2-specific IgG antibodies and neutralizing antibodies, promoted B- and T-lymphocyte activation, enhanced dendritic cell maturation, and stimulated germinal center-related immune responses. Among the tested formulations, VP2+GEL 02 induced the strongest immune responses and showed favorable safety in mice. These findings demonstrate that FBoV VP2 exhibits favorable immunogenicity and represents a promising vaccine antigen for further development against feline bocavirus.

Viral infection triggers a robust DNA damage response (DDR), reshaping the host chromatin landscape to facilitate viral replication. Here, we uncover a novel mechanism by which alphaherpesviruses exploit the DDR pathway. We demonstrated that herpes simplex virus 1 (HSV-1) and pseudorabies virus (PRV) induced selective degradation of class I histone deacetylases (HDAC1/2), leading to histone hyperacetylation and subsequent DDR activation. Strikingly, viral infection promoted nuclear export of HDAC1/2, followed by MDM2-mediated K63-linked polyubiquitination and proteasomal degradation in the cytoplasm. Pharmacological inhibition of either DDR signaling or HDAC1/2 nuclear export significantly affected viral replication in vitro and in vivo. Our findings reveal a unique viral strategy to hijack host epigenetic regulation for efficient replication, and identify potential therapeutic targets for alphaherpesvirus infections.

Viral infection triggers a robust DNA damage response (DDR), reshaping the host chromatin landscape to facilitate viral replication. Here, we uncover a novel mechanism by which alphaherpesviruses exploit the DDR pathway. We demonstrated that herpes simplex virus 1 (HSV-1) and pseudorabies virus (PRV) induced selective degradation of class I histone deacetylases (HDAC1/2), leading to histone hyperacetylation and subsequent DDR activation. Strikingly, viral infection promoted nuclear export of HDAC1/2, followed by MDM2-mediated K63-linked polyubiquitination and proteasomal degradation in the cytoplasm. Pharmacological inhibition of either DDR signaling or HDAC1/2 nuclear export significantly affected viral replication in vitro and in vivo. Our findings reveal a unique viral strategy to hijack host epigenetic regulation for efficient replication and identify potential therapeutic targets for alphaherpesvirus infections.

The 3,4-dihydropyrimidin-2(1H)-one (DHPM) scaffold possesses diverse biological activities and chemical tunability, allowing structural modifications to modulate antiviral, anticancer, and anti-inflammatory effects. In this study, a series of DHPM derivatives with varied substituents were designed and synthesized, and their structures were characterized by ¹H NMR, ¹³C NMR and HRMS. Their antiviral activities against pseudorabies virus (PRV) and vesicular stomatitis virus (VSV) were evaluated. In vitro assays revealed that several compounds exhibited significant antiviral effects, with 4bf (SI = 243.08 against PRV), 4ce (SI = 196.4 against VSV), and 4be (SI = 124.2 against PRV; SI = 181.1 against VSV) showing the most potent activity. Further studies demonstrated effective inhibition of viral titers, and Western blot and qRT-PCR analyses confirmed downregulation of viral proteins and related genes. Cytotoxicity tests indicated that 4bf, 4ce, and 4be had CC₅₀ values of 270.0, 147.1, and 190.9 μg/mL, respectively, suggesting favorable safety profiles. In vivo experiments showed that 4bf, without affecting normal growth, alleviated PRV-induced pulmonary inflammation and tissue damage, and improved survival in mice. Taken together, DHPM-based compounds demonstrate promising potential as candidate antiviral agents, warranting further development.

Toll-like receptor 7 (TLR7) agonism offers a promising avenue for antiviral intervention. This study characterizes AXC-715, a novel small-molecule agonist that selectively targets TLR7 to elicit broad-spectrum antiviral effects. Structural analysis of the AXC-715–hTLR7 complex (PDB ID: 5GMH) elucidates the molecular basis of receptor activation. AXC-715 occupies the interface of TLR7 monomers, establishing critical hydrogen bonds with D555 and T586, alongside π-π and π-alkyl interactions with F408, V381, and L557. These interactions effectively promote and stabilize the active TLR7 dimeric conformation. Functionally, AXC-715 activates NF-κB signaling in a P65-dependent manner without inducing cytotoxicity in PK-15 or THP-1 cells. In vitro assays demonstrated that AXC-715 potently inhibits the replication of both pseudorabies virus (PRV) and vesicular stomatitis virus (VSV) by specifically impairing viral replication, distinct from adsorption, entry, assembly, or release processes. The antiviral effect was abolished in TLR7-knockout PK-15 cells, confirming the strict dependence of AXC-715 on on-target TLR7 signaling. These findings highlight AXC-715 as a potent TLR7 agonist that stabilizes receptor dimerization to inhibit viral replication, providing a valuable framework for developing TLR7-based antiviral therapeutics.

Porcine reproductive and respiratory syndrome virus (PRRSV), a highly contagious pathogen in swine, poses significant economic challenges to global pork production. This study elucidated the regulatory interplay between PRRSV infection and the pentose phosphate pathway (PPP), a critical metabolic axis for anabolism. Comparative metabolomic profiling of porcine alveolar macrophages (PAMs) pre- and post-PRRSV infection demonstrated marked upregulation of PPP activity, concomitant with elevated levels of nucleotide biosynthesis. This metabolic shift was driven by PRRSV-induced upregulation of glucose-6-phosphate dehydrogenase (G6PD), the PPP's rate-limiting enzyme. Mechanistic investigations revealed that PRRSV infection stimulated hypoxia-inducible factor 1α (HIF-1α) expression, which transcriptionally activates G6PD. Genetic silencing of HIF-1α abolished PRRSV-mediated G6PD induction. Furthermore, reactive oxygen species (ROS) accumulation was identified as the upstream regulator of HIF-1α activation during PRRSV infection. Pharmacological ROS scavenging disrupted the ROS/HIF-1α/G6PD signaling cascade, diminished NADPH and reduced glutathione production, and consequently attenuated viral proliferation. These results established that PRRSV exploited the ROS/HIF-1α axis to reprogram host glucose metabolism through PPP potentiation, creating a biosynthetic environment conducive to viral propagation.

Porcine reproductive and respiratory syndrome virus (PRRSV), an enveloped single-stranded positive-sense RNA virus, poses a significant threat to global swine production. Despite the availability of modified live virus and inactivated vaccines, their limited efficacy and safety concerns highlight the urgent need for novel antiviral therapeutics. This study aimed to investigate the molecular mechanisms by which lycopene inhibits PRRSV replication. Initial assessments confirmed that lycopene did not adversely affect cellular viability, cell cycle progression, or apoptosis. Using fluorescence microscopy, flow cytometry, immunoblotting, quantitative real-time PCR (qRT-PCR), and viral titration assays, lycopene was shown to exhibit potent antiviral activity against PRRSV. Mechanistic studies revealed that lycopene suppresses reactive oxygen species (ROS) production, which is critical for PRRSV proliferation. Additionally, lycopene attenuated PRRSV-induced inflammatory responses, as demonstrated by immunoblotting, ELISA, and qRT-PCR assays. These findings suggest that lycopene inhibits PRRSV replication by modulating ROS levels and mitigating inflammation, offering a promising avenue for the development of antiviral therapeutics. This study provides new insights and strategies for combating PRRSV infections, emphasizing the potential of lycopene as a safe and effective antiviral agent.

Feline panleukopenia virus (FPV), the etiological agent of a highly contagious multispecies disease, demonstrates concerning phylogenetic divergence that compromises vaccine cross-protection. This study aimed to characterize a novel FPV strain through integrated virological and molecular analyses to assess epidemiological implications. From seven clinical specimens obtained from feline hosts with panleukopenia in Henan Province, China, we isolated FPV ZZ202303 using an F81 cell culture coupled with PCR verification, demonstrating potent cytopathic effects (TCID₅₀: 10^−5.72/0.1 mL) and rapid replication kinetics (viral peak at 12–24 h post-infection). Comparative virulence assessments revealed a 1.8- to 2.3-fold greater pathogenicity versus contemporary field strains (2021–2023). Phylogenetic reconstruction based on complete VP2 gene sequences positioned FPV ZZ202303 within an emerging clade sharing 97.5–98.2% identity with canine parvovirus strains versus 98.8–99.7% with FPV references, forming a distinct cluster (bootstrap = 94%) diverging from vaccine lineages. Critical structural analysis identified a prevalent I101T mutation (89.13% prevalence) in the VP2 capsid protein’s antigenic determinant region, with molecular modeling predicting altered surface charge distribution potentially affecting host receptor binding. Our findings substantiate FPV ZZ202303 as an evolutionarily divergent strain exhibiting enhanced virulence and unique genetic signatures that may underlie vaccine evasion mechanisms, providing critical data for updating prophylactic strategies against this economically impactful pathogen.