Yifeng Qin

Goose astrovirus (GAstV) affects goslings under three weeks old, leading to visceral gout. Currently, no effective drugs or vaccines exist, and its pathogenic mechanisms are not well understood. In the present study, two GAstV strains, designated as GDFS and GXDK, were isolated from clinically affected geese, and their complete genome sequences were successfully amplified. Sequence alignment and phylogenetic analyses indicated that both isolates belong to GAstV genotype II, with GDFS and GXDK being most closely related to subgenotypes IId and IIc, respectively. Pathogenicity assessments demonstrated that infection of one-day-old goslings with the GDFS and GXDK strains resulted in severe clinical manifestations, causing pathological damage to the liver, spleen, and kidneys, with survival rates of 50% and 37.5%, respectively. The infection also led to increased serum uric acid levels, upregulation of kidney injury markers and inflammatory factors, and downregulation of antioxidant factor expression. To assess the protective effects of three anti-inflammatory agents—luteolin, naringin, and quercetin—against GAstV infection, one-day-old goslings were administered these compounds orally for 7 consecutive days following GAstV exposure. The findings indicated that treatment with all three anti-inflammatory agents significantly mitigated the clinical manifestations and pathological damage associated with GAstV infection, reduced mortality rates, facilitated weight gain in goslings, and decreased both viral shedding and tissue viral loads. Furthermore, the administration of these drugs markedly lowered serum uric acid levels and renal inflammatory factor expression, while enhancing the expression of antioxidant factors. This study provides insights into the genetic evolution, pathogenic mechanisms, and clinical management of GAstV.

Getah virus (GETV), a mosquito-borne arbovirus of the Alphavirus genus, poses an emerging threat to livestock economies and public health, underscored by its expanding host range and association with recent outbreaks of heightened virulence. While the functional significance of the 3' untranslated region (3'UTR) in alphavirus biology is recognized, its specific role in GETV remained undefined. Herein, we elucidate the virological functions of the GETV 3'UTR through a reverse genetics approach, generating a panel of viruses with targeted deletions. We demonstrate that the GETV 3'UTR is remarkably plastic, tolerating a consecutive deletion of up to 310 nucleotides while remaining viable. Deletion of conserved repeat sequence elements (RSEs) induced a cell-type-specific replication deficiency in vitro and significantly attenuated virulence in a murine model. A comprehensive deletion mutant (rGETV-KO310) exhibited further impaired replication kinetics in vitro and was profoundly attenuated in vivo, eliciting only transient morbidity with no mortality in both neonatal and weaned mice. Furthermore, this mutant displayed a significant defect in early colonization within mosquito vectors, indicating a role in vector competence. Comparative transcriptomic profiling of knee joints revealed that attenuation correlates with the altered modulation of critical host immune responses, notably the interferon and MAPK signaling pathways. Collectively, these findings establish the GETV 3'UTR as a pivotal regulator of viral fitness, pathogenesis, and transmission. This work provides a foundational rationale for the strategic development of live-attenuated vaccine candidates based on targeted 3'UTR attenuation.

Mammalian orthoreoviruses (MRVs) infect a wide range of animal hosts, yet epidemiological data from southern China remain limited. Here, we performed regional screening of diarrheic cattle in Guangxi, China, from 2023 to 2025. Using L1-targeted RT-PCR, MRV was detected in 8.4% (15/178) of fecal specimens collected across eight prefectures, with a higher detection rate during the cool (autumn–winter) season (October–March). We obtained two complete S1 segments, assigning one Guangxi strain to MRV1 and the other to MRV3. Phylogenetic analysis of L1 sequences indicated a single local lineage nested within a broader multi-host cluster, which was consistent with segment reassortment. σ1 protein alignment revealed a conserved central/C-terminal scaffold and a variable distal head; notably, the MRV3 σ1 sequence contained an extended ~360–390 aa region compared with MRV1. Overall, these findings provide an epidemiological baseline for Guangxi cattle, integrating detection rate, serotype context, and seasonality to support targeted, seasonally informed surveillance and MRV risk assessment.

Porcine astrovirus (PAstV) is globally prevalent in swine and is associated with diarrhea and encephalitis in piglets, posing a threat to porcine health. However, its pathogenic mechanisms remain poorly understood. This study used the PAstV1-GX1 strain to infect PK-15 cells, revealing that the virus induces significant apoptosis, with late apoptotic cells reaching 41.2% at 24 hours post-infection. The infection activates caspase-9 and caspase-3, but not caspase-8, and causes mitochondrial damage, indicating apoptosis via the mitochondrial pathway. The apoptosis inhibitor Z-VAD-FMK reduced viral replication, while apoptosis inducer ABT-263 enhanced it at later stages. The nsP1a/3 protein, which interacts with MAVS and localizes to mitochondria, was identified as key in inducing apoptosis. Its 3C-like serine protease domain likely mediates this interaction. Knocking down MAVS reduced apoptosis and increased early-stage replication but decreased it later. Overexpressing MAVS increased apoptosis and decreased replication. Furthermore, we observed that the expression of nsP1a/3 resulted in the cleavage of MAVS and the suppression of the type I interferon (IFN) response. Notably, treatment with Z-VAD-FMK did not influence nsP1a/3-mediated MAVS cleavage or type I IFN inhibition, suggesting that the induction of apoptosis and MAVS cleavage are distinct processes. By employing site-directed mutagenesis to substitute alanine for the catalytic triad residues (His ₄₅₉ , Asp ₄₈₇ , and Ser ₅₄₉ ) of the 3C-like serine protease, we significantly reduced the ability of nsP1a/3 to induce apoptosis, cleave MAVS, and suppress the type I IFN response, underscoring the essential role of protease activity in these functions. Furthermore, the use of a serine protease inhibitor markedly decreased PAstV replication. These findings provide significant insights into the pathogenesis of PAstV and establish a foundation for the development of novel antiviral therapies.

Porcine astrovirus (PAstV) is an important and widespread pathogen in swine, linked to diarrheal outbreaks and extraintestinal disease. How PAstV enters host cells has remained unclear, and no cellular factor has been defined for PAstV entry. Here, a genome-wide CRISPR–Cas9 loss-of-function screen in porcine epithelial cells identifies Annexin A1 (ANXA1) as a host factor that facilitates PAstV entry. Genetic ablation or pharmacological/antibody blockade of ANXA1 reduces binding, lowers early viral RNA and capsid signals, and delays the rise of progeny, whereas re-expression restores susceptibility. Biochemical assays and surface plasmon resonance indicate a direct interaction between ANXA1 and the acidic C-terminal domain of the PAstV ORF2 capsid protein, and imaging shows ANXA1 co-localizes with incoming particles at the cell surface and supports attachment and uptake. Loss of ANXA1 does not alter infection by the non-astrovirus panel tested, indicating selectivity for PAstV under our conditions. Notably, infection is reduced but not abolished in ANXA1-deficient cells, consistent with additional entry factors acting alongside ANXA1. These findings position ANXA1 as an entry cofactor for PAstV and provide a mechanistic basis to refine models of astrovirus host-cell recognition.

Porcine Teschovirus (PTV) is a highly prevalent pathogen within swine populations, primarily associated with encephalitis, diarrhea, pneumonia, and reproductive disorders in pigs, thereby posing a significant threat to the sustainable development of the pig farming industry. In this study, a novel strain of PTV was isolated from the feces of a pig exhibiting symptoms of diarrhea, utilizing PK-15 cell lines. The structural integrity of the viral particles was confirmed via transmission electron microscopy, and the viral growth kinetics and characteristics were evaluated in PK-15 cells. High-throughput sequencing facilitated the acquisition of the complete viral genome, and subsequent phylogenetic analysis and full-genome alignment identified the strain as belonging to the PTV 2 genotype. Further investigation revealed that infection with the PTV-GXLZ2024 strain induces phosphorylation of the eukaryotic translation initiation factor 2α (eIF2α) in PK-15 cells, indicating activation of the unfolded protein response (UPR) through the PERK pathway, with minimal involvement of the IRE1 or ATF6 pathways. Notably, ATF4 protein expression was progressively downregulated throughout the infection, while downstream CHOP protein levels remained unchanged, indicating an incomplete UPR induced by PTV-GXLZ2024. Furthermore, PERK knockdown was found to enhance the replication of PTV-GXLZ2024. This study provides critical insights into the molecular mechanisms underlying PTV pathogenesis and establishes a foundation for future research into its evolutionary dynamics and interactions with host organisms.

Porcine astrovirus (PAstV) poses a major risk to the pig industry by causing diarrhea in suckling piglets. Despite its global prevalence and five genotypes, the virus’s pathogenic mechanism is not well understood due to difficulties in isolating and culturing it in vitro. Studying PAstV from clinical samples and its interaction with host cells is crucial for understanding its pathogenesis and developing antiviral treatments. To isolate porcine astrovirus (PAstV) from clinical specimens, fecal samples from PAstV-positive pigs were collected in August 2018, inoculated into PK-15 cells, and subjected to three successive blind passages. The in vitro growth characteristics of the isolated strain were subsequently evaluated, and the morphology of the virus particles was examined through electron microscopy. The complete genome sequence of the isolated strain was determined, followed by sequence alignment, homology analysis, phylogenetic analysis, and recombination analysis. To investigate the induction of reactive oxygen species (ROS) production in PK-15 cells infected with the isolated strain, the cells were infected, and ROS production was quantified using the MitoSOX probe. Furthermore, the expression levels of the antioxidant factors Nrf2 and HO-1 were analyzed via Western blotting. Mitochondrial damage resulting from PAstV infection was observed using transmission electron microscopy, and the effect of PAstV infection on mitochondrial membrane potential was assessed using the JC-1 probe. Finally, the impact of ROS on PAstV replication was explored using IFA and RT-qPCR. In this study, a strain of PAstV was isolated from porcine fecal samples, demonstrating an ability to adapt effectively to PK-15 cells with a viral titer reaching up to 10^7.85 TCID50/mL. Genetic evolution analysis classified the isolated strain as PAstV5, revealing high genetic homology with other representative PAstV5 strains. The isolated strain was designated as PAstV5-GX2. Sequence alignment identified 11 consecutive amino acid deletions at the 3’ end of ORF1a in the PAstV5-GX2 strain, resulting in alterations to the three-dimensional structure of the nsp1a/4 protein. Further investigation indicated that PAstV infection in PK-15 cells enhances mitochondrial ROS production and diminishes the protein expression levels of the antioxidant molecules Nrf2 and HO-1. Concurrently, PAstV infection induces mitochondrial swelling, cristae rupture, and vacuolization, along with a reduction in mitochondrial membrane potential. Through the application of H2O2 and NAC to modulate cellular ROS levels, it was determined that ROS can facilitate viral replication. Our study successfully isolated a novel strain of PAstV5 characterized by an 11-amino acid deletion in the nsp1a protein, leading to significant alterations in the three-dimensional structure of the nsp1a/4 protein. This strain was observed to induce the production of mitochondrial ROS, downregulate the expression of Nrf2 and HO-1, and cause mitochondrial damage. Furthermore, the generation of mitochondrial ROS was found to facilitate the replication of PAstV. These findings offer valuable insights into the genetic evolution and pathogenic mechanisms of PAstV.