H5Nx highly pathogenic avian influenza viruses pose persistent threats to poultry, wildlife, and public health. Over the past two decades, their geographic and host ranges have expanded across migratory networks whose epidemiological connectivity has become increasingly apparent through recent surveillance and genomic analyses. To elucidate these dynamics, we conduct long-term nationwide wild-bird surveillance in China, integrating active and passive monitoring. Our analyses reveal the maintenance, reassortment, and transmission of H5Nx viruses in wild birds, highlighting the value of sustained surveillance in capturing viral evolution. We identify distinct ecological patterns among major clades, with 2.3.4.4b showing the widest distribution and acting as the main lineage mediating intercontinental spread. Since 2020, most 2.3.4.4b viruses detected in wild birds in China have clustered with lineages originating outside China, consistent with repeated reintroduction rather than sustained local circulation. This shift underscores the growing role of migratory connectivity in shaping global viral exchange and the need for coordinated international active surveillance.

The Qinghai-Tibet Plateau serves as a critical hub along the Central Asian Flyway (CAF) and a recognized hotspot for the emergence of highly pathogenic avian influenza (HPAI) viruses. Despite recurrent outbreaks, the migratory dynamics of key reservoir species, such as the Brown-headed Gull (Chroicocephalus brunnicephalus) and their potential contributions to viral dissemination remain poorly understood. Here, we integrated highresolution GPS telemetry with Bayesian discrete phylogeographic analyses to investigate the potential association between migration and HPAI H5Nx dissemination. Based on tracking data from 11 individuals, we identified 5 major life-history stages and 12 important stopover sites used during migration, including 6 in autumn and 6 in spring, and characterized their spatiotemporal distribution patterns. Phylogenetic reconstruction showed that three independent introductions of HPAI H5Nx viruses occurred on the Qinghai-Tibet Plateau between 2021 and 2024, all involving strains associated with Brown-headed Gulls and classified into the 2021-H5N8 I, 2021-H5N8 II, and 2022-H5N1 clusters. These viral clusters were distributed primarily along the CAF and the East Asian-Australasian Flyway (EAAF), with diffusion patterns broadly consistent with the spatiotemporal dynamics of migratory birds. Notably, the spread of the 2022-H5N1 cluster along the CAF was highly concordant with the migratory route and phenology of Brown-headed Gulls, while host transition analysis suggested that gulls may serve as bridging hosts in interspecies transmission. Together, these findings suggest that Brown-headed Gulls may contribute to the cross-regional dissemination and interspecies transmission of HPAI H5Nx viruses, and highlight the value of combining tracking data with viral genomics for cross-border surveillance.

H13 and H16 subtype avian influenza viruses (AIVs) typically infect Charadriiformes, are widely distributed throughout coastal regions worldwide, and pose a risk of spillover to mammals. Systematic research on the epidemiology, transmission dynamics, and biological characteristics of these subtypes remains limited. To address this gap, we analyzed 20 years of wild bird influenza surveillance data from China integrated with global influenza database information to reconstruct the global spatiotemporal distribution, transmission dynamics and public health implications of H13 and H16. During influenza surveillance, 28 H13 and 19 H16 viruses were isolated. The phylogenetic trees for the H13 and H16 viruses revealed that both subtypes could be classified into three distinct groups. Viruses from H13 Group A, H13 Group C, and H16 Group C demonstrated frequent genetic exchanges and intercontinental transmission on a global scale. Mapping host migration revealed overlap between virus spread and host migration pathways. Our results suggest that host migration is a key driver of widespread distribution, cross-regional spread, and gene exchange for some H13 and H16 lineages. Virus isolates exhibit high genetic diversity with rich genotypic variation. Most isolates carry mammalian-adaptive mutations, such as the G228S mutation in the HA protein. H13 and H16 isolates of multiple genotypes infected mice without prior adaptation and exhibited varying tissue tropism. In summary, these findings indicate that host migration patterns are closely associated with the evolution of H13 and H16 AIVs. The potential risk of mammalian infection is highlighted, as viruses carrying mammalian-adaptive mutations may lead to new infection cases.

Respiratory tract infections caused by various pathogens remain a significant public health concern due to their high prevalence and potential for severe complications. This study systematically analyzed the epidemiological characteristics of six common respiratory pathogens-Chlamydia pneumoniae (CP), Mycoplasma pneumoniae (MP), Adenovirus (AdV), Influenza A virus (FluA), Influenza B virus (FluB), and Respiratory Syncytial Virus (RSV)-in patients from Sichuan Jinxin Xinan Women and Children's Hospital between April 2023 and March 2024. Throat swab samples were collected from a total of 22,717 individuals. Each sample was processed using the AUTOMOLEC 3000 analyzer and the PCR-fluorescent probe method. The results showed that 10,171 (44.8%) individuals tested positive for at least one pathogen. MP had the highest overall positive rate (21.83%), followed by FluA (17.50%) and FluB (14.84%). MP showed the highest mean monthly (average) positive rate (16.84% +/- 8.41). Significant differences were found between MP and AdV, CP and RSV in average positive rate (p < 0.05). Co-infection analysis revealed frequent associations between MP and AdV, MP and CP, and FluB with MP. Seasonal analysis indicated distinct peaks: FluA and FluB in winter, RSV in spring, and MP in summer, autumn and winter. Age-stratified analysis showed higher positivity rates of RSV in children aged 0-6 years, MP and CP in the 7-17 years group. Gender-based differences were only observed in RSV positive samples. These findings provide crucial insights into the prevalence and seasonal distribution of respiratory pathogens in Chengdu, offering valuable data to inform public health strategies in the post-COVID era.

Understanding the mechanisms of viral co-infection in natural host populations is crucial for predicting pathogen dynamics and cross-species transmission risks. This study focuses on the co-infection of avian influenza virus (AIV) and Newcastle disease virus (NDV) in wild ducks, combining field monitoring data, ecological niche modeling, and statistical analysis to reveal distribution patterns and driving factors. Organ samples collected from wild ducks in key migratory habitats revealed that AIV exhibits a broader ecological niche than NDV, with both viruses primarily replicating in the respiratory system. Ecological niche overlap modeling indicated a high degree of preference overlap between AIV and NDV in organ-specific microenvironments, suggesting that ecological compatibility is a prerequisite for co-infection. This study underscores the critical role of ecological and spatial compatibility in shaping viral co-infection patterns and provides a theoretical framework for understanding virus interactions in complex ecosystems.

Avian avulavirus (AAVV) is a significant pathogen affecting avian species, but research on its prevalence in wild birds in China has been relatively limited. In this study, active surveillance for AAVV was conducted in wild birds in China from 2003 to 2020. A total of 124,882 samples were collected from 26 provinces, and 220 AAVV-positive samples were identified, encompassing various serotypes including AAVV-1, -4, -6, -8, -9, -13, and -16. Notably, AAVV-9 isolates were reported for the first time in China through this study. Detailed genetic analysis of 148 representative strains revealed that 26 of them exhibited a polybasic amino acid residue at the F gene cleavage site, a molecular marker associated with virulent AAVV strains in chickens. The geographical isolation between the Old and New Worlds has led to the independent evolution of AAVVs in each region, resulting in distinct Eurasian and North American lineages. Our findings predominantly aligned with the Eurasian lineage. However, repeated detections of AAVVs of North American origin in wild birds in China suggests potential viral dispersal between North America and China, which warrants further investigation. Furthermore, geographical reconstruction of AAVV-4 occurrence indicated a possible transmission route from Europe to East Asia. The origin of AAVV-4 remains uncertain due to limited sequence data, underscoring the need for expanded surveillance and highlight the necessity for sustained, long-term epidemiological surveillance efforts.

This study introduces a novel diagnostic modality for the detection of feline panleukopenia virus (FPV) antibodies in feline serum by using fluorescent microsphere immunochromatographic test strips (FM-ICTS). Leveraging the inherent specificity of antigen-antibody interactions, the FM-ICTS approach demonstrates considerable potential for efficient and accurate FPV antibody detection within a short timeframe. Through rigorous sensitivity and specificity assessments, the method exhibits commendable diagnostic performance, exhibiting favourable accuracy and stability characteristics over an extended period. The clinical validation involving 84 samples underscores the reliability of the test by corroborating its outcomes with established haemagglutination inhibition (HI) assays. This innovative FM-ICTS framework emerges as a promising avenue for expedient and dependable disease diagnosis within the realm of veterinary science, offering implications for timely disease management and surveillance.

H6 avian influenza virus is widely prevalent in wild birds and poultry and has caused human infection in 2013 in Taiwan, China. During our active influenza surveillance program in wild waterfowl at Poyang Lake, Jiangxi Province, an H6N2 AIV was isolated and named A/bean goose/JiangXi/452-4/2013(H6N2). The isolate was characterized as a typical low pathogenic avian influenza virus (LPAIV) due to the presence of the amino acid sequence PQIETR↓GLFGAI at the cleavage site of the hemagglutinin (HA) protein. The genetic evolution analysis revealed that the NA gene of the isolate originated from North America and exhibited the highest nucleotide identity (99.29

H10 subtype avian influenza viruses (AIVs) have been isolated from wild and domestic avian species worldwide and have occasionally crossed the species barrier to mammalian hosts. Fatal human cases of H10N8 infections and the recent detection of human H10N3 infections have drawn widespread public attention. In this study, 25 H10Nx viruses were isolated from wild waterfowl in China during a long-term surveillance of AIVs. We conducted phylogenetic and phylogeographic studies of the hemagglutinin (HA) genes of global H10 viruses to determine the spatiotemporal patterns of spread and the roles of different hosts in viral transmission. We found the pattern of AIV transmission from wild birds to poultry to humans, and Anatidae have acted as the seeding population in the spread of the virus. Phylogenetic incongruence indicated complex reassortment events and our isolates were divided into eight genotypes (G1-8). We also found that the HA genes of the G8 viruses belonged to the North American lineage, indicating that intercontinental gene flow has occurred. Their receptor-binding specificity showed that the G1/4/5/6/7/8 viruses bind to both human-type α2,6-linked sialic acid receptors and avian-type α2,3-linked sialic acid receptors. Mouse studies indicated that the H10Nx isolates replicated efficiently in the respiratory system without preadaptation, but showed low pathogenicity in mice. The H10Nx isolates showed no (G2/4/7) or low pathogenicity (G1/3/5/6/8) in chickens, and the G6 and G8 viruses could be transmitted to chickens through direct contact. The asymptomatic shedding of these wild-bird-origin H10Nx isolates in chickens and their good adaptation in mice should increase the ease of their transmission to humans, and they therefore pose a threat to public health. Our findings demonstrate a further understanding of wild bird-origin H10 viruses and provide information for the continuous surveillance of H10 subtype viruses.

Porcine epidemic diarrhea virus (PEDV) is an acute and highly contagious porcine enteric coronavirus. It has caused serious economic losses of pig industry in China. Here we insolated a current PEDV field strain named GS2022, analyzed the characters of genetic variation and pathogenicity. The results demonstrated that the GS2022 strain was belong to a newly defined subgroup G2 d, forming an independent branch which mainly contains strains isolated in China from 2017 to 2023. Notably, there are multiple mutations and extensive N-glycosylation compared to CV777 strain and PT-P5 strain, therefore the structure of GS2022 strain is different from 6U7K and 7W6M. Animal pathogenicity test showed that GS2022 strain could cause severe clinical signs and the high level of virus shedding in 7-day-old piglets. But recovery of diarrhea after 5 days, and no pathological damage to important organs. Further study on 3-day-old piglets also indicated GS2022 strain have pathogenicity. In this study no piglets died, which make it possible for that GS2022 strain become a candidate vaccine. These results are helpful to understand the epidemiology, molecular characteristics, evolution, and antigenicity of PEDV circulating in China. It also provides reference for designing effective vaccines against PEDV.

Highly pathogenic avian influenza （HPAI） subtype H5Nx viruses have spread globally and are a major concern for poultry,wild birds,mammals,and even humans （de Vries et al.2015;Zeng et al.2022）.The hemagglutinin （HA）genes of H5 subtype viruses have evolved into multiple clades and some of these clades have been further divided into subclades （Cui et al.2022）.Clade 2.3.4.4H5N8 HPAI viruses （HPAIVs） have caused several waves of disease outbreaks in wild birds and domestic poultry（Wang et al.2022）.

Introduction:Porcine reproductive and respiratory syndrome virus (PRRSV) remains one of the most threatening pathogens of swine. The nucleocapsid (N) protein is the major structural protein of the virus and has been used as a PRRSV diagnostic antigen due to its high level of inherent immunogenicity.Methods:The recombinant PRRSV N protein was generated by the prokaryotic expressing system and used to immunized mice. Monoclonal antibodies against PRRSV were produced and validated by western blot analysis and indirect immunofluorescence analysis. In this study, the linear epitope of a specific monoclonal antibody mAb (N06) was subsequently identified by enzyme-linked immunosorbent assays (ELISA) using the synthesized overlapping peptides as antigens.Results:According to the results of western blot analysis and indirect immunofluorescence analysis, mAb (N06) was capable of recognizing the native form as well as the denatured form of PRRSV N protein. The results of ELISA showed that mAb N06 recognized the epitope NRKKNPEKPHFPLATE, which was consistent with BCPREDS predictions of antigenicity.Conclusion:All the data suggested that the mAb (N06) can be used as diagnostic reagents for PRRSV detection, while the recognized linear epitope can be useful in epitope-based vaccines development, which is helpful for the control of local PRRSV infections in swine.

A 2-year surveillance study of influenza A viruses in migratory birds was conducted to understand the subsequent risk during the migratory seasons in Dandong Yalu River Estuary Coastal Wetland National Nature Reserve, Liaoning Province, China, a major stopover site on the East Asian-Australasian flyway. Overall, we isolated 27 influenza A viruses with multiple subtypes, including H3N8 (n = 2), H4N6 (n = 2), H4N7 (n = 2), H7N4 (n = 9), H7N7 (n = 1), H10N7 (n = 7), and H13N6 (n = 4). Particularly, a novel reassortant influenza A(H7N4) virus was first identified in a woman and her backyard poultry flock in Jiangsu Province, China, posing a serious threat to public health. Here, we describe the genetic characterization and pathogenicity of the nine influenza A(H7N4) isolates. Phylogenetic analysis indicated that complex viral gene flow occurred among Asian countries. We also demonstrated a similar evolutionary trajectory of the surface genes of the A(H7N4) isolates and Jiangsu human-related A(H7N4) viruses. Our A(H7N4) isolates exhibited differing degrees of virulence in mice, suggesting a potential risk to other mammalian species, including humans. We revealed multiple mutations that might affect viral virulence in mice. Our report highlights the importance and need for the long-term surveillance of avian influenza virus in migratory birds combined with domestic poultry surveillance along migratory routes and flyways and, thereby, the development of measures to manage potential health threats. IMPORTANCE The H7 subtype avian influenza viruses, such as H7N2, H7N3, H7N4, H7N7, and H7N9, were documented as being capable of infecting humans, and the H7 subtype low pathogenicity avian influenza viruses are capable of mutating into highly pathogenic avian influenza; therefore, they pose a serious threat to public health. Here, we investigated the evolutionary history, molecular characteristics, and pathogenicity of shorebird-origin influenza A(H7N4) viruses, showing a similar evolutionary trajectory with Jiangsu human A(H7N4) viruses in HA and NA genes. Moreover, our isolates exhibited variable virulence (including moderate virulence) in mice, suggesting a potential risk to other mammalian species, including humans.

H5N8 and H5N1 highly pathogenic avian influenza viruses (AIVs) of clade 2.3.4.4b were isolated from dead migratory birds and fecal samples collected in Tibet, China, in May 2021. Phylogenetic analyses showed that the viruses isolated in this study may have spread from wintering or stopover grounds of migratory birds in South Asia. We monitored two disparate clade 2.3.4.4b H5Nx viruses in migratory birds in Tibet during their breeding season. The data revealed that breeding grounds may exhibit a potential pooling effect among avian influenza viruses in different migratory populations. IMPORTANCE In this study, 15 H5N8 and two H5N1 highly pathogenic avian influenza viruses of clade 2.3.4.4b were isolated from dead migratory birds and fecal samples in Tibet, China. Isolates of H5N1 virus of clade 2.3.4.4b have been rarely reported in China. Our findings highlight that breeding grounds may exhibit a potential pooling effect among avian influenza viruses (AIVs) in different migratory populations. In addition to intensification of the surveillance of AIVs in migratory birds in Tibet, China, international cooperation should be strengthened.

Canine distemper (CD) caused by canine distemper virus (CDV) is one of the major infectious diseases in minks, bringing serious economic losses to the mink breeding industry. By an integrated analysis of microRNA (miRNA)-messenger RNA (mRNA), the present study analyzed the changes in the mink transcriptome upon CDV infection in mink lung epithelial cells (Mv. l. Lu cells) for the first time. A total of 4,734 differentially expressed mRNAs (2,691 upregulated and 2,043 downregulated) with |log2(FoldChange) |>1 and P-adj<0.05 and 181 differentially expressed miRNAs (152 upregulated and 29 downregulated) with |log2(FoldChange) |>2 and P-adj<0.05 were identified. Gene Ontology (GO) enrichment indicated that differentially expressed genes (DEGs) were associated with various biological processes and molecular function, such as response to stimulus, cell communication, signaling, cytokine activity, transmembrane signaling receptor activity and signaling receptor activity. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis of the combination of miRNA and mRNA was done for immune and inflammatory responses, such as Janus kinase (JAK)-signal transducer and activator (STAT) signaling pathway and nuclear factor (NF)-kappa B signaling pathway. The enrichment analysis of target mRNA of differentially expressed miRNA revealed that mir-140-5p and mir-378-12 targeted corresponding genes to regulate NF-kappa B signaling pathway. JAK-STAT signaling pathway could be modulated by mir-425-2, mir-139-4, mir-140-6, mir-145-3, mir-140-5p and mir-204-2. This study compared the influence of miRNA-mRNA expression in Mv. l. Lu cells before and after CDV infection by integrated analysis of miRNA-mRNA and analyzed the complex network interaction between virus and host cells. The results can help understand the molecular mechanism of the natural immune response induced by CDV infection in host cells.

Highly pathogenic influenza A(H5N8) viruses have caused several worldwide outbreaks in birds and are able cross the species barrier to infect humans, posing a substantial threat to public health. After the first detection of H5N8 viruses in deceased swans in Inner Mongolia, we performed early warning and active monitoring along swan migration routes in central China. We isolated and sequenced 42 avian influenza viruses, including 40 H5N8 viruses, 1 H5N2 virus, and 1 H9N2 virus, in central China. Our H5N8 viruses isolated in swan stopover sites and wintering grounds showed high nucleotide homologies in the whole genome, revealing a common evolutionary source. Phylogenetic analysis revealed that the H5 viruses of clade 2.3.4.4b prevalent in 2020 have further diverged into two sub-clades: b1 and b2. The phylogeographic analysis also showed that the viruses of sub-clade b2 most likely originated from poultry in Russia. Notably, whooper swans were found to be responsible for the introduction of sub-clade b2 viruses in central China; whooper and tundra swans play a role in viral spread in the Yellow River Basin and the Yangtze River Basin, respectively. Our findings highlight swans as an indicator species for transborder spreading and monitoring of the H5N8 virus.

H5N8亚型高致病性禽流感病毒(highly pathogenic avian influenza virus,HPAIV)随候鸟的迁徙活动及商业贸易活动现已蔓延至亚洲、欧洲、非洲、美洲等国家和地区.2014-2015和2016-2019年H5N8亚型HPAIV已引发两波全球疫情,现正经历第三波疫情,导致家禽及野生鸟类大量死亡,造成严重的经济损失.已有研究发现,病毒基因位点突变能使其对犬、鼠、水貂等哺乳动物毒力增强,值得关注的是2021年2月俄罗斯首次报道人感染H5N8病毒事件,具有重要的公共卫生意义.本文针对在全球出现的家禽及野鸟H5N8亚型HPAIV疫情及流行情况进行综述,探讨其来源以及危害,建议加强野生鸟类特别是迁徙候鸟禽流感病毒的主动监测,早发现、早预警,最大程度减少禽流感疫情带来的经济损失及对人类健康带来的威胁.

During October 2020, we identified 13 highly pathogenic avian influenza A(H5N8) clade 2.3.4.4b viruses from wild ducks in Ningxia, China. These viruses were genetically related to H5N8 viruses circulating mainly in poultry in Europe during early 2020. We also determined movements of H5N8 virus‒infected wild ducks and evidence for spreading of viruses.

In October 2020, highly pathogenic avian influenza A(H5N8) viruses were detected in 2 dead swans in Inner Mongolia, China. Genetic analysis showed that the H5N8 isolates belong to clade 2.3.4.4b and that the isolates cluster with the H5N8 viruses isolated in Eurasia in the fall of 2020.