Pseudorabies virus (PRV) has received widespread attention for its potential health effects on humans, wildlife, domestic animals, and livestock. In this review, we focus on PRV dynamics in wildlife, given the importance of wild-origin PRV transmission to domestic and farm animals. Wild boars, pigs, and raccoons can serve as reservoirs of PRV, with viral transmission to domestic livestock occurring via several routes, such as wild herd exposure, contaminated meat consumption, and insect vector transmission. Many endangered feline and canine species can be infected with PRV, with acute disease and death within 48 h. The first confirmed human case of PRV infection in mainland China was reported in 2017. Thus, PRV exhibits potentially dangerous cross-host transmission, which is likely associated with inappropriate vaccination, poor awareness, and insufficient biosecurity. Currently, no vaccine provides full protection against PRV in all animals. Here, we summarize the epidemiology and pathogenesis of PRV infection in wild, domestic, and farmed animals, which may facilitate the design of novel therapeutics and strategies for controlling PRV infection and improving wildlife protection in China.

Porcine transmissible gastroenteritis virus (TGEV) is the major etiological agent of viral enteritis and severe diarrhea in suckling piglets. In China, TGEV has caused great economic losses, but its role in epidemic diarrhea is unclear. This study aims to reveal the etiological role of TGEV in piglet diarrhea via molecular characterization and phylogenetic analysis. A TGEV-HX strain was isolated from China, and its complete genome was amplified, cloned, and sequenced. Sequence analysis indicated that it was conserved in the 5′ and 3′-non-translated regions, and there were no insertions or deletions in nonstructural genes, such as ORF1a, ORF1b, ORF3a, ORF3b, and ORF7, as well as in genes encoding structural proteins, such as the envelope (E), membrane (M), and nucleoprotein (N) proteins. Furthermore, the phylogenetic analysis indicated that the TGEV-HX strain was more similar to the TGEV Purdue cluster than to the Miller cluster. The present study described the isolation and genetic characterization of a TGEV-HX strain. The detailed analysis of the genetic variation of TGEVs in China provides essential information for further understanding the evolution of TGEVs.

Introduction: The gastrointestinal tract and oral cavity of animal species harbor complex microbial communities, the composition of which is indicative of the behavior, co-evolution, diet, and immune system of the host.Methods: This study investigated the microbial composition in snakes from varying altitudinal ranges by assessing the fecal and oral bacterial communities in Protobothrops mucrosquamatus, Elaphe dione, and Gloydius angusticeps from Sichuan Province, China, using metagenomic sequencing.Results and discussion: It was revealed that Bacteroidetes, Proteobacteria, Firmicutes, and Fusobacteria were the core microbial phyla in fecal samples across all three species, while Proteobacteria, Bacteroidetes, Actinobacteria, and Firmicutes were the core microbial phyla in oral samples across all three species. Notably, the dominance of Armatimonadetes was documented for the first time in the feces of all three species. Comparative analysis of the microbiomes of the three species indicated distinct microbiological profiles between snakes living at low- and high-altitude regions. Furthermore, 12 to 17 and 22 to 31 bacterial pathogens were detected in the oral and fecal samples, respectively, suggesting that snakes may serve as a novel reservoir for emerging diseases. Overall, this study provides a comparative analysis of the fecal and oral microbiomes in three snake species. Future investigations are anticipated to further elucidate the influence of age, genetics, behavior, diet, environment, ecology, and evolution on the gut and oral microbial communities of snakes.

Budgerigar fledgling disease virus (BFDV) is the causative polyomavirus of budgerigar fledgling disease, an important avian immunosuppressive disease in budgerigars (Melopsittacus undulatus). In the current study, we explored the etiological role and molecular characteristics of BFDV. We identified a novel BFDV strain, designated as SC-YB19, belonging to a unique cluster with three other domestic strains (WF-GM01, SD18, and APV-P) and closely related to Polish isolates based on complete sequences. Sequence analysis showed that SC-YB19 had an 18-nucleotide (nt) deletion in the enhancer region, corresponding to the sequence position 164–181 nt, which differed significantly from all other BFDV strains. Based on sequence alignment, three unique nucleotide substitutions were found in VP4 (position 821), VP1 (position 2,383), and T-antigen (position 3,517) of SC-YB19, compared with SD18, WF-GM01, QDJM01, HBYM02, APV7, and BFDV1. Phylogenetic analyses based on complete sequences suggested that SC-YB19, along with the domestic WF-GM01, SD18, and APV-P strains, formed a single branch and were closely related to Polish, Japanese, and American isolates. These results demonstrate that BFDV genotype variations are co-circulating in China, thus providing important insight into BFDV evolution.

Since 2010, a variant of porcine epidemic diarrhea virus (PEDV) has re-emerged in several provinces of China, resulting in severe economic losses for the pork industry. Here, we isolated and identified a variant PEDV strain, SC-YB73, in Guangdong Province, China. The pathological observations of jejunum showed atrophy of villi and edema in the lamina propria. The sequence analysis of the viral genome identified a six-nucleotide insertion in the E gene, which has not previously been detected in PEDV strains. Furthermore, 50 nucleotide sites were unique in SC-YB73 compared with 27 other PEDV strains. The phylogenetic analysis based on the complete genome showed that SC-YB73 was clustered in variant subgroup GII-a, which is widely prevalent in the Chinese pig population. The recombination analysis suggested that SC-YB73 originated from the recombination of GDS47, US PEDV prototype-like strains TW/Yunlin550/2018, and COL/Cundinamarca/2014. In the present study, we isolated and genetically characterized a variant PEDV strain, thus providing essential information for the control of PED outbreaks in China.

Background: According to the differences of antigen and genetic composition, canine coronavirus (CCoV) consists of two genotypes, CCoV-I and CCoV-II. Since 2004, CCoVs with point mutations or deletions of NSPs are contributing to the changes in tropism and virulence in dogs. Results: In this study, we isolated a CCoV, designated HLJ-071, from a dead 5-week-old female Welsh Corgi with severe diarrhea and vomit. Sequence analysis suggested that HLJ-071 bearing a complete ORF3abc compared with classic CCoV isolates (1-71, K378 and S378). In addition, a variable region was located between S gene and ORF 3a gene, in which a deletion with 104 nts for HLJ-071 when compared with classic CCoV strains 1-71, S378 and K378. Phylogenetic analysis based on the S gene and complete sequences showed that HLJ-071 was closely related to FCoV II. Recombination analysis suggested that HLJ-071 originated from the recombination of FCoV 79-1683, FCoV DF2 and CCoV A76. Finally, according to cell tropism experiments, it suggested that HLJ-071 could replicate in canine macrophages/monocytes cells. Conclusion: The present study involved the isolation and genetic characterization of a variant CCoV strain and spike protein and ORF3abc of CCoV might play a key role in viral tropism, which could affect the replication in monocyte/macrophage cells. It will provide essential information for further understanding the evolution in China.