Genetic characterization and isolation of feline astrovirus in domestic cats in Guangxi, China.

Feline astrovirus (FAstV), as an intestinal pathogen, has been widely detected worldwide, but little is known about its genetic evolutionary diversity and isolation. This study presents the comprehensive molecular epidemiological investigation of FAstV in Guangxi, China. Screening 775 feline intestinal samples revealed an FAstV prevalence of 4.25 % (33/775), with 39.4 % (13/33) of positive cases co-infected with six other major feline enteric viruses. Notably, FAstV-feline panleukopenia virus (FPV) co-infection emerged as the predominant viral combination (27.27 %, 9/33), suggesting potential synergistic pathogenesis in feline gastroenteritis cases. Phylogenetic analysis of 13 ORF2 genes and 2 complete genomes identified three distinct FAstV genogroups (G1-G3) with significant amino acid divergence (0.445-0.765 p-distance), supporting their classification as separate genotypes. Additionally, we successfully isolated a novel FAstV strain (GXNNF10-2024) in trypsin-supplemented feline kidney-derived FK81 cell cultures, which exhibited characteristic cytopathic effects (CPEs) and was confirmed by RT-PCR and immunofluorescence. These findings significantly enhance our understanding of FAstV genetic diversity, provide essential tools for viral isolation, and establish a foundation for developing diagnostic and control strategies against this emerging feline enteric pathogen.