Isolation and identification of a novel goose astrovirus 2 and phylogenetic tree analysis

Goose astrovirus type 2 (GAstV-2) has recently emerged as a causative agent of fatal gout in goslings, causing significant economic losses to the waterfowl industry. This study aimed to isolate and characterize a novel GAstV-2 strain to understand its genetic evolutionary characteristics.A virus strain was isolated from clinical samples of diseased geese collected from a farm in Taizhou, Jiangsu province, and the virus was isolated by inoculating chicken liver cancer cells. The virus was identified by electron microscopy and RT-PCR. The complete genome was sequenced and analyzed using bioinformatic tools for phylogenetic relationship and genetic variation.A novel GAstV-2 strain, designated as GAstV/Goose/China/TZ04/2025, was successfully isolated. Typical astrovirus-like particles were observed under an electron microscope. The complete genome was determined to be 7018 in length. Phylogenetic analysis based on the complete genome and ORF2 gene revealed that the isolate clustered within the GAstV-2 clade but formed a distinct branch. It shared 97.55% - 99.86% nucleotide identity with other known GAstV-2 strains. Notably, several unique amino acid substitutions were identified in the capsid protein.This is the first report on the isolation and genomic characterization of a novel GAstV-2 variant. The findings expand our knowledge of the genetic diversity of GAstV-2 and provide valuable information for developing diagnostic tools and vaccines against this virus.