Genetic diversity and evolution of goose astrovirus in the east of China

Goose astrovirus (GAstV), an agent of fatal visceral gout in goslings, has been widely circulating in eastern China since 2017, but little is known about its genetic diversity and systematic evolution. In this study, we isolated and sequenced nine nearly full-length GAstV genomes and conducted comprehensive genetic diversity and evolutionary analysis and compared them with other reported GAstV sequences. Our results indicated that two genotypic species of GAstV were circulating in China, and GAstV-2 subgenotype II-c had arisen as the dominant genotype in Shandong province and across the whole country. Multiple alignments of GAstV amino acid sequences revealed several characteristic mutations in GAstV-2 II-c strains, as well as additional residues in the nine new isolates which varied over time. Phylogenetic analysis of three open reading frames demonstrated different evolutionary histories. Evidence of natural recombination was also detected in GAstV, with most of the recombination occurring in the GAstV-2 II-c subgenotype. Molecular adaptation analyses revealed that the evolution of GAstV was shaped by strong negative selection, although a number of amino acids, which potentially affect host infection and cell entry, were subjected to positive pressure. Overall, these findings improve our understanding of the epidemiology and evolution of GAstV and may help in the development of vaccines and diagnostics.

Automated summary

The study investigates the genetic diversity and evolution of Goose astrovirus (GAstV) in China. Two genotypic species of GAstV were found to be circulating, with GAstV-2 subgenotype II-c being the dominant genotype in Shandong province and the whole country. The study also identified characteristic mutations and residues in GAstV-2 II-c strains and detected evidence of natural recombination in GAstV. Molecular adaptation analyses revealed the influence of negative selection on GAstV evolution while observing positive pressure on amino acids potentially affecting host infection and cell entry. These findings provide valuable insights for the understanding and prevention of GAstV, and contribute to the development of vaccines and diagnostics.