Insight into the Epidemiology and Evolutionary History of Novel Goose Astrovirus-Associated Gout in Goslings in Southern China

Abstract

A novel gout disease, characterized by visceral urate deposition with high-mortality, with outbreaks in goslings in China since 2016 was caused by a novel goose astrovirus (GoAstV) and resulted in serious economic loss. However, the epidemiology and variation of the GoAstV in goslings in southern China and its evolutionary history as well as the classification of the GoAstV are unclear. In the present study, systematic molecular epidemiology, and phylogenetic analyses of the GoAstV were conducted to address these issues. Our results showed that the GoAstV is widespread in goslings in southern China, and the genomes of six GoAstV strains were obtained. Two amino acid mutations (Y36H and E456D) were identified in capsid proteins in this study, which is the dominant antigen for the GoAstV. In addition, the GoAstV could be divided into two distinct clades, GoAstV-1 and GoAstV-2, and GoAstV-2 is responsible for gout outbreaks in goslings and could be classified into Avastrovirus 3 (AAstV-3), while GoAstV-1 belongs to Avastrovirus 1 (AAstV-1). Moreover, the emergence of GoAstV-2 in geese was estimated to have occurred in January 2010, approximately 12 years ago, while GoAstV-1 emerged earlier than GoAstV-2 and was estimated to have emerged in April 1985 based on Bayesian analysis. The mean evolutionary rate for the GoAstV was also calculated to be approximately 1.42 × 10^-3 nucleotide substitutions per site per year. In conclusion, this study provides insight into the epidemiology of the GoAstV in goslings in southern China and is helpful for understanding the origin and evolutionary history as well as the classification of the GoAstV in geese.

Keywords: GoAstV; evolutionary history; gout; molecular epidemiology.

Figure 1

Postmortem lesions and histopathologic changes of goslings presented with gout clinical signs. (A–C) Urate deposits in the joints and ureter, on the surface of livers, and swelling of the kidneys. (D) Swelling of glomeruli and necrosis of renal tubular epithelial cells, as well as inflammatory cell infiltration (arrow) in kidneys (H&E). (E) Necrosis of hepatocytes and inflammatory cell infiltration (star) in the liver (H&E). (F) Splenic lymphocyte necrosis and hyperplasia (H&E). (G–I) Normal kidney, liver and spleen HE sections of an uninfected gosling (H&E).

Figure 2

Phylogenetic analysis of the GoAstV with other astroviruses constructed based on the complete genome. The tree was constructed with the neighbor-joining method with 1000 bootstrap replicates in MEGA 5.0 after multiple sequence alignments by MAFFT. The strains shown in blue with solid blue circles were identified in this study, and proposed species yet to be recognized are designated with asterisks.

Figure 3

Phylogenetic analysis of the GoAstV with other astroviruses constructed based on the RdRp and Cap genes. (A) Phylogenetic tree of astroviruses constructed by using the RdRp gene (1551 bp) and (B) phylogenetic tree of astroviruses constructed by using the Cap gene (2115 bp). The strains shown in blue with solid blue circles were identified in this study, and proposed species yet to be recognized are designated with asterisks.

Figure 4

Bayesian maximum clade credibility (MCC) phylogenetic tree constructed in BEAST 1.8.3 using the Markov chain Monte Carlo (MCMC) method based on the RdRp gene. The mean TMRCA was estimated for each key node, and the high posterior probability values are shown for each key node and provide an assessment of the degree of support for the node on the tree. The strains shown in blue color were identified in this study, and proposed species yet to be recognized are designated with asterisks.