Molecular characterization of the Gyrovirus galga 1 strain detected in various zoo animals: the first report from China

Abstract

Since 2011, the Gyrovirus galga 1 (GyVg1, previously recognized as avian gyrovirus 2) strain has extensively been detected worldwide. The virus has been identified in several species, including chickens, humans, domestic cats, and snakes, especially in China. Therefore, in this study, the presence of GyVg1 was investigated in various zoo animals to determine whether it exists in various species in Nanyang, China. A total of 63 whole blood samples (1 sample from each animal) from 24 animal species were collected from the Nanyang Zoo. Eight different GyVg1 strains were identified in eight types of animals using polymerase chain reaction, and the full genome of each strain was sequenced. The whole genome of four GyVg1 strains, namely, HN2019-H1, HN2019-T1, HN2019-SD1, and HN2019-L1 identified in hippopotamus (Hippopotamus amphibius), tiger (Panthera tigris), sika deer (Cervus nippon), and lion (Panthera leo), respectively, comprised 2375 nucleotides (nt). The whole genome of the other strains, namely, HN2019-E1, HN2019-S1, HN2019-PF1, and HN2019-P1 identified in egret (Egretta garzetta), silver pheasant (Lophura nycthemera), peafowl (Pavonini), and common pheasants (Phasianus colchicus), respectively, comprised 2376 nt. Subsequently, a phylogenetic tree was constructed based on the 8 whole-genome sequence strains and 29 reference strains. These 37 strains were grouped into two major branches, group A and group B, and the 8 strains identified in this study were placed in group A. An analysis of the amino acids encoded by three open reading frames revealed some mutation sites unique to these eight strains. The substitution occurred at site 110 of viral protein 2 of HN2019-PF1, which is located in the highly conserved phosphatase motif WX7HX3CXCX5H (95-115aa). Recombination analysis revealed that, all these viral sequences were obtained as a result of recombination among the three GyVg1 strains (JL1511 and GS1512 from chickens and 17CC0810 from cat) from China and two strains (G17 from ferret of Hungary and RS-BR-15-2S from chicken of Brazil) from other countries. These findings indicate the complex evolution of GyVg1. Nevertheless, its transmission across the hosts is worth exploring.

Keywords: Amino acid substitution; Avian gyrovirus 2; Gyrovirus galga 1; Phylogenetic analysis; Recombination analysis.