First detection and genetic characterization of donkey-like kirkovirus in diarrhoeal piglets in Xinjiang, China

Kirkovirus (kirV), a seemingly novel virus family, has been found in horses and donkey. The objectives of the study intend to investigate the presence of the virus in swine. In this study, donkey-like kirkovirus (kirV) was detected in anal swabs of piglets with diarrhoea and the positive rate was found to be 100% (149/149), but this virus was detected in only one of 261 clinically healthy piglets, which suggested a strong relationship between the kirV and the diarrhoeal disease. We obtained the whole-genome sequences of three kirVs (named Cj-D5, Cj-D32 and Cj-D43), with length of 3750 nt and sharing 99.9% nucleotide (nt)-identity with donkey kirVs. Furthermore, three viruses shared 88.5%–100%, and 23%–51% of the Rep protein sequence identity with available reference strains of the families Kirkoviridae , Circoviridae , respectively. Moreover, like horse and donkey kirVs, RCR domain and P-loop NTPase domains of Rep protein and nonanucleotide motif (CAATATTAC), of the three viruses, were similar to those of Circoviruses and Cycloviruses . Phylogenetic analysis showed that these viruses could be potentially grouped together with members in the proposed family Kirkoviridae . This is the first report to describe that kirV can circulate in piglets with diarrhoea and future studies are needed to determine the pathogenesis of this virus.