First detection and genetic characterization of a novel kirkovirus from a dead thoroughbred mare in northern Xinjiang, China, in 2018

Background In May 2018, a 8 year old thoroughbred mare died at an equestrian club in Changji, Xinjiang, China. The horse had been imported from the United States in 2013. She became pregnant in December 2016 but, after foaling, gradually lost weight and died in May 2018. This study aim to identify the pathogen, who cause of horse death, using virome. Results We have identified an Equ1-like virus from the fecal virome of a dead thoroughbred mare in China. Full genomic sequencing and phylogenetic analysis of the virus, tentatively named kirkovirus Cj-7-7, showed that it was closely related to kirkovirus Equ1 and clustered together with po-circo-like viruses 21, 22, 41, and 51, suggesting that it should be assigned to the proposed family Kirkoviridae. An epidemiological investigation showed that kirkovirus Cj-7-7 circulates in horses of northern Xinjiang and may specifically infect intestinal cells. Conclusions Our findings demonstrate the genetic diversity and geographic distribution of Kirkoviruses, and the prevalence of Kirkovirus Cj-7-7 in Xinjiang, China.