First detection of the occurrence and study of the genetic diversity of novel putative kirkoviruses in donkey in China

The first representative of a seemingly novel virus family has been found during the metagenomic examination of a diseased and dead horse in the USA [Li et al. in J Gen Virol 96:2721-2733, 2015]. These authors have suggested the need for the establishment of a new family with the tentative name Kirkoviridae; however, the suggested name is not official yet. Soon after the discovery, similar, relatively large CRESS-DNA viruses have been detected in various animals in China and elsewhere. Besides the two main genes (rep and cap), characteristic for members of the family Circoviridae, the tentative kirkoviruses have considerably larger genomes of approximately 4000 nucleotides. Accordingly, these viruses possess three four additional ORFs coding for proteins of unknown function. This has been described previously. In the present manuscript, the authors report the sequence of kirkovirus-like viruses, detected by PCR in donkey excretes in China. From 73 samples, 8 were found positive. From three of these newly detected viruses, the full genomic sequence was determined, whereas from the other five only one gene, namely the replication-associated (Rep) protein was sequenced.