First detection of ungulate tetraparvovirus 1 (bovine hokovirus 1) in domestic yaks in northwestern China.

We describe the discovery and phylogenetic analysis of ungulate tetraparvovirus 1 (also referred to as bovine hokovirus 1, B-PARV4, or partetravirus) in domestic yaks (Bos grunniens) in northwestern China. The yak B-PARV4 genome was detected in yak blood samples by PCR, using B-PARV4 primers corresponding to conserved regions. Twenty-two of 370 samples were positive for a B-PARV4-related genome sequence, indicating an overall prevalence of 5.95 %. The prevalence in Qinghai Province (13/195, 6.67 %) and Gansu Province (9/175, 5.14 %) was similar, but it varied significantly between yaks ≤ 1 year old (15/177, 8.47 %) and yaks > 1 year old (7/193, 3.6 %) (p < 0.05). An alignment of the nearly full-length genome sequences of all 22 strains identified six different genomic sequences. A phylogenetic analysis revealed 99.0-99.7 % sequence identity between these six genomes and all known B-PARV4 genomes, excluding JF504698 (only 88.6 % identity), which represents another genotype. This is the first discovery of B-PARV4-related viruses in domestic yaks.