Description of an Equine Hepacivirus Cluster in a Horse Stable in Italy

Equine hepacivirus (EqHV), also known as Hepacivirus A, represents the most closely related genetic homologue of human hepatitis C virus (HCV). Although detected worldwide, limited information on the clinical features of this infection is available and on the mechanisms by which EqHV is transmitted. In this study, we describe a spread of infection of EqHV that occurred in a small stable of horses in southern Italy. The RNA of EqHV was detected in 6/13 (46.2%) sera of the horses introduced into the herd, at different times, over a period of approximately one year. Based on the sequencing analyses of genomic portions located in the NS5B, 5 ' UTR, and NS3 genes, the viruses detected in the animals were genetically highly related (100% nt identity) to each other. The nearly full-length genome of the virus identified from two horses was generated. For one animal with a profile of chronic infection, the genome sequence was determined with a 7-month interval, revealing 26nt changes resulting in 11 nonsynonymous intrahost nucleotide variations. Overall, based on the epidemiological information, we support the hypothesis that horizontal transmission occurred in the herd.