Identification of equine hepacivirus infections in France: Facts and Physiopathological insights
Résumé
Hepatitis C virus (HCV) is one of the main causes of end stage liver diseases (cirrhosis and hepatocellular carcinoma) in humans. In vivo studies have been hampered by a lack of access to relevant animal models. Until recently, the genus Hepacivirus was comprised of seven HCV genotypes, plus GBV-B that infects New World monkeys. Within the past few years, new hepaciviruses were identified in dogs and horses (also called canine/equine or non-primate hepaciviruses), in Old World monkeys (Colobus guereza), as well as in rodents (Myodes glareolus and Rhabdomys pumilio) and bats. Yet, the data available regarding newly identified hepacivirus infections is still limited, including in horses. So far, few studies have reported PCR positive horses in different countries (USA, Scotland, Germany, Japan, Brazil and Hungary). The aim of our study was to determine the prevalence of active hepacivirus infections in horses. A RT-qPCR adapted from the test described by Burbello et al. was developed according to the AFNOR norm U47-600-2. We detected 69 positive horses out of 1229 screened with this assay (5,6%). Positive horse samples originated from all parts of France. The number of viral genomes circulating in the blood of hepacivirus-infected horses ranged from 1.15 x 104 to 2.8 x 109 copies/mL, with two third of the results above a threshold of 4.26 x 107 copies/mL. There was no evidence of concomitant hepatic inflammation in the sera, as tested by the levels of gamma-glutamyl transferase and glutamate deshydrogenase. A one-year follow-up study in 7 horses from the same stud farm showed that, from the time of detection, infection persisted up to 18 months. A phylogenetic analysis was performed based on the nucleotide sequences of the 5’-untranslated region of the genome, as well as of the genes encoding the nonstructural proteins 3 and 5B. The result of this analysis suggests that all positive horses identified in France are infected with equine hepacivirus variants distinct from those previously reported. The present study demonstrates for the first time the presence of a significant proportion of ongoing equine hepacivirus infections in the horse herds in France. Determining the consequences of persistent hepacivirus infections in horses warrants further investigation.
