Further Evidence for in Utero Transmission of Equine Hepacivirus to Foals

Abstract

(1) Background: Equine hepacivirus (EqHV), also referred to as non-primate hepacivirus (NPHV), infects horses—and dogs in some instances—and is closely related to hepatitis C virus (HCV) that has infected up to 3% of the world’s human population, causing an epidemic of liver cirrhosis and cancer. EqHV also chronically infects the liver of horses, but does not appear to cause serious liver damages. Previous studies have been looking to identify route(s) of EqHV transmission to and between horses. (2) Methods: In this retrospective study, we sought to evaluate the prevalence of vertical transmission taking place in utero with measuring by quantitative RT-PCR the amounts of EqHV genome in samples from 394 dead foals or fetuses, paired with the allantochorion whenever available. (3) Results: Detection of EqHV in three foals most likely resulted from a vertical transmission from the mares to the fetuses, consistent with the in utero transmission hypothesis. In support of this observation, the presence of EqHV genome was found for the first time in two of the allantochorions. (4) Conclusions: As seemingly benign viruses could turn deadly (e.g., Zika flavivirus) and EqHV happens to have infected a significant proportion of the world’s horse herds, EqHV infectious cycle should be further clarified.

Equine Hepacivirus: A Systematic Review and a Meta-Analysis of Serological and Biomolecular Prevalence and a Phylogenetic Update

“…To date, vertical transmission has been recorded in two single studies [ 27 , 28 ]. In the first study, 21 Thoroughbred mares were monitored before parturition and for 6 months post-partum.…”

“…In the other study, out of 394 dead foals or fetuses, 3 (0.76%) showed the presence of the EqHV genome. EqHV was also detected, for the first time, in two allantochorions: one of them had a 100% sequence homology with that identified in the mare’s serum [ 28 ]. This evidence suggests a clear vertical transmission route, even though the authors also hint that probably only variants of the virus could promote EqHV in utero transmission since, otherwise, the numbers of cases worldwide should be much higher than observed.…”

Expanded Diversity and Host Range of Bovine Hepacivirus—Genomic and Serological Evidence in Domestic and Wild Ruminant Species

“…Vertical transmission of HCV occurs in approximately 5% of infected mothers [ 46 ]. This route of virus transfer has also been described for EqHV [ 47 , 48 ] and is well known for other members of the Flaviviridae , such as bovine viral diarrhea virus (BVDV) [ 49 ]. Accordingly, it is reasonable to speculate that mother-to-fetus infection could play a role in BovHepV epidemiology.…”

An Equine Model for Vaccination against a Hepacivirus: Insights into Host Responses to E2 Recombinant Protein Vaccination and Subsequent Equine Hepacivirus Inoculation

“…The vaccine ponies showed an earlier median peak serum EqHV RNA load, followed by an earlier decrease in median serum RNA load below LLOQ. The natural routes of horizontal EqHV transmission remain unknown, with respiratory transmission and arthropod-borne transmission being considered as possibilities [ 34 , 35 , 36 ]. Lower serum EqHV RNA load and earlier serum RNA clearance in vaccinated animals may also result in decreased risk of transmission.…”