# First National Prevalence in Italian Horse Population and Phylogenesis Highlight a Fourth Sub-Type Candidate of Equine Hepacivirus

## TL;DR

This study reports the first national prevalence of equine hepacivirus in Italy and suggests the possible existence of a fourth sub-type.

## Contribution

The study identifies a potential fourth sub-type of equine hepacivirus through phylogenetic analysis in the Italian horse population.

## Key findings

- The national prevalence of EqHV in Italy is 4.27% with no significant differences among production categories or regions.
- Phylogenetic analysis suggests the presence of a possible fourth EqHV sub-type in Italy.
- Mutations in the NS3 protein may affect its binding affinity to viral RNA.

## Abstract

Equine hepacivirus (EqHV, Flaviviridae, hepacivirus) is a small, enveloped RNA virus generally causing sub-clinical hepatitis with occasional fatalities. EqHV is reported in equids worldwide, but for Italy data are limited. To address this, a survey study was set up to estimate prevalence at a national level and among different production categories (equestrian; competition; work and meat; reproduction) and national macro-regions (North, Central, South, and Islands). Data obtained testing 1801 horse serum samples by Real-Time RT PCR were compared within the categories and regions. The NS3 fragment of the PCR-positive samples was sequenced by Sanger protocol for phylogenetic and mutational analysis. The tertiary structure of the NS3 protein was also assessed. The estimated national prevalence was 4.27% [1.97–6.59, 95% CI] and no statistical differences were detected among production categories and macro-regions. The phylogenesis confirmed the distribution in Italy of the three known EqHV subtypes, also suggesting a possible fourth sub-type that, however, requires further confirmation. Mutational profiles that could also affect the NS3 binding affinity to the viral RNA were detected. The present paper demonstrates that EqHV should be included in diagnostic protocols when investigating causes of hepatitis, and in quality control protocols for blood derived products due to its parental transmission.