# No evidence of BoHV-1 exposure and low levels of pestivirus exposure in sera from 116 opportunistically sampled wild deer in Northern Ireland

## TL;DR

This study found no evidence of BoHV-1 exposure and very low pestivirus exposure in wild deer in Northern Ireland.

## Contribution

The first report of pestivirus antibodies in sika deer in Europe.

## Key findings

- No antibodies against BoHV-1 were detected in any of the 116 deer samples.
- Antibodies against pestivirus were found in 2.6% of samples, all from sika deer.
- Deer are unlikely to be significant wildlife reservoirs for these viruses based on the results.

## Abstract

Bovine Viral Diarrhoea Virus (BVDV), Border Disease Virus (BDV), and Bovine Herpesvirus-1 (BoHV-1, the cause of Infectious Bovine Rhinotracheitis, IBR), are economically important endemic viruses in ruminant livestock in the United Kingdom and Ireland. Deer could undermine control efforts in livestock by contributing to virus transmission and maintenance, but information on the presence of these viruses in the wild deer population is lacking. Blood samples from wild fallow and sika deer culled in Northern Ireland were collected opportunistically in the 2022–23 hunting season and tested using enzyme-linked immunosorbent assay (ELISA) for the presence of antibodies to these viruses (n = 116). No antibodies against BoHV-1 were detected. Antibodies against pestivirus were detected in three samples (2.6%), all from sika deer, and constitute the first report in this species in Europe. Virus strain differentiation by virus neutralization test (VNT) was inconclusive. Results therefore indicate no evidence of exposure to BoHV-1 and very low levels of pestivirus exposure in these deer populations. Based on these results there are currently no grounds to implicate deer as significant wildlife reservoirs of these viruses.