Genotypic analysis of a localised hotspot of Pestivirus A (BVDV-1) infections in Northern Ireland.

BACKGROUND: Bovine viral diarrhoea (BVD) is caused by Pestivirus A and Pestivirus B. Northern Ireland (NI) embarked on a compulsory BVD eradication scheme in 2016, which continues to this day, so an understanding of the composition of the pestivirus genotypes in the cattle population of NI is required. METHODS: This molecular epidemiology study employed 5' untranslated region (5'UTR) genetic sequencing to examine the pestivirus genotypes circulating in samples taken from a hotspot of BVD outbreaks in the Enniskillen area in 2019. RESULTS: Bovine viral diarrhoea virus (BVDV)-1e (Pestivirus A) was detected for the first time in Northern Ireland, and at a high frequency, in an infection hotspot in Enniskillen in 2019. There was no evidence of infection with BVDV-2 (Pestivirus B), Border disease virus (pestivirus D) or HoBi-like virus/BVDV-3 (pestivirus H). LIMITATIONS: Only 5'UTR sequencing was used, so supplementary sequencing, along with phylogenetic trees that include all BVDV-1 genotype reference strains, would improve accuracy. Examination of farm locations and animal movement/trade is also required. CONCLUSIONS: Genotype BVDV-1e was found for the first time in Northern Ireland, indicating an increase in the genetic diversity of BVDV-1, which could have implications for vaccine design and highlights the need for continued pestivirus genotypic surveillance.

Pestivirus apparent prevalence in sheep and goats in Northern Ireland: A serological survey.

BACKGROUND: Bovine viral diarrhoea virus (BVDV) and border disease virus (BDV) can cause significant health problems in ruminants and economic impacts for farmers. The aim of this study was to evaluate pestivirus exposure in Northern Ireland sheep and goat flocks, and to compare findings with a previous study from the region. METHODS: Up to 20 animals were sampled from 188 sheep and 9 goat flocks (n = 3,418 animals; 3,372 sheep and 46 goats) for pestivirus antibodies. Differentiation of the causative agent in positive samples was inferred using serum neutralisation. Abortion samples from 177 ovine cases were tested by BVDV reverse-transcription polymerase chain reaction and antigen ELISA. RESULTS: Apparent animal and flock (one antibody positive animal within a flock) prevalence was 1.7% and 17.3%, respectively, a statistically significant drop in apparent prevalence since a survey in 1999. 52.6% of samples testing positive had higher antibody titres to BVDV than to BDV. Of the ovine abortion samples, only one positive foetal fluid sample was detected by ELISA. CONCLUSION: The present study found that, since 1999, there has been a decrease in apparent animal and flock prevalence of 3.7 and 12.8 percentage points respectively, suggesting pestivirus prevalence has decreased across Northern Ireland between 1999 and 2018.