Impact assessment of genotype diversity on vaccine efficacy as control strategy for BVDV in beef herds in Argentina

MARIA SOL PEREZ-AGUIRREBURUALDE; PECORA ANDREA; DUS SANTOS MARIA JOSE; LEON EMILIO; PEREZ ANDRES

Congreso; International Symposium on Veterinary Epidemiology and Economics?; 2018

Bovine Viral Diarrhea Virus (BVDV) is endemic in most regions around the world and has a detrimental effect on herds´ performance. In Argentina, it is highly prevalent and the most widely used control tool has been vaccination using inactivated vaccines. Until now, most of these vaccines only include historical reference strains and have not been updated since being registered. The aim of this study was to determine what the real costs and benefits are of using monovalent or bivalent commercial BVDV vaccines in Argentina considering the true genotype diversity. A stochastic model on herd level was used to model the prevalence and economic consequences. The genotype diversity was obtained by analyzing xx BVDV isolated from samples collected in Buenos Aires province. Phylogenetic and antigenic analysis were performed. The isolates were genotyped based on the 5 untranslated region (5 ´UTR) and the E2 gene (which codes for the major envelope glycoprotein). In both phylogenetic trees, isolates were classified as BVDV 1a = 13.3%, BVDV 1b = 76.67%, BVDV 2a 6.6%, and BVDV 2b 3.33%. Isolates were further characterized by cross-neutralization tests using guinea pig monospecific antisera, to build an antigenic similarity matrix between genotypes. Based on these results, six potential scenarios were simulated, based on the antigenic similarity between the vaccine strain and the challenge field strain. There were just two scenarios were the cost benefit analysis resulted beneficial. Further, we compare the relative effectiveness obtained with other strategies (detection of PI; modified live vaccines) reported in the literature. These findings demonstrated indisputable the impact of the antigenic diversity among Argentinean BVDV isolates in the effectiveness of commercial vaccines at herd level, suggesting the need to incorporate genotypes that represent local diversity in commercial formulations.