Location: Virus and Prion ResearchTitle: Porcine reproductive and respiratory disease virus: evolution and recombination yields distinct ORF5 RFLP 1-7-4 viruses with individual pathogenicity
|VAN GEELEN, ALBERT - Orise Fellow|
|DAS, PHANI - Orise Fellow|
|MONTIEL, NESTOR - Orise Fellow|
|KULSHRESHTHA, VIKAS - Orise Fellow|
|BUCKLEY, ALEXANDRA - Orise Fellow|
Submitted to: Virology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/2/2017
Publication Date: 1/1/2018
Citation: van Geelen, A.G.M., Anderson, T.K., Lager, K.M., Das, P.B., Otis, N.J., Montiel, N.A., Miller, L.C., Kulshreshtha, V., Buckley, A.C., Brockmeier, S.L., Zhang, J., Gauger, P.C., Harmon, K.M., Faaberg, K.S. 2018. Porcine reproductive and respiratory disease virus: evolution and recombination yields distinct ORF5 RFLP 1-7-4 viruses with individual pathogenicity. Virology. 513:168-179.
Interpretive Summary: Porcine reproductive and respiratory syndrome virus (PRRSV) represents the most economically important infectious threat to the productivity and health of swine in the United States today. The virus has defied control due to its ability to evade the host immune system: a trait driven by extraordinary genetic variability that enables it to change and adapt to the pig's immune response. There are few comprehensive whole-genome studies that describe viral diversity, and there are no studies documenting how this diversity across the entire genome impacts how the virus causes disease. In this study, the genomic sequence of seventeen contemporary clinical disease PRRSV isolates considered similar based on one type of genetic test were derived, representative isolates were selected, and were used in a comparative study evaluating the disease caused by each isolate. These data demonstrated that the standard genetic test originally used to determine PRRSV genetic diversity, and frequently used to predict if a specific virus will cause severe disease, can be inaccurate.
Technical Abstract: Recent cases of porcine reproductive and respiratory syndrome virus (PRRSV) infection in United States swineherds have been associated with high mortality in piglets and severe morbidity in sows. Analysis of the ORF5 gene from such clinical cases revealed a unique restriction fragment polymorphism (RFLP) of 1-7-4. The genome diversity of seventeen of these viruses (81.4% to 99.8% identical; collected 2013-2015) and the pathogenicity of 4 representative viruses were compared to that of SDSU73, a known moderately virulent strain. Recombination analyses revealed genomic breakpoints in structural and nonstructural regions of the genomes with evidence for recombination events between lineages. Pathogenicity varied between the strains and the patterns were not consistent. IA/2014/NADC34, IA/2013/ISU-1 and IN/2014/ISU-5 caused more severe disease, and IA/2014/ISU-2 did not cause pyrexia and had little effect on growth. ORF5 RFLP genotyping was ineffectual in providing insight into strain pathogenicity and that other parameters of virulence remain to be identified.