Submitted to: Journal of Virology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/27/2016
Publication Date: 9/18/2016
Publication URL: http://handle.nal.usda.gov/10113/5510074
Citation: Weber, M.N., Bauermann, F.V., Canal, C.W., Bayles, D.O., Neill, J.D., Ridpath, J.F. 2016. Temporal dynamics of ‘HoBi’-like pestivirus quasispecies in persistently infected calves generated under experimental conditions. Journal of Virology. 227(2017):23-33: doi: 10.1016/j.virusres.2016.09.018.

Interpretive Summary: The disease syndromes known collectively as bovine viral diarrhea (BVD) cause major economic losses for beef and dairy producers worldwide. BVD is caused by three difference kinds of virus bovine viral diarrhea virus type 1 (BVDV1), bovine viral diarrhea virus type 2 (BVDV2) and the recently recognized HoBi-like virus (HoBi-like). These three viruses can cause acute infections, in which the virus is eliminated in about 14 days, and persistent infections, in which the virus is never eliminated resulting in a life long infection. While persistently infected (PI) animals are infected for life, it is not known if the virus changes (mutates) over time. In this study, cattle persistently infected with HoBi-like viral strains were samples over a three month period. It was found that the viruses that they carry do change but that the changes tend to be limited to certain genes. This indicates that the rate and type of mutation that occurs in the virus during persistent infections is limited and controlled. It is theorized that this control is the result of the virus and host systems working together. The information generated in this study will be used to increase our understanding of how viruses avoid being eliminated by the immune system.

Technical Abstract: ‘HoBi’-like virus is an atypical group within the Pestivirus genus that is implicated in economic losses for cattle producers due to both acute and persistent infections. Pestivirus strains exist as quasispecies (swarms of individual viruses) in infected animals and the viral populations making up the quasispecies differ widely in size and diversity in each animal. In the present study the viral quasispecies circulating in persistently infected (PI) calves, generated and maintained under experimental conditions using two different ‘HoBi’-like strains, was observed over time. An increase in genetic variability and the development of certain mutations was observed over time. Mutations observed included the loss of a putative N-linked glycosylation site in the E2 region and the change of specific residues in E1/E2. It is hypothesized that these changes may be the results on continued adaption of the pestivirus to individual hosts. This is the first study characterizing variation in the viral swarms of animals persistently infected with HoBi-like viruses over time. Studies of the shifts in PI viral swarms will contribute to our understanding of the host and viral mechanisms that function in the maintenance of Pestivirus persistent infections.