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Research Project: Intervention Strategies to Control Endemic and New and Emerging Viral Diseases of Swine

Location: Virus and Prion Research

Title: Sequence comparison of historic and contemporary strains of Senecavirus A

item BUCKLEY, ALEXANDRA - Oak Ridge Institute For Science And Education (ORISE)
item Michael, David
item GUO, BAOQING - Iowa State University
item VAN GEELEN, ALBERT - Iowa State University
item YOON, KYOUNG-JIN - Iowa State University
item Lager, Kelly

Submitted to: Research Workers in Animal Diseases Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 10/15/2018
Publication Date: 12/3/2018
Citation: Buckley, A., Michael, D.D., Guo, B., Van Geelen, A., Yoon, K., Lager, K.M. 2018. Sequence comparison of historic and contemporary strains of Senecavirus A. Research Workers in Animal Diseases Conference Proceedings [abstract]. Paper No. 267.

Interpretive Summary:

Technical Abstract: Introduction Seneca Valley virus (SVV), a ~7.2 kilobase picornavirus, was recently proven to be a causative agent for vesicular disease in swine, but speculation remains surrounding the sudden increase in SVV cases starting in the summer of 2015 even though the virus had been detected sporadically in the United States since the late 1980s. The objective of this study was to compare the sequences of 3 historical and 3 contemporary SVV viruses isolated from experimental samples. Materials and Methods Pigs (16-20 weeks old) were split into 6 groups each inoculated with a different SVV isolate (SVV 2001, Can 2011, HI 2012, IA 2015, SD 2015, NC 2015). SVV was detected by PCR in each pig following challenge, and one sample from each group was selected for virus isolation and subsequent genome sequencing by the Sanger method. Nucleotide sequences were aligned and the amino acid (AA) sequence was determined for the single open reading frame (i.e., polyprotein) for all 6 isolates. Results The six SVV polyproteins had a predicted AA identity of 97.5% or greater, and without SVV 2001 included in the analysis, it was 99.2% or greater. Some regions of the proteins were highly conserved (100%) among the 6 isolates such as VP4 (71 AA, internal structural protein) and 3B (22 AA, genome linked polypeptide (VPg)), while other proteins had more variable regions. Major external structural proteins VP1 (264 AA) and VP3 (239 AA) were 96.2% and 95.8% conserved respectively. Non-structural protein 3A (90 AA, unknown function) and 2A (9 AA, predicted to perform the ribosome-skipping function) were both only 88.9% conserved among the 6 sequences. Distinctively, SD 2015 was the only isolate to have an amino acid change to the 2C, 3A cleavage site. All other polyprotein cutting sites were conserved. Conclusions This study provides more information about sequence differences between historic and contemporary isolates of SVV, though all isolates were able to induce vesicular disease in swine. Further research will be required to determine whether these differences contributed to the sudden increase of SVV cases in the United States.