Comparison of historic and contemporary strains of Senecavirus A

Authors: BUCKLEY, ALEXANDRA - Orise Fellow; GUO, BAOQING - Iowa State University; KULSHRESHTHA, VIKAS - Iowa State University; VAN GEELEN, ALBERT - Orise Fellow; YOON, KYOUNG-JIN - Iowa State University; Lager, Kelly

Submitted to: Research Workers in Animal Diseases Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 9/19/2017
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Objective One hypothesis for the sudden increase in SVA cases in the United States was that contemporary strains were more pathogenic than historical strains. Our objective was to study disease progression of historical and contemporary SVA isolates in growing pigs. Materials and Methods Commercial swine aged 16-20 weeks old (n=54) were split into 6 challenge groups (n=8) and 1 control group (n=6). Three historical isolates (2001, 2011, 2012) and three contemporary isolates (2015) with inoculum titers ranging from 105.1 – 106.8 TCID50/mL were given intranasally. Animals were regularly bled, rectal swabbed, and oral swabbed. Animals were also observed daily for any clinical signs of vesicular disease. The sampling period ranged from 0 days post inoculation (dpi) to 14 dpi. Serum and swabs were tested by real-time PCR for SVA nucleic acid detection. Serum was also tested for neutralizing antibody response to the challenge virus by virus neutralization assay and cross neutralizing antibodies to other challenge isolates. Results All isolates used in the study were able to induce clinical disease with the development of vesicles either on the coronary bands or the snout. The number of pigs presenting with clinical signs in each challenge group ranged from 5/8-8/8. All animals in each challenge group replicated virus. There were slight differences in onset and duration of shedding among the six different isolates, but overall most pigs were PCR positive for SVA in oral and/or rectal swabs by 4 dpi and were still shedding virus at 14 dpi. Neutralizing antibody titers to both homologous and heterologous strains used in this study are pending. Sequencing results and comparison between the 6 isolates is also pending. Conclusions This study demonstrated that vesicular disease can be experimentally reproduced in growing pigs with both historic and contemporary isolates of SVA. In addition, the results suggested there were not large differences in clinical presentation between strains. Further research will be needed to help determine the cause of the sudden increase in vesicular disease due to SVA infection in the United States swine population.