#18-034

Complete

Date Full Report Received

05/28/2020

Date Abstract Report Received

05/28/2020

Investigation

Institution:
Primary Investigator:

Funded By

In the recent years, cases of vesicular disease in pig due to Senecavirus A (SVA) infections have been responsible for an emerging concern in the swine industry for being clinically indistinguishable from high-consequence foreign animal diseases, including foot-and-mouth (FMD) disease. Data from previous studies showed that the virus can be found in the tonsils of naturally-infected pigs up to approximately 90 days after showing clinical disease, suggesting a potential for establishing persistent infections and an asymptomatic carrier state, and that specific mutations on the viral capsid may be driving the ability of contemporary SVA isolates to escape from the host immune responses previously built against historical isolates. This research project’s goal is to investigate the ability of SVA to induce asymptomatic carrier state in pigs, and evaluate the susceptibility of pigs experimentally infected with a contemporary isolate after previous exposure with an historical strain.
Forty nine days after inoculation with the contemporary or historical strains, 2/3 and 4/4 necropsied animals respectively showed positive PCR results in the tonsils of the soft palate. Tonsil scraping showed to be a promising method to detect SVA RNA in the tonsils of clinically recovered animals, by detecting SVA in 39.1% of the animals from both groups 48 days after exposure. Shedding of SVA in saliva and feces was greatly reduced after the re-challenge with a contemporary strain in both groups previously infected with either the historical or contemporary isolate. These results show that animals can be asymptomatically infected with SVA after being thought to be clear of the virus, and could potentially be a source of infection to naïve animals. Also, animals that were previously exposed to a historical or contemporary strains were not susceptible to the contemporary strain in the second inoculation.