CategorySwine Health - General Disease
Date Full Report Received04/06/2019
Date Abstract Report Received04/06/2019
Funded ByNational Pork Board
Senecavirus A is an emerging picornavirus that causes foot-and-mouth disease (FMDV)-like vesicular disease in pigs. Outbreaks of SVA in pigs require a complete foreign animal disease (FAD) diagnostic investigation and FAD rule out. Due to its similarity with FMD and other vesicular FADs of swine, USDA restricts movement of animals affected by SVA until a final diagnosis is achieved. The goal of the present study was to assess the effect of common production stressors on Senecavirus A (SVA) disease severity and to determine occurrence or not of the carrier state in SVA infected animals. By using a sow infection model (cull and pregnant sows) we investigated 1) the effect of stressors on severity and time to vesicular lesion development; 2) the occurrence of carrier animals; and 3) the effect of stressors on SVA recrudescence (virus shedding and/or overt disease) from potential carrier animals. Results from our study showed that sows infected with SVA immediately after transportation developed vesicular lesions slightly earlier than sows that were acclimated in our animal facility for 1-week prior to infection. The lesions were also slightly enlarged in the transportation group, when compared to lesions observed in acclimated animals. To determine if infected animals become carriers of the virus and to assess the effect of stressors (transportation, immunossupression and parturition) on disease re-occurrence and reactivation from persistence, we inoculated a fourth group of sows during gestation and monitored all inoculated sows for approximately 60 days post-inoculation. On day 42 post-inoculation one sow of each stressor group was euthanized to determine the presence of SVA in the tonsil of infected animals. The remaining animals (n=4/group) were monitored for additional 14 days after stress stimulation. Piglets born from animals in group 4 were also monitored daily for the development of disease and virus excretion. PCR testing of the tonsil of animals euthanized on day 42, confirmed the presence of SVA genome in this tissue. Additionally, animals from all groups excreted SVA in feces and oral and nasal secretions. Testing performed in the tonsil of the animals at the end of the experiment on day 60 post-inoculation also demonstrated the presence of SVA genome in this tissue. Most importantly, infectious SVA was recovered from the tonsil of two sows on day 60 post-inoculation. Together, the results from the present study suggest that transportation stress may have a slight effect on initiation of SVA and on the severity of the disease. We also show that SVA induces persistent infection in infected animals and the virus that is shed by carrier animal can be transmitted infect contact piglets. These studies revealed important and new aspects of SVA infection in pigs.