Animal feed and feed ingredients have recently been investigated as sources of pathogen introduction into farms and as a potential source of infection post-consumption. Survival of several viruses for a prolonged period has been demonstrated in feed. Here we determined the rate of decay of Senecavirus A (SVA) in swine feed ingredients as a function of time and temperature and established half-life estimates for the virus. Select feed ingredients were spiked with a constant amount of SVA (105 TCID50 ) and incubated at 4°C, 15°C and 30°C for up to 91 days. Virus viability and the presence of viral RNA were assessed in samples collected over time. At the three different temperatures investigated, dried distillers’ grains with solubles (DDGS) and soybean meal (SBM) provided the most stable matrix for SVA, resulting in half-lives of 25.6 and 9.8 days, respectively. At 30°C, SVA was completely inactivated in all feed ingredients and in the control sample, which did not contain a feed matrix. Although virus infectivity was lost, viral RNA remained stable and at consistent levels throughout the experimental period. Additionally, the ability of SVA to infect swine via ingestion of contaminated feed was investigated in 3-week old, weaned pigs. Animals were provided complete feed spiked with three concentrations of SVA (105 , 106 and 107 per 200 g of feed) and allowed to naturally consume the contaminated feed. This procedure was repeated for 3 consecutive days. Infection of pigs through consumption of contaminated feed was confirmed by virus neutralization assay and the detection of SVA in serum, fecal swabs and tonsils by rRT-PCR, with evidence of replication in tonsils and virus shedding in feces. Our findings demonstrate that feed matrices are able to extend the survival of SVA, protecting the virus from decay. Additionally, we demonstrated that consumption of contaminated feed can lead to productive SVA infection. This article is protected by copyright. All rights reserved.
Caserta L, Noll J, Singrey A, Niederwerder M, Dee S, Nelson E, Diel D. Stability of Senecavirus A in animal feed ingredients and infection following consumption of contaminated feed. Transbound Emerg Dis. 2021 Sep. https://doi.org/10.1111/tbed.14310