Stability of Senecavirus A in animal feed ingredients and infection following consumption of contaminated feed

Abstract

Animal feed and feed ingredients have recently been investigated as sources of pathogen introduction to farms and as a potential source of infection to animals postconsumption of contaminated feed. 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 (10 5 median tissue culture infectious dose 50) and incubated at 4, 15 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 matrices 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 (10 5 , 10 6 and 10 7 per 200 g of feed) and allowed to naturally consume the contaminated feed. This procedure was repeated for three consecutive days. Infection of pigs through consumption of contaminated feed was confirmed by virus neutralization assay and the detection of SVA in serum, feces and in the tonsil of exposed animals by real-time reverse transcriptase PCR. 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.

Prolonged Viability of Senecavirus A in Exposed House Flies (Musca domestica)

“…Therefore, it is plausible that flies may be infected with comparable viral titers during feeding in naturally infected pig secretion, feces, or tissues. Whereas the SVA minimal infectious dose is unknown, a previous study demonstrated that pigs fed for three consecutive days with feed spiked with SVA containing doses as low as 10 5.0 TCID 50 /mL had RNA present in the feces and tonsils, and most of the exposed pigs also had viremia [12]. The prolonged viability of SVA in house flies may provide an opportunity for pathogen transfer over some distances due to the house fly flight range.…”

“…The differences in the viability of both SVA and SwPV in exposed flies are remarkable. Both viruses are known to be highly resistant under environmental conditions [12,25,26]. Whereas the study was not designed to identify whether the infectious virus was retrieved from the internal or external parts of the flies, one hypothesis for the prolonged SVA viability compared to SwPV is that SVA resisted the enzymatic digestion process in the flies.…”

“…These lesions are usually present in the snout, oral mucosa, and/or feet. Infected animals shed a significant amount of viruses through vesicular fluid, feces, nasal, and oral secretions [11,12]. SVA infection in pigs is usually self-limited, and most animals are clinically recovered in about two weeks.…”

Disruption of anthrax toxin receptor 1 in pigs leads to a rare disease phenotype and protection from senecavirus A infection

“…Senecavirus A continues to be an issue for swine producers as vectors, including mice and flies, are involved in the transmission of the virus within and between farms 4 , and SVA has been shown to be stable in several swine feed ingredients for up to a month 28 . Although vaccines are being developed, they have not conferred prolonged protection 29 ; thus, warranting the need for new strategies, such as gene editing that have resulted in resistance to porcine reproductive and respiratory syndrome virus (PRRSV) and transmissible gastroenteritis virus (TGEV) 30 , 31 .…”

Feed: A new pathway for the domestic and transboundary spread of viral pathogens of veterinary significance

“…Following the case studies are original articles, which bring forth new information regarding the stability and infectivity of foot and mouth disease virus (Stenfeldt et al, 2021), and Seneca Virus A (Caserta et al, 2021) in feed, the oral infective dose in feed, and the efficacy of feed additives as mitigants to reduce risk. We then explore the ability to sample feed correctly to maximise the sensitivity and specificity of detection, as well as how to manage viral contamination of feed at the level of the farm and the feed mill.…”