Differential expression in the porcine thymus upon infection by PRRSV, Influenza B or their coinfection

Authors: SARLO DAVILA, KAITLYN - Oak Ridge Institute For Science And Education (ORISE); SANG, YONGMING - Tennessee State University; MA, WENJUN - Kansas State University; Miller, Laura

Submitted to: World Congress of Genetics Applied in Livestock Production
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/24/2022
Publication Date: 7/3/2022
Citation: Sarlo Davila, K.M., Sang, Y., Ma, W., Miller, L.C. 2022. Differential expression in the porcine thymus upon infection by PRRSV, Influenza B or their coinfection. World Congress of Genetics Applied in Livestock Production. 9(11). https://doi.org/10.3390/pathogens9110934.
DOI: https://doi.org/10.3390/pathogens9110934

Interpretive Summary: Both Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) and influenza B (IBV) cause natural infections in pigs. PRRSV is the more common swine infection and can develop coinfections with IBV, a zoonotic virus able to infect humans. As a primary infection PRRSV can suppress the host immune system, leaving pigs susceptible to secondary infections such as IBV and contributing to the enormous economic impact of the disease. One component of this immunosuppression is the ability of PRRSV to affect the thymus and impair its normal function. This study investigates the host transcriptomic response in the thymus following PRRSV and IBV infections as well as their coinfection. What was found is that swine mount an immune response to PRRSV and PRRSV/ influenza B coinfections that initiate recovery but possibly plays a role in lung injury. The results also demonstrated that swine immune response will clear influenza B infections within a few days. The study results give insight into the ability of the swine immune system to deal with multiple respiratory infections which opens up new avenues for finding treatments. The study also indicates that the swine immune system clears influenza B infections quickly, minimizing the chance of infection in livestock workers.

Technical Abstract: Porcine Reproductive and Respiratory Syndrome (PRRSV) causes large economic losses and suppresses the host immune system, impairing thymus function and leaving pigs susceptible to secondary infections such as zoonotic Influenza B (IBV). Seronegative pigs at 3-4 week-old were split into four treatment groups: control; infected with Type 2 PRRSV NPB strain; infected with B/Brisbane/60/2008 virus; or coinfected with both viruses. Pigs from each of the four treatment groups were necropsied at 3-, 5- and 7-days post-infection(dpi) and thymus samples were collected for transcriptomic analysis. Differentially expressed gene (DEG) analysis was carried out using DeSeq2 and g:Profiler was used to identify significantly enriched pathways. Several pathways related to immune function were detected in the PRRSV and coinfected but not IBV samples, indicating that PRRSV infection persist and subvert the host immune system by downregulating genes involved in cytokine and interferon signalling and monocyte and macrophage signalling with the thymus.