Decoding the Maternal-Foetal Immune Dynamics Against PRRSV

The porcine reproductive and respiratory syndrome virus (PRRSV) is one of the most significant infectious agents in swine production worldwide. Infection with the virus leads, on the one hand, to reproductive disorders in sows and, on the other hand, to respiratory diseas and reduced growth performance in pigs of all age groups. Additionally, the virus impairs the function of various immune cells, which is why PRRSV is considered a facilitator of bacterial secondary infections. Controlling PRRSV is therefore crucial for maintaining the health of pig herds and improving animal welfare, while also contributing to the reduction of antibiotic use. Currently, modified live virus vaccines are predominantly used to combat PRRSV, but their efficacy and safety are often questioned. Research aimed at improving the understanding of disease development, immune response, and vaccine development has primarily focused on the respiratory form of the disease. In contrast, the mechanisms underlying reproductive disorders caused by PRRSV infection are comparatively underexplored. The goal of our project is to investigate the local immune response following PRRSV infection within the uterus of sows during the last third of gestation, the phase in which PRRSV is transmitted in utero from the sow to her piglets. Using a specific, genetically uniform pig line, we aim to examine whether the responses of different immune cells within the uterus are protective or rather harmful to the piglets in utero. An excessive immune response could damage the placenta through local inflammatory processes, potentially leading to the death of the piglets. Furthermore, we aim to determine whether local immune cells in the uterus that specifically target PRRSV originate from the maternal or fetal side of the uterus. If maternal cells are indeed found to cross the placental barrier, vaccination and treatment strategies could be reconsidered in the future. Additionally, we plan to culture precision-cut tissue slices of the uterus for several days to develop a laboratory model that could replace the use of live animals for studying local mechanisms within the uterus. In summary, this research project aims to initiate new research directions, such as fetal immune priming, while simultaneously providing actionable insights into PRRSV pathogenesis and control. These advances are expected to improve the health and welfare of pigs and other livestock species and lay the foundation for innovative solutions to challenges in animal health.