T cell-mediated clearance of porcine reproductive and respiratory syndrome virus (PRRSV) from the lung characterized by machine learning analysis in vaccinated and unvaccinated pigs.

Porcine reproductive and respiratory syndrome (PRRS) modified live virus (MLV) vaccines likely confer partial protection against heterologous wild type challenge through broadly reactive T cells. Therefore, the efficacy of Ingelvac PRRS® MLV alone and reconstituted with Ingelvac CircoFLEX® was assessed by comparing the ability to induce a robust cell-mediated immune response and confer protection against challenge. This study utilized both classic immune assays and machine learning software for measuring the cell-mediated immune response to PRRSV vaccination and challenge. Both vaccine groups had significantly reduced viremia, lung viral load, gross and microscopic lung lesions and improved average daily gain compared to the mock vaccinated group. The T cell analysis in the lung revealed a robust response to PRRSV infection leading to marked clearance of virus from the lung in the absence of neutralizing antibodies.