PRRSV-specific T cell responses show highly variable kinetics among individuals in virulent PRRSV-infected pigs. Cell-mediated immunity against PRRSV is broadly cross reactive among type 2 isolates of varying genetic distance. This cross reactivity does not extend to type 1 isolates. Total antibody responses are cross reactive, instead neutralizing antibody titers are specific for the challenge isolate. Homologous T cell responses show a positive association with homologous neutralizing antibody titers.