We further identify that PRV-1 activation of CD8+ T cells likely initiates interferon gamma signaling cascades, and is affected to some degree by both PRV-1 and host genotype, whereby BC-PRV was associated with lower CD8+ T cell responses relative to NB- or NOR-PRV, while EU salmon showed higher CD8+ T cell sensitivity than either BC or NB-TR Atlantic salmon during the peak to early persistent phases of infection (6–10 wpc). The gene discussed is CD8A; the disease is breast cancer.