are pathogen-associated molecular recognition receptors responsible for signaling
intrusion by pathogens. These receptors are present on porcine NK cells and appear to perform an important
role in innate and adaptive immunity to viral
pathogens affecting pigs. Surface proteins belonging to the swine leukocyte antigen (SLA)
gene complex or major histocompatibility complex (MHC) play a significant role in the cellular and
humoral immune response . Genetic variability of the SLA complex has been demonstrated in different breeds of pigs.