Natural cytotoxicity detected in swine using Aujeszky's disease virus infected targets.

Using percoll gradients and standard B and T cell depletion techniques, porcine lymphocytes were investigated for their ability to show natural killing (NK) of many targets, including Aujeszky's disease virus (AJDV) infected cells. Although it was possible to enrich for NK activity using these techniques it was not possible to define a distinct subpopulation of NK cells. It was noted that porcine NK cells consistently showed a preferential lysis of AJDV infected cells in comparison to uninfected cells. Furthermore, pretreatment of these effector cells with virus or interferon increased their lytic ability but did not alter the degree of preference on the lysis of target cells shown by untreated effectors. Although in vitro results suggested that porcine NK activity might be an efficient mechanism for controlling AJDV infections in the animal, experiments designed to monitor NK levels in vivo were unable to demonstrate this. The possible explanations for this are discussed.