Studies on the Cell-mediated Immunity in Chickens Infected with Marek's Disease Virus

Benda V.: Studies on the Cell-Mediated Immunity in Chickens Infected with Marek's Disease Virus. Acta vet. Brno, 47,1978: 197-201. The effect oflymphocytes from MDV -infected chickens on HCr-labelled HPRS line 1 Iymphoblasts derived from an from an MDV-induced lymphoma was investigated by using a cytotoxicity test (CTT). In comparison with the control and vaccinated chickens, chickens inoculated with MDV showed cytotoxic activity as long as 11 weeks after infection. This supports the view of an important role of the cell-mediated immunity in the pathogenesis of Marek's disease. nCr cytotoxic assay, turkey herpesvirus. Marek's disease (MD), a herpesvirus-caused Iymphoproliferative disease of chickens (Churchill and Biggs 1967), is not only an economically important zoonosis, but also a suitable experimental model for studying the pathogenesis of the virus-induced tumour diseases. Attention has been directed recently towards the mechanism of natural and vaccine-induced immune response of chickens against infection with the oncogenic Marek's disease virus (MDV), perhaps in connection with the data reported on variations in the reliability of MDV vaccines. The cell-mediated reaction, more precisely, the reaction mediated by sensitized T lymphocytes, which tends to eliminate cells bearing MDV -specific virus antigens of MD-specific tumor antigens, the latter being designated MATSA (Witter et al. 1975), is presumed to predominate in this case. This comunication presents some findings supporting the assumption that an antitumour immunity exists in MDV-infected chickens. Materials and Methods Chickens Leukosis-free Rhode Island Red chickens (Biggs et al. 1968), which are susceptible to MD (experiment A),and chickens of the inbred line WA (Hala et al. 1966) (experiment B), both from the Institute's own flock, were maintained under conventional conditions, each group kept in separate room. The sacrificed and dead chickens were examined for the presence of MD lymphomas. Viruses MDV, strain GA of acute MD virus (Eidson and Schmittle 1968), was propagated in susceptible chickens, and infection was performed by intraperitoneal injection of heparinized blood. The FC-126 strain of herpesvirus of turkeys (HVT), used for vaccine preparation (Witter et al. 1970), was propagated and inoculated in chicken embryo fibroblasts. The HPRS line 1 Iymphoblasts, originally derived from an MDV-induced ovarian lymphoma (Powell et al. 1974), were kindly provided by Dr. P. C. Powell, Houghton Poultry Research Station, England, in 1976 and have since been cultured in suspension in this laboratory. This line consists almost exclusively ofT cells which bear a MATSA on their surface in 90 % (Matsuda et al. 1976).