Efficacy of herpesvirus of turkeys vaccine against challenge with Marek's disease tumor cells.

Tests were made of the effectiveness of herpesvirus of turkeys (HVT) vaccine in preventing tumorigenesis following challenge with a neoplastically transformed Marek's disease tumor cell line (MSB-1). HVT vaccine prevented tumors due to MSB-1 inoculation whereas 21.4% of unvaccinated controls had tumors. The results support, but do not prove, the theory that HVT acts through enhancement of cell-mediated immunity against MDV-transformed cells. The drawbacks of using MSB-1 cells in this experiment and the need for true Marek's transplantable tumor cells are discussed.