Antiviral T cell-mediated immunity in Marek's disease

Abstract

MAREK'S disease (MD) is a herpesvirus induced lymphoma of chickens characterised by transient virus replication in lymphoid cells and transformation of T cells¹. Several mechanisms probably operate in resistance to Marek's disease, but there is indirect evidence that protective immunity is predominantly T-cell dependent² and comprises both antiviral³ and anti-tumour⁴ immune responses. Thus, a notable feature which distinguishes immunity to Marek's disease from immunity to other herpesvirus infections studied so far is that both effector and target cells are probably T cells and that both virus and tumour-specific antigens may act as targets for immunological attack. Using a plaque inhibition test as a measure of cell-mediated immunity, I show here that T cells obtained from immunised birds are sensitised to virus-specific antigens present at the surface of infected cells of both lymphoid and non-lymphoid origin. The results provide direct evidence for the role of T cells in eliminating infected leukocytes and in reducing the spread of Marek's disease virus (MDV) in vivo.