HIV and SIV CTL escape: implications for vaccine design

Cytotoxic T lymphocytes (CTLs) have a central role in the successful control of immunodeficiency virus infection. Evasion of this immune response through CTL escape is therefore an important factor in HIV and simian immunodeficiency virus pathogenesis. During the course of an infection, the precise timing of the occurrence of escape mutations and their location in the viral genome can indicate the efficacy of certain CTL specificities and the cost to viral fitness of particular escape mutations — factors that are highly relevant to vaccine design. Also crucial for vaccine design is the extent to which CTL escape is driving the evolution of HIV at the population level. Here, we highlight the important lessons that can be learned from immunodeficiency virus CTL escape.