ROLE OF CD8+ T CELLS IN IMMUNITY AGAINST FLAVIVIRUSES.

Flaviviruses are zoonotic encephalitogenic pathogens of humans and animals that are transmitted by arthropod vectors. Effective vaccines against all but the yellow fever virus and the Japanese encephalitis virus among flaviviruses have eluded the persistent efforts of researchers. CD8+ cytotoxic T lymphocytes play a critical role in control of intracellular pathogens and hence are expected to contribute significantly to protection against flavivirus disease, while their ability to destroy infected neurons is bound to result in damage to the central nervous system (CNS). This review summarizes scientific investigations that revealed the wide spectrum of effects of CD8+ T cells both in virus control within the CNS as well as the range of pathologies exhibited by CD8+ T cells during infections by the individual members of this genus. The unique cross-reactive nature of CD8+ T cells specific to numerous flaviviruses and their implication for vaccine design are discussed.