Differential effects of priming with DNA vaccines encoding the hemagglutinin and/or fusion proteins on cytokine responses after measles virus challenge.

Measles is associated with a million deaths a year in developing countries because of secondary infections. Morbidity is particularly severe in young infants. Both measles-induced immune suppression and atypical measles have been associated with a type 2 cytokine bias of the immune response. The role of individual virus proteins in the induction of these cytokine responses is unknown and could be important for the development of new vaccines. We have used a rhesus macaque model and DNA vaccines to investigate cytokine responses to the individual measles virus (MV) protective antigens, hemagglutinin and fusion. The hemagglutinin protein primed for a type 2 cytokine response, with suppression of interleukin (IL)-12 and preferential production of IL-4 after MV challenge. The fusion protein primed for a type 1 response with preferential production of interferon-gamma. Responses were modulated when both proteins were used for priming. Therefore, the specific proteins included in a new measles vaccine will affect the type of cytokine response elicited.