Immune responses against measles virus in cynomolgus monkeys.

Measles virus (MV) induces profound suppression of the immune response during and for weeks after acute infection. On the other hand, virus-specific immune responses that mediate viral clearance and confer long-lasting immunity are efficiently generated. To investigate this paradox, we studied the immune responses to MV using a monkey model of acute measles. Cynomolgus monkeys were experimentally infected with wild-type MV (MV-HL) and showed marked leukopenia associated with a steady reduction in CD4+ T cell numbers for 18 days post-inoculation. Transient expression of interferon and IL-6 were observed in the serum between 4 and 6 days post-inoculation, and IL-10 levels increased after 11 days post-inoculation. Interestingly, IL-8 showed a three-peak increase that correlated with an increase in neutrophils. A non-human primate model of measles allows the early immune response against MV to be studied in more detail.