331 A MONKEY MODEL TO STUDY MEASLES VACCINATION STRATEGIES

Abstract

In humans measles is believed to confer lifelong immune protection against re-exposure to measles virus (MV), which appears largely based on persistence of MV neutralizing (VN) antibodies and the presence of MV specific cytotoxic T lymphocytes (CTL). Apart from humans several non human primate species can be infected with MV. However, the pathogenesis of this infection and the basis of immune protection in these animals is largely unknown. Here we show that cynomolgus monkeys (Macaca fascicularis) can be experimentally infected with a wild-type strain of measles virus (MV-BIL), that has recently been isolated from an outbreak of measles in school children in The Netherlands. Following intratracheal inoculation with different infectious doses, the virus could be isolated from peripheral blood mononuclear cells (PBMC), lung lavage cells and pharyngeal cells. Specific serum IgM, IgG and neutralizing antibody responses as well as MV-specific T cell mediated immunity were induced, quite similar to responses observed in infected children. Monkeys vaccinated with attenuated measles vaccine (MV-Schwartz) also showed a PBMC associated viraemia and specific IgM responses. They proved to be protected from intratracheal infection with MV-BIL 9 months after immunization. This model is currently used for the evaluation of new generations of vaccines and vaccination strategies in the framework of a WHO vaccine evaluation program.