Differential induction of type I interferons in macaques by wild-type measles virus alone or with the hemagglutinin protein of the Edmonston vaccine strain.

Measles vaccines are highly effective and safe; however, the mechanism(s) underlying their attenuation has not been well understood. In this study, type I IFNs (IFN-α and IFN-β) induction in macaques infected with measles virus (MV) strains was examined. Type I IFNs were not induced in macaques infected with wild-type MV. However, IFN-α was sharply induced in most macaques infected with recombinant wild-type MV bearing the hemagglutinin (H) protein of the Edmonston vaccine strain. These results indicate that the H protein of MV vaccine strains may have a role in MV attenuation.