Genetic characterization of hemagglutinin protein of measles viruses in Hokkaido district, Japan, 2006-2015.

Strains of measles virus of genotypes D5, H1, D4, D8, and B3 were detected among epidemic, endemic, imported and import-associated cases in Hokkaido district, Japan, during 2006-2015. In the present study, their antigenic features were evaluated by determining the complete nucleotide sequences of their hemagglutinin proteins, which are a major target for neutralizing antibodies, and their amino acid sequences deduced. It was found that the hemagglutinin proteins of these strains had several novel amino acid changes in some functional regions. Although these strains have not caused further infections thus far, these antigenic changes should continue to be monitored to maintain their elimination status.