New genetic group of measles virus isolated in the People's Republic of China.

Genetic and antigenic characterization of 14 wild-type measles viruses isolated from four provinces in the People's Republic of China during 1993 and 1994 was conducted. Sequence analyses of the hemagglutinin (H) and nucleoprotein (N) genes indicated that 13 of the 14 Chinese viruses comprised a previously undescribed genetic group. Viruses from this unique group were the most genetically diverse measles viruses described, so far. The Chinese viruses differed from other wild-type viruses by as much as 6.9% in the H gene and 7.0% in the N gene at the nucleotide level. One of the 14 viruses was a member of the same genetic group that contains the Edmonston strain. Antigenic analysis using monoclonal antibodies to the H protein did not detect significant differences in binding patterns between the Chinese viruses and other wild-type measles viruses. In addition, representative viruses from the unique Chinese group were neutralized by both human post-vaccination antiserum and mouse antiserum against the H protein of the Edmonston vaccine virus. Viruses closely related to these Chinese viruses were also associated with importations of measles into the United States during 1997 from Vietnam and Hong Kong suggesting that viruses from this new genetic group continue to circulate in China and possibly other parts of Asia.