MOLECULAR EPIDEMIOLOGY OF RUBELLA BY NUCLEOTIDE-SEQUENCES OF THE RUBELLA-VIRUS E1 GENE IN 3 EAST-ASIAN COUNTRIES

Twenty-six strains of rubella virus were compared with each other for a molecular epidemiologic study of the virus in three East Asian count ries, using the E1 gene of 1443 nucleotides and the following 41 nucle otides in a noncoding region. Nucleotide substitution rates among stra ins were 0.0-9.4/100 nucleotides. A phylogenetic tree drawn indicated that 2 of 3 Chinese strains were quite different from the other 24 str ains; all isolates in the 1960s were classified into a single group in dependent of the place of isolation, which includes isolates from Japa n, the United States, and the United Kingdom; 11 strains of Japanese i solates collected during 1976-1991 made one subbranch derived from the 1960s group; and 2 isolates from the northeast part of Japan in 1990 made a third but minor unique branch. Therefore, at least two groups o f the virus cocirculated in Japan around 1990. Antigenic variation of the virus was very small among these strains.