Genetic characterization of Chinese measles vaccines by analysis of complete genomic sequences

The complete genomic sequences of two Chinese measles vaccine viruses, Shanghai-191 (S-191) and Changchun-47 (C-47), were determined and compared to the sequences of other measles vaccine strains as well as the prototype measles strain, Edmonston wild-type (Edwt). Compared to Edwt, S-191 and C-47 had 49 and 43 nucleotide changes, respectively. These differences were found at 52 nucleotide positions that were not found in other vaccine strains. Phylogenetic analysis of the all of the available genomic sequences for measles vaccines showed that S-191 and C-47 were most closely related to the Leningrad-4 strain. S-191 and C-47 shared conserved vaccine virus-specific amino acid changes in the phosphoprotein (P), V, C, matrix (M), and hemagglutinin (H) that could represent important targets for future studies aimed at understanding the molecular basis of attenuation. In addition, S-191 and C-47 had several unique amino acid changes including 13 positions that differed from Edwt. This is the first comparison of the complete genomic sequences of Chinese measles vaccines to the sequences of other vaccine strains.