Genetic characterization of measles virus isolated in Shanghai during 2004-2006

Abstract

Objective To carry out genetic characterization and molecular epidemiology study of the measles viruses(MV)isolated in shanghai from 2004 to 2006 for providing scientific basis for better immunization strategy and the goal of measles elimination.Methods Serum specimens were collected from the patients with suspected measles to detect anti-measles IgM by ELISA.Part of the nucleotide sequences of the C terminus of nucleoprotein(N)gene of these isolates were amplified by RT-PCR,and the amplicons were directly sequenced.The phylogenetic analysis was based on the nucleotide sequence about 456 bp of the C terminus of nucleoprotein(N)gene.Results Anti-measles IgM was detected in 132 of 148 serum specimens,and MV was isolated from 66 of 148 throat swabs,positive rates were 89.2% and 44.6%,respectively.The 66 strains of MV were genotype H1.All of them were subgenotype H1a except Shanghai04-5,which was subgenotype H1b.The sequence identity of 66 isolates showed that the homology of nucleotide sequences was 95.8%-100%,and that of amino acid sequences was 95.8%-100%.The homologies of nucleotide and amino acid sequences were 91.2%-93.2%and 86.8%-90.1%,respectively,when compared with that of vaccine strain S191,and those were 92.5%-93.4%and 88.2%-91.4% respectively when compared with vaccine strain changchun-47.Conclusions The wild-type MV strains circulating in shanghai were genotype H1 in 2004-2006,and the subgenotype H1a was the predominant one.There was one main transmission chain in 2005 and 2006,respectively,in shanghai. Key words: Measles virus; Genotype; Sequence analysis