.2000-2008 China H-<sub> 1 </ Sub> Genotype Of Measles Virus Hemagglutinin And Blood Aerolysin Genetic Characteristics

Measles is an acute respiratory infectious disease caused by Measle viruses,belongs to "C" class infectious disease in China.Now measles still remains a substantial health risk despite extensive vaccination efforts,and the incidence rate hold the high level in some areas in China.The goal of measles elimination before 2012 has been made in China.Therefore,strengthening the routine immunization, improving second-dose vaccination rate and evaluating vaccine-preverntable efficiency are crucial for the elimination goal.In this study,we focus on measles viruses circulating in China from 2000 to 2008.Variation characristic of the significance protein of measles virus,the gene diversity between epidemic measles virus strains and the vaccine strains,and vaccine-preverntable efficiency were studied.Objective Study the genetic characterization and variation principle of Fusion(F),haemagglutinin(HA) protein of H1 genotype of wild-type measles virus circulated in China from 2000 to 2008,estimate vaccine-preverntable efficiency,analysis the variation of key amino acid site of F and HA protein.Methods 30 isolates of H1 genotype sent by provincial Measles Laboratories measles viruses were selected based on N-COOH phylogenetic tree.RNA from measles isolates were extracted,Then complete coding regions of fusion(1662nt) and hemagglutinin(1 854nt) were amplified by RT-PCR and sequenced.Phylogenetic tree were constructed,and nucleotide and amino acid diversity were further analysised.Results Among 30 representative strains circulated in China during 2000 to 2008, the homology of nucleotide acid and amino acid of hemagglutinin were 97.1%～99.6% and 96.4%～100%respectively,and the homology were 94.3%～95.5%and 94.8%～95.7%when compared with Chinese vaccine strains;Among 30 representative strains circulated in China during 2000 to 2008,the homology of nucleotide acid and amino acid of fusion were 99%～100%and 98.1%～100%respectively,and were 98.1%～98.6%and 98.1%～100%respectively compared with Chinese vaccine strains; Though amino acid aliment,we found one N-glycosylation site in 240^th amino acids disappeared among H_1a sub-genotype strains,but not for H_1b sub-genotype strains.No any change was found in three N-glycosylation sites in Fusion protein.The 546^th amino acid of HA protein in all 30 strains changed from glycine to serine when compared with Edmonston strains.Conclusion The nucleotide and amino acid variation of fusion and hemagglutinin is unapparent,all of the key amino acid is unvariated except the 240^th and 546^th amino acids in hemagglutinin.Because the measles vaccine in China can prevent measles infection and the measles virus can cause the classic CPE on sensitivity cell,so we suppose that structure and fuction of Fusion and hemagglutinin is stable.No obvious variation regular and mutation accumulation were found based on sequence alignment results,and we believe these variations belong to random shift.