Primary Analysis Of Measles Viruses Molecular Epidemiology In Tianjin

Objective: To investigate the genotype of the measles virus epidemic strains in Tianjin according to the patients suffered measles in 2002, and to establish the method of molecular virology in our laboratory.Methods: Twelve measles viruses isolated from urine specimens of measles patients of Tianjin in 2002 were revived using B95a cell line and extracted total RNA, then detected with RT-PCR. All of them got the special fragment of 590 nucleotides of COOH-teminal of nucleoprotein(N) genes. These RT-PCR products of 12 samples were cut with restriction fragment length polymorphism analysis, we choose 3 strains of measles virus N gene fragment to reconstruct the new plasmid with PMD-18T Vector. The three new plasmids were sequenced and analyzed with gene tree.Results: After the RFLP analysis using Ben I ,we got two kinds of result and choose 3 N gene fragment from these two kinds to colone. The sequence analysis of 456 nucleotides of N gene fragment indicated that all of them were members of HI genotype, one was Hlb subgroup, two were Hla subgroup. The two strains of Hla subgroup differed from the strain of Hlb subgroup by 3.07-4.17% at the nucleotide level in the COOH-terminal of N gene. These 3 Tianjin measles virus strains were differed from genotype A at 6.36~7.23%, from genotype HI at 1.53~2.41%. There were 16 mutations of amino acid in these 3 strains differed from genotype A.Conclusion: These results suggested that the measles viruses of 2002 in Tianjin belongs to genotype HI.The method in this study can be used to continue to survey the mutation of measles virus strains in Tianjin, it is very important for our country to accelerate measles control and eliminate measles in the future.