Molecular Epidemiology Of Measles Virus In Qinghai From2000to2011

Objective To study the genetic characterization of measles viruses isolated from Qinghai province from2000to2011. To identify the source of the virus, trace the transmission pathways and analyze the distribution genotype. To accumulate the baseline database of the genetic and amino acid variation of the endemic measles viruses, and to find the possible imported measles virus abroad.Methods The measles virus was isolated from the throat swab and (or) urine with Vero/SLAM cell line and detected by reverse transcript polymerase chain reaction (RT-PCR) method, which can amplify the676nucleotides sequence corresponding to the carboxyl terminus of measles virus N gene. The phylogenetic tree based on the450nucleotide acids of carboxyl terminus of N gene was constructed and the homology similarity was analyzed. And then, the sequence of entire coding region of H gene of non-H1genotype wild-type measles viruses was analyzed. Analysis the N protein C-terminal150amino acid variation of vaccine strains of measles H1a S191, China representative strains of China9322and stains from2000to2011measles epidemicResults19strains of wild measles virus were isolated from2000to2011year, which are H1genotype of H1a gene subtypes. N gene COOH terminal sequence analysis results of19strains of Hla isoforms of wild measles virus showed that between them the nucleotide homology is96.0%～100%,92.7%～100%amino acid sequence homology; and H1a genotype representative strains of Chin9322nucleotide homology is97.1%～99.5%,94.0%～99.3%amino acid sequence homology. To Chinese measles vaccine strain S191as a benchmark,19strains of measles virusisolated in Qinghai province from2000to2011consists of32amino acid replacement, replacement rate was21.3%(32/150), there are16amino acids of all variants, there are16sites as part of amino acid variation; The difference between19strains of measles virus and Chinese measles Hla representative strains of China9322amino acid is1-8, from2009to2011,10strains of measles virus and China9322amino acid differences increased significantly; and from2000to2005, measles virus strains prevalent from2009to2011, measles virus N protein gene sequence deduced amino acid are common3amino acid changes, in422loci from glycine (G) mutation to serine (S), at457sites by S variation for G, at497loci from arginine (R) variation for lysine (K).Conclusion From2000to2011in Qinghai province popular wild measles virus in native subtype Hla absolute advantage gene subtypes, not found in Hlb and Hlc subtypes; from2000to2005the separation of the measles virus in the same small branch, forming a chain of transmission, from2009to2011separation to measles virus in another small branch, forming a chain of transmission. As the year increase,19strains of measles virus with Chinese measles vaccine strains S191and Chinese measles Hla representative strains of China9322between amino acid differences exhibited an increased tendency. From2009to2011of the measles virus N protein gene sequence deduced amino acid are common to the3amino acid variation, tips should pay close attention to N protein amino acid mutation status and changing trend.