The analysis of the molecular epidemiology character of measles wild virus in Chaoyang District of Beijing， 2010 to 2012

Objective To understand the molecular epidemiology characters of measles wild virus in last three years in Chaoyang District of Beijing,and provide the scientific evidenceformeasles elimination in this region.Methods Vero/Slam cell were used for measlesviral isolationfrom the specimens collected from suspected measles cases in Chaoyang District of Beijing from 2010 to 2012,Fragment of 676 nucleotide acids of the carboxylend of nucleoprotein gene were amplified using reverse transcription-polymerase chain reaction(RT-PCR) method,and then the PCR products were directly sequenced and analyzed.In the end,phylogenetic tree was constructed based on 450 nucleotide acids of the carboxyl end of nucleoprotein gene,and homological analysis was performed at nucleotide acid level and amino acid level.Results 18 measles virus strains were all identified as H1 genotype,and H1 a Sub-genotype.The homology at nucleotide acid level among them was between 98.2％ and 100％ (0-8 nucleotide variation),the homology at amino acid level among them was between 95.3％ and 100％ (0-4 amino acid variation).Compared with Chin9322 the H1aSub-genotype reference strain,the variation at nucleotide acid level of 18 representative measles virus from Chaoyang District in Beijing was between 0.7％-1.6％ (3-7 nucleotide variation).There were 7 nucleotide sequence types,V1 to V7,in the 18 measles virus strains,5 types in 2010,1 type in 2011 and 3 types in 2012.V2 occurred in 2010 and 2012,V7 occurred in 2010 and 2011,other five types justoccurred in single year.Conclusions H 1a sub-genotype was the endemic genotype of wild measles virus circulated in Chaoyang District in Beijing during 2010 to 2012.One sequence type in a cluster of cases indicate that the transmission chains might exist.The measles wild virus with same nucleotide sequence occurred in 2010 and 2012. Key words: Measles viruses;  Sequence determination and analysis;  Genotype