| Objective Measles is a worldwide,acute and highly contagious disease that affects mainly children.Although measles vaccine has been proven complete and effective in the past 40 years,measles is still an important cause of children death in developing country.Measles was responsible for 454,000 deaths in 2004 and most of them were children. According to WHO it can determine if new measles cases indicate new prevalence by investigating measles virus genotype.Therefore,one of the most important tasks of measles control is molecular epidemiology surveillance in laboratory study.This paper carried on the study of genotype and molecular epidemiology of the measles virus in Kunming, in order to find out the variation condition of the native measles virus and the relativity between the measles virus genotype and the clinical presentations of the patients.It provided scientific evidences for surveillance and prevention of measles.Methods Venous blood specimens of 38 patients who were during the acute contagious period were collected,then by using Enzyme-linked immunosorbent assay procedure to detect the IgM antibody of measles virus in these serum specimens.Meanwhile,30 urine specimens of these 38 children were collected.The 516 nucleotide sequence of the COOH-terminal of nucleoprotein(N)gene of these isolates were amplified by using RT-PCR.The amplified products were sequenced and the sequences were compared with references viruses from Genebank. The phylogenetic analysis was based on the 543 COOH-terminal nucleotide sequence of N gene.Meanwhile,clinical and epidemiological datas were collected in order to carry on the analysis of clinical epidemiology.Results1.All of the IgM antibodies in the 38 measles patients serum were positive,and the positive rate was 100%.7 measles viruses were isolated from the 30 urine specimens,and the positive rate was 23.33%.The measles virus could be isolate from the patient's urine specimen within the 6 days after rash.2.4 strains of measles viruses were chose randomly from the 7 strains of measles viruses isolated in the urine specimens in order to sequence.The sequence analysis was based on the 516 COOH-terminal nucleotide sequence of N gene.It showed that all of the 4 strains belonged to H genotype by comparing with the 23 stand references measles viruses from Genebank.3.The phylogenetic analysis based on the 543 COOH-terminal nucleotide sequence of N gene of the 4 strains showed that all of them were H1a genotype by comparing with the prevalent references viruses in China including China93-7(H1),China93-2(H1a),China94-7(H1b)and China94-1(H2).4.The average genetic distances in nucleotide sequence of these 4 strains to H1 genotype,China93-7,H2 genotype,China94-1 and H1a genotype,China93-2,were 0.031～0.0470,332～0.3980 and 0.010～0.033,respectively.The average genetic distance in nucleotide sequence within the 4 strains was 0.005～0.040.The average genetic distances in amino acid sequence of these 4 strains to H1 genotype,China93-7,H2 genotype,China94-1 and H1a genotype,China93-2,were 0.088～0.1490,205～0.2820 and 0.003～0.066.Within the 4 strains the average genetic distance was 0.010～0.073.The findings indicated that the main genotype was H1a genotype in Kunming.5.The sequence identity matrix of 4 strains showed that the homology of nucleotide sequence was 96%～98.9%(6～22 nucleotide variation) and that of amino acid sequence was 95.6%～99.6%.The homology of nucleotide and amino acid sequences were 95.9%～99.7%,96.9%～99.8%and 89.9%～94.8%,94.8%～99.7%respectively,when compared with that of the H1 genotype(China93-7)and H1a genotype(China93-2).6.In this study,the youngest child was 51 days old and the oldest one was 11 years old.There were 30 children younger than 2 years old,and it counted 78.95%of all the 38 patients.It indicated that the leading patients were the children younger than 2 years old.The ratio of male to female was 1.53:1,and male patients were more.7.The sequence analysis of the 4 strains randomly chose from the 7 strains isolated in the urine specimens showed that all of them was H1a genotype,but the clinical presentations were so different.It indicated there was not apparent relativity between them.8.In this study it found the measles patients were sporadic.In urban the patients were more in Wuhua and Xishan district;in rural Luquan's patients were more.9.81.58%of the 38 children didn't get immunization or were not sure if they had gotten immunization.Conclusions1.Currently the main prevalent genotype of measles virus is H1a genotype and it is consistent with the genotype of native prevalent measles virus strain in 2005 of Yunnan province.There is no apparent variation in nucleotide and amino acid sequence.H1b genotype and H2 genotype aren't detected.2.There is not apparent relativity between the genotype of measles virus and the clinical presentations of the patients.3.The age range of measles patients is wide,but the leading patients are the children younger than 2 years old and most of them didn't get immunization.
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