广东省翁源县一起麻疹暴发的血清学和分子生物学研究

Study on Serology and Molecular Biology of A Measles Outbreak in Wengyuan County of Guangdong Province

目的 分析广东省翁源县一起麻疹暴发的原因。方法 收集 2 0 0 1年 12月广东省翁源县暴发麻疹流行资料 ,并从中收集病例急性期血清和咽拭子各 6份 ,进行血清学检测 ,病毒分离和中和实验 ;通过RT PCR扩增麻疹N基因碳末端 5 89个核苷酸 ,并进行测序和种系分析。结果 麻疹暴发流行累计发病 2 2例 ,6份病例血清的麻疹IgM抗体阳性率 83 3% ,6份咽拭子仅分离出一株麻疹病毒 (韶关株 ) ,该麻疹流行株不同于中国疫苗株 (S 191) ,鉴定为H1基因型 ;和目前国外流行株相比在核苷酸水平变异最大可达 12 4% ,和目前国内H1流行株相比在核苷酸水平变异在 1 1%～ 2 7% ;中和实验表明麻疹疫苗免疫后血清能够中和该野病毒 ,但其中和的滴度比中和疫苗株低 2至 4倍。结论 麻疹基因变异不会引起新的流行 。

Objective To explore the cause of a measles outbreak in Wengyuan County.Methods Data on the measles outbreak in December 2001 were collected in 1～7 days after the onset of symptoms and six paired samples of serum and throat-swabs were collected for serological detection, virus isolation and neutralization test. A 589bp fragment of the C-terminal of the nucleoprotein (N) gene was amplified by RT-PCR and subjected to sequence and phylogenetic analysis using DNASTAR software. Results A total of 22 cases were found in this measles outbreak. Measles IgM positive rate was 83.3%(5/6). Only 1 strain (Shaoguan strain) was isolated from 6 throat-swabs. Shaoguan strain was distinct from the vaccine strain (S-191) and the divergence at the nucleotide level with foreign strains up to 12.4% and with domestic H1 strain was from 1.1%～2.7%. The serum vaccinated with S-191 could neutralize Shaoguan strain but the titer was 2～4 times lower than that of vaccine virus. Conclusion The mutation in measles virus did not lead to new measles epidemic; the lower level of measles antibody was the direct reason of this measles outbreak.