中山市6例疑似麻疹疫苗相关病例病原学特征分析

目的 分析中山市6例疑似麻疹疫苗相关病例的病原学特征。 方法 采集中山市2014－2015年6例疑似麻疹疫苗相关病例咽拭子样本并提取核酸,采用巢式PCR法扩增麻疹病毒核蛋白(N)基因羧基末端450个核苷酸片段并测序,分析其与世界卫生组织(WHO)参考株、麻疹病毒中国疫苗株沪₁₉₁(Shanghai₁₉₁,S₁₉₁)基因的亲缘关系、核苷酸与氨基酸序列相似度。 结果 6份样本中,2份未检出核酸,4份检出核酸,序列比对结果示3株病毒核苷酸、氨基酸序列相似度均为100%,与S₁₉₁株相比,核苷酸序列和氨基酸序列相似度也为100%,属于A基因型;1株病毒与Chin9322-H_1a株相比,核苷酸序列相似度为97.7%,氨基酸序列相似度为96.6%,为H_1a基因型。 结论 3例病例为疫苗株感染,1例为野毒株感染。

Etiological characteristics of 6 suspected cases of vaccine-associated measles in Zhongshan City

Objective To analyze the etiological features of 6 cases of suspected vaccine-associated measles in Zhongshan City. Methods Nucleic acids were extracted from throat swabs of 6 cases of suspected vaccine-associated measles in Zhongshan City from 2014 to 2015. 450 nucleotide sequences of the C-terminus of measles virus nucleoprotein (N) genes were amplified from the isolates using nested-polymerase chain reaction. Then the genetic relationship, homology of nucleotides, amino acids and amino acid sites of N gene among the deduced sequences, World Health Organization (WHO) reference strains and measles virus vaccine strains in China Shanghai₁₉₁(S₁₉₁) were analyzed. Results Among the 6 detected samples, 2 samples were negative in 450 nucleic acids. 4 samples were detected positive by RT-PCR, and sequence comparison showed that the identities of the nucleotide and the amino acid sequences among 3 viral strains were both 100%, and the homologies of nucleotide and amino acid sequences were both 100% as compared with S₁₉₁ strain. The 3 viral strains and S₁₉₁ strain both belonged to genotype A. Among the detected strains, one belonged to genotype H_1a, and showed 97.7% and 96.6% identity respectively at nucleotide and amino acid sequence levels as compared with Chin9322-H_1a strain. Conclusions Three cases were infected by the measles virus vaccine strain and one was infected with the wild strain.