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目的分析1例接种麻疹减毒活疫苗第9天出现麻疹样症状病例的麻疹病毒基因特征,以确定是麻疹疫苗相关病例还是偶合麻疹野病毒感染。方法提取该病例咽拭子标本核酸,采用RT-PCR法扩增麻疹病毒核蛋白(Nucleoprotein,NP)基因羧基末端450个核苷酸片段后测序,分析其与全球24个基因型麻疹野病毒代表株、中国疫苗株(Shanghai-191)基因的亲缘关系以及核苷酸、氨基酸序列同源性。结果该病例感染的病毒属于H1a基因亚型麻疹野病毒。与中国H1基因型麻疹野病毒流行株代表株核苷酸和氨基酸序列的同源性较高,分别为97.5%～99.5%和96.6%,而与麻疹病毒中国疫苗株(Shanghai-191)核苷酸和氨基酸序列同源性较低,分别仅为91.2%和86.7%。结论该例接种麻疹减毒活疫苗后出现麻疹样症状的病例为偶合H1基因型麻疹野病毒感染所致,非麻疹疫苗相关病例。
Objective To analyze the genetic characteristics of measles virus in measles-like cases on the 9th day of live attenuated measles vaccine in order to determine whether it is measles-related or coupled with wild-type measles virus infection. Methods Nucleic acid of throat swab specimens was extracted from this case. Nucleotide (450 bp) fragment of nucleoprotein (NP) gene of measles virus was amplified by RT-PCR and sequenced. The results were compared with those of 24 genotypes Strain and Chinese vaccine strain (Shanghai-191), as well as nucleotide and amino acid sequence homology. Results The case-infected virus belonged to the H1a subtype measles wild virus. The nucleotide and amino acid sequences of the representative strains of wild-type H1NG genotype were 97.5% -99.5% and 96.6%, respectively, but not identical to those of Shanghai-191 nucleoside The homologies of acid and amino acid sequences were low, which were only 91.2% and 86.7% respectively. Conclusions This case of measles-like measles-like measles-attenuated live vaccine was associated with a wild type H1N1 measles virus infection and non-measles vaccine-related cases.