新疆地区2003-2004年麻疹野病毒分离株基因特征分析

Genetic characterization of wild-type measles viruses isolated in Xinjiang in 2003 and 2004

目的了解新疆地区流行的麻疹野病毒基因型和亚型特征。方法对2003-2004年用健康产婴儿脐带血单个核细胞分离的麻疹野病毒进行分子流行病学分析。采用逆转录-聚合酶链反应对麻疹病毒N基因C末端676个核苷酸片段进行扩增,并对扩增产物进行核苷酸序列测定。通过分析C末端450个核苷酸序列构建基因亲缘关系树,并分析毒株变异情况。结果2003年和2004年各分离麻疹病毒3株(XJ03-26、XJ03-27、XJ03.74、XJ04-146、XJ04-150、XJ04-152),除XJ03-26株与沪191株核苷酸差异<1%,属疫苗相关株A基因型外,其余5株均为H1基因型。其中XJ03-27、XJ03-74、XJ04-150和XJ04-152与H1a参考株China9322的核苷酸差异为0.5%～1.6%,同属于H1a亚型;XJ04-146与H1b参考株China9475的核苷酸同源性为98.7%,属于H1b亚型。4株H1a毒株分属两组(即XJ03-27与XJ04-150,XJ03-74与XJ04-152),每组内毒株N基因碳末端450个核苷酸序列几近相同无差异,但两组间毒株却存在较大变异,核苷酸差异达6.1%(27个核苷酸差异)。结论新疆地区2003-2004年流行的麻疹病毒以H1a亚型为主,亦存在H1b亚型。

Objective To study the genetic characterization of wild-type measles viruses isolated in Xinjiangin 2003 and 2004. Methods Peripheral blood mononuclear cells （PBMC） from 19 suspected measles cases collected between June 2003 and April 2004 were used to isolate measles virus by cocultivation with phytohemagglutinin（PHA）-stimulated cord blood mononuclear cells （CBMC）. For positive samples, 676 nucleotides of the C-terminus of the nucleoprotein （N） gene of the measles virus genome were amplified by reverse transcription-polymerase chain reaction and then sequenced. These sequences were compared with those of other measles reference strains available in GenBank or measles isolates elsewhere in China using BLAST searches and phylogenetic analyses. Results 6 measles virus strains were isolated with 3 strains （XJ03-26,XJ03-27,XJ03-74） from 2003 and 3 （XJ04-146,XJ04-150,XJ04-152） from 2004. The strain XJ03-26,differed from the Chinese measles vaccine strain S-191 （genotype A） by less than 1% at nucleotide level, and therefore appeared a vaccine-associated strain. The other 5 strains as XJ03-27, XJ03-74,XJ04-146,XJ04-150 and XJ04-152 were proved to be genotype H1 strains, among which XJ03- 27, XJ03-74, XJ04-150 and XJ04-152, showing their nucleotide diversity were varied from 0.5 % to 1.6 %, when compared to the Hla reference strain China9322, and identified as Hla strains. XJ04-146 showed a nucleotide similarity of 98.7 % when compared to Hlb reference strain China9475, and was identified as Hlb strain. Additionally,we found that there were two sets of strain （XJ03-27 and XJ04-150; XJ03-74 and XJ04-152）, with almost identical nucleotide sequences, circulating in 2003 and 2004 and both having more nucleotide variability （ up to 6.1%, 27 nucleotides）. Conclusion Genotype H1 measles virus had been proven to have been circulated in Xinjiang, China during 2003 and 2004. Hla was the predominant epidemic strain while Hlb strain stood the next.