2003～2007年中国风疹病毒基因特征分析

本研究用Vero细胞或Vero/SLAM细胞从我国10个省(直辖市、自治区,下同)2003～2007年风疹暴发和散发病例的咽拭子标本中分离到57株风疹病毒,用RT-PCR方法扩增了57株风疹病毒E1基因1 107个核苷酸的片段,并对该PCR产物进行序列测定和分析.结果提示,在基于WHO基因定型靶序列739个核苷酸片段构建的基因亲缘关系树上,其中55株风疹病毒株属于1E基因型,相对于其他国家的1E基因型,形成一个独立分支;另外2株风疹病毒属于2B基因型.57株风疹病毒大部分核苷酸的突变为无义突变,氨基酸序列高度保守,除了2株风疹病毒在E1蛋白血凝抑制和中和位点区域第212位氨基酸由Thr变为Ser,其他病毒株均无重要抗原位点的改变;所有我国已分离到的1E基因型风疹病毒在E1蛋白第338位氨基酸共享突变位点(Leu338→Phe338),而其他基因型以及其他国家的1E基因型风疹病毒在该位点均未发生突变,提示该氨基酸(Phe338)可能是我国1E基因型风疹病毒所特有.2003～2007年在我国10个省均分离到1E基因型,而2B基因型只在2006年从四川省的越南输入病例中分离到,提示1E为绝对优势基因型,2B基因型为输入基因型.与1979～1984年和1999～2002年我国流行的风疹基因型不同,发生了基因型的更替,近年我国风疹的流行是由1E基因型为主的风疹野病毒的多个传播链引起.

Genetic Characterization of Chinese Rubella Virus Isolates from 2003 to 2007

57 rubella virus strains were isolated using Vero cell line or Vero/SLAM cell line from patients' throat swabs during rubella outbreaks and sporadics in 10 provinces of China from 2003 to 2007. Fragments of 1107 nucleotides of E1 genes of the isolates were amplified by RT-PCR, the PCR products were directly sequenced and analyzed. The phylogenetic analysis based on 739 nucleotides showed that out of 57 Chinese rubella virus strains, 55 belong to a distinguish branch of 1E genotype when comparing with 1E genotype rubella strains from other countries, and the other 2 Chinese rubella virus strains belong to 2B genotype. Most of the nucleotide mutations of 57 rubella viruses were silent mutations, and the amino acid sequences were highly conserved. Except one amino acid change (Thr212 --> Ser212) in two rubella viruses at the hemagglutination inhibition and neutralization epitopes, there had no change found at the important antigenic epitope sites of the other rubella viruses. 1E genotype rubella viruses isolated from 10 provinces of China from 2003 to 2007, and two imported 2B genotype rubella viruses from Vietnam suggested that 1E genotype was the predominant genotype in this period of time. The rubella virus genotypes circulated during 2003 to 2007 were different from that circulating during 1979 to 1984 and 1999 to 2002, the rubella prevailed in recent years was mainly caused by 1E genotype rubella viruses with multi-transmission routes.