浙江省1999-2008年麻疹病毒流行株磷蛋白基因变异研究

Genetic variation of phosphoprotein （P） gene from measles epidemic strains in Zhejiang province

目的 了解浙江省麻疹病毒流行株磷蛋白（P）基因变异规律.方法 采用RT-PCR方法扩增1999-2008年浙江省麻疹病毒流行株P基因全序列,进行序列测定,并与疫苗株Shanghai191及其他麻疹流行株进行比较.结果 1999-2008年浙江省各流行株与疫苗株Shahghai191之间存在59～75个核苷酸的变异（变异率3.9%～4.9%）,导致36～42个氨基酸变异（变异率7.1%～8.3%）,它们在二级结构上也存在一定的差异.P基因系统进化树显示,其基因分型结果与WHO推荐的核蛋白（N）基因分型结果基本一致.P蛋白氨基酸的平均变异率要大于主要抗原基因N和H基因.结论 1999-2008年浙江省麻疹病毒流行株与疫苗株Shanghai191的P基因存在较大差异.

Objective To investigate the genetic characteristics and variation within the phosphoprotein （P） gene of measles epidemic strains circulated in Zhejiang province. Methods The whole sequence of P gene of the epidemic strains related to Zhejiang Measles virus during 1999 to 2008 was amplified, using the RT-PCR Assay. PCR products were sequenced and compared with the sequences of measles vaccine and other epidemic strains. Results Totally, 1524 nucleotides were sequenced from each epidemic strain and 507 amino acids were derived correspondingly. Compared with the vaccine strain, there were 59-75 nucleotides （divergent ratios were 3.9%-4.9%） mutated from the epidemic strains, which were isolated during 1999 to 2008 and causing mutation on 36-42 amino acid （divergent ratios were 7.1%-8.3% ）. Changes were also observed on the secondary structure. The phylogenetic tree, constructed based on the sequences of P gene, was similar to that based on the N gene, recommended by WHO. In addition, the average divergent ratio of P protein was greater than the ratio occurred on the N and H genes. Conclusion The variation within the P gene between the vaccine and epidemic strains circulated in Zhejiang province during 1999 to 2008 was significant.