广东登革Ⅰ型病毒株变异性的初步研究

Preliminary study on variation of Guangdong dengue-1 virus strains

目的 通过探讨广东部分登革Ⅰ型病毒的变异性 ,初步了解我国毒株的可能来源。方法 对来自广东省不同年代的登革Ⅰ型毒株LD 2 5 (1985年 )、LD 36 (1991年 )和登革Ⅰ型血清 95 142(1995年 ) ,采用RT PCR方法扩增其E/NS1部分基因片段 ,然后克隆测序。将所测序列中的 2 40bp的片段与国际上已知的多个登革Ⅰ型毒株的相应序列进行比较 ,并以 6 %的核苷酸差异 (divergence)作为分亚型的标准。结果 LD 2 5与LD 36、95 142分别属于两个不同的亚型 ,其中LD 2 5与泰国 1980年毒株及中国台湾 1987年、1988年毒株的同源性高达 (97 1～ 98 8) % ,属于一个亚型。LD 36和 95 142则与菲律宾 (1988年 )、澳大利亚 (1981年 )、印度尼西亚 (1978年 )及瑙鲁 (1974年 )等地的毒株同源性高达(97 5～ 10 0 ) % ,同属于另一个亚型。结论 广东登革Ⅰ型病毒可能不仅是从一个地方传入 ,来源比较复杂。

Objective To study the variation of Guangdong dengue 1 virus strains. Methods Partial nucleotide fragments in E/NS1 gene junction of 2 degue 1 isolates(LD 25, LD 26) and 1 positive sera sample (95 142) of Guangdong province collected in different years, were amplified by RT PCR and sequenced. The 240bp sequences of the above mentioned fragments were compared with those of other well characterized dengue 1 strains. A divergence of 6% between the nucleotide sequences was taken as an indication for dengue virus subtype classification. Results LD 25 and LD 36 or 95 142 may belong to two different subtypes. Dengue strains of LD 25 (1985), Thai(1980) and Taiwan of China(1987,1988) could fall into the same subtype in the light of their sequence homology ranging from 97.1% to 98.8%. The sequence homology among LD 36(1991), 95 142(1995), Philippine(1988) and three other dengue 1 virus strains ranged from 97.5% to 100%, indicating that they belonged to another subtype of dengue virus. Possible source of infection of these dengue virus strains is discussed. Conclusion Guangdong dengue viruses may have not only one source.