云南瑞丽人免疫缺陷病毒感染者gp120基因C2-V3区的序列测定和亚型分析

Subtype and sequence analysis of the C2-V3 region of gp120 genes among human immunodeficiency virus infected IDUs in Ruili epidemic area of Yunnan Province of China

经套式聚合酶链反应（ｎｅｓｔｅｄ－ＰＣＲ）对１７份１９９５年初采集于云南瑞丽市人免疫缺陷病毒１型（ＨＩＶ－１）阳性静脉吸毒者外周血单核细胞（ＰＢＭＣｓ）的核酸样品进行扩增，从１７份样品中获得了ＨＩＶ－１膜蛋白（ｅｎｖ）基因的核酸片段，并对其Ｃ２－Ｖ３及邻区４５０个核苷酸序列进行了测定和分析。结果表明，１７份样品中存在Ｂ和Ｃ两种亚型的ＨＩＶ－１毒株序列，其亚型内的基因离散率分别为５８％和２２％，与Ａ－Ｅ参考亚型及部分Ｂ和Ｃ亚型代表株序列相比较，属Ｂ亚型的１２个毒株与包括泰国、缅甸及云南瑞丽代表株ｙｎ２８９在内的Ｂ亚型毒株序列十分接近，基因离散率在４４％～４９％的范围内；属Ｃ亚型的５个毒株则与主要代表印度Ｃ亚型毒株的共享序列ｃｃｏｎ及瑞丽Ｃ亚型代表毒株ｙｎ２７２十分相似，其基因离散率均为１９％。以上数据进一步确认我们的结论，即ＨＩＶ－１在瑞丽的流行以Ｂ亚型毒株为主、Ｃ亚型的传人和流行时间较短。对Ｂ亚型毒株Ｖ３环序列的分析还发现，位于Ｖ３环顶端的四肽序中ＧＰＧＱ占５０％，ＧＰＧＲ则仅占２５％，且编码其精氨酸（Ｒ）的密码子均为ＣＧＡ而不是ＡＧＡ。此结果与我们根据早期瑞丽ＨＩＶ－１毒株序列研究结果得出的推测?

DNA fragments of HIV-1 env gene were amplified by nested-PCR from 17 uncultured peripheral blood mononuclear cells (PBMCs) obtained from HIV-1 seropositive intravenous drug users (IDUs) in Ruili city of Yunnan Province. The C2-V3 region (about 450 bp) of them were sequenced. Sequence analysis showed that there exists two HIV-1 subtypes, B and C, with 5.8% and 2.2% gene divergence inside each subtype. The 12 subtype B strains, were closely related to those found in Thailand, Myanma and Ruili city of Yunnan, and the nucleotide sequence divergence between them ranged from 4.4% to 4.9%; meanwhile, the 5 subtype C strains were most close to those found in lndia as well as Ruili city, all with a genetic distance of 1.9%. The small divergence among Ruili HIV-1 subtype C strains suggests a recent epidemic. The analysis of V3 loop amino sequence of 12 subtype B HIV-1 reveals that V3-tip motif of 6 samples (50%) is GPGQ and that of 3 samples (25%) is GPGR. In addition, the codon of arginine (R) of all the strains is CGA instead of AGA. This result is in accordance with our previous hypothesis that there is a drift in vivo from GPGR to GPGQ motif on the tip of V3-loop of HIV-1 subtype B strain in this area with the elapse of time.