Shioda T, Oka S, Ida S, Nokihara K, Toriyoshi H, Mori S, Takebe Y, Kimura S, Shimada K, Nagai Y
Department of Viral Infection, University of Tokyo, Japan.
J Virol. 1994 Dec;68(12):7689-96. doi: 10.1128/JVI.68.12.7689-7696.1994.
Human immunodeficiency virus type 1 circulates in vivo as a mixture of heterologous populations (quasispecies). We previously analyzed the quasispecies of the third hypervariable region (V3) in the viral envelope glycoprotein gp120 in an infected individual and found that the species with a basic amino acid substitution (lysine for aspartic acid) at a particular position evolved and became a distinct population within a short period, followed by progression to the typical immunodeficiency stage (S. Oka et al., AIDS Res. Hum. Retroviruses 10:271-277, 1994). In the present study, we examined the biological significance of this amino acid substitution by constructing recombinant viruses with specific point mutations and comparing their replication capabilities in different cell types. The results demonstrated that the single basic amino acid substitution was sufficient to render a virus fully capable of replicating in human T-cell lines under certain conditions. With an acidic amino acid at the position, the virus grew much less fast or did not grow at all in the T-cell lines. Viral neutralization assay and peptide enzyme-linked immunosorbent assays further showed that this amino acid substitution resulted in different recognition by several of the serum specimens from human immunodeficiency virus type 1-infected individuals and thus could alter the antigenic structure. An additional finding worthy of note was that at the terminal stage, the proviral sequences of peripheral blood mononuclear cells and the viral isolates from them were without exception of the late type with the basic amino acid substitution, whereas the early sequence without the substitution was retained as a major subset in the spleen. These results support the notion that basic amino acid substitutions in V3 are a strong predictor of virus tropism and may be relevant to disease progression.
1型人类免疫缺陷病毒在体内以异源群体（准种）的混合物形式传播。我们之前分析了一名感染者病毒包膜糖蛋白gp120中第三个高变区（V3）的准种，发现特定位置发生碱性氨基酸替代（天冬氨酸被赖氨酸替代）的毒株在短时间内进化并成为一个独特的群体，随后发展到典型的免疫缺陷阶段（S. Oka等人，《艾滋病研究与人类逆转录病毒》10:271 - 277，1994年）。在本研究中，我们通过构建具有特定点突变的重组病毒并比较它们在不同细胞类型中的复制能力，研究了这种氨基酸替代的生物学意义。结果表明，单一的碱性氨基酸替代足以使病毒在某些条件下完全能够在人T细胞系中复制。该位置为酸性氨基酸时，病毒在T细胞系中生长得慢得多或根本不生长。病毒中和试验和肽酶联免疫吸附试验进一步表明，这种氨基酸替代导致来自1型人类免疫缺陷病毒感染者的几份血清标本有不同的识别，从而可能改变抗原结构。另一个值得注意的发现是，在终末期，外周血单核细胞的前病毒序列及其分离出的病毒无一例外都是具有碱性氨基酸替代的晚期类型，而没有这种替代的早期序列则作为主要亚群保留在脾脏中。这些结果支持了V3区碱性氨基酸替代是病毒嗜性的有力预测指标且可能与疾病进展相关的观点。
