Kabat D, Kozak S L, Wehrly K, Chesebro B
Department of Biochemistry and Molecular Biology, Oregon Health Sciences University, Portland 97201-3098.
J Virol. 1994 Apr;68(4):2570-7. doi: 10.1128/JVI.68.4.2570-2577.1994.
CD4 is known to be an important receptor for human immunodeficiency virus type 1 (HIV-1) infection of T lymphocytes and macrophages. However, the limiting steps in CD4-dependent HIV-1 infections in vivo and in vitro are poorly understood. To address this issue, we produced a panel of HeLa-CD4 cell clones that express widely different amounts of CD4 and quantitatively analyzed their infection by laboratory-adapted and primary patient HIV-1 isolates. For all HIV-1 isolates, adsorption from the medium onto HeLa-CD4 cells was inefficient and appeared to be limiting for infection in the conditions of our assays. Adsorption of HIV-1 onto CD4-positive peripheral blood mononuclear cells was also inefficient. Moreover, there was a striking difference between laboratory-adapted and primary T-cell-tropic HIV-1 isolates in the infectivity titers detected on different HeLa-CD4 cells. Laboratory-adapted HIV-1 isolates infected all HeLa-CD4 cell clones with equal efficiencies regardless of the levels of CD4, whereas primary HIV-1 isolates infected these clones in direct proportion to cellular CD4 expression. Our interpretation is that for laboratory-adapted isolates, a barrier step that preceeds CD4 encounter was limiting and the subsequent CD4-dependent virus capture process was highly efficient, even at very low cell surface concentrations. In contrast, for primary HIV-1 isolates, the CD4-dependent steps appeared to be much less efficient. We conclude that primary isolates of HIV-1 infect inefficiently following contact with surfaces of CD4-positive cells, and we propose that this confers a selective disadvantage during passage in rapidly dividing leukemia cell lines. Conversely, in vivo selective pressure appears to favor HIV-1 strains that require large amounts of CD4 for infection.
已知CD4是人类免疫缺陷病毒1型（HIV-1）感染T淋巴细胞和巨噬细胞的重要受体。然而，体内和体外CD4依赖性HIV-1感染的限制步骤尚不清楚。为了解决这个问题，我们构建了一组HeLa-CD4细胞克隆，它们表达的CD4量差异很大，并通过实验室适应株和患者来源的HIV-1原代分离株对其感染情况进行了定量分析。对于所有HIV-1分离株，病毒从培养基吸附到HeLa-CD4细胞上的效率很低，在我们的实验条件下似乎是感染的限制因素。HIV-1吸附到CD4阳性外周血单核细胞上的效率也很低。此外，实验室适应株和T细胞嗜性HIV-1原代分离株在不同HeLa-CD4细胞上检测到的感染性滴度存在显著差异。实验室适应的HIV-1分离株以相同效率感染所有HeLa-CD4细胞克隆，而与细胞CD4表达水平无关，而HIV-1原代分离株感染这些克隆的效率与细胞CD4表达成正比。我们的解释是，对于实验室适应株，在与CD4接触之前的一个障碍步骤是限制因素，随后的CD4依赖性病毒捕获过程非常高效，即使在细胞表面浓度非常低的情况下也是如此。相比之下，对于HIV-1原代分离株，CD4依赖性步骤似乎效率要低得多。我们得出结论，HIV-1原代分离株在与CD4阳性细胞表面接触后感染效率低下，我们认为这在快速分裂的白血病细胞系传代过程中赋予了选择性劣势。相反，体内选择压力似乎有利于需要大量CD4才能感染的HIV-1毒株。
