Zhuge W, Jia F, Adany I, Narayan O, Stephens E B
Marion Merrell Dow Laboratory of Viral Pathogenesis, University of Kansas Medical Center, Kansas City, Kansas, 66160-7240, USA.
Virology. 1997 Jan 6;227(1):24-33. doi: 10.1006/viro.1996.8300.
We examined plasma from macaques infected with three different phenotypes of SIVmac for their ability to neutralize the infectivity of homologous and heterologous virus in lymphocyte (CEMx174 cells or normal rhesus macaque peripheral blood lymphocytes) or normal rhesus macaque macrophage (Mphi) cultures. Similar to previous findings, we observed that some plasmas failed to neutralize or poorly neutralized the infectivity of SIVmac239 and SIVmac251(<1:20 plasma dilution) in lymphocyte cultures. In contrast, when primary rhesus Mphi cultures were used as the indicator cells, the same plasmas neutralized both viruses at high dilutions (1:200 to 1:20,000). Neutralization of virus infectivity by the various plasmas was confirmed by SIV core antigen capture assays. We excluded the possibility that this differential neutralization in Mphi was related to the differences in the ability of the virus strain to replicate in these two cell types by demonstrating that the replication efficiency of SIVmac251 in CEMx174 cells, PBMC, and Mphi cultures was very similar. The role of Fc receptors on the Mphi surface in the clearance of the virus-antibody complexes was also excluded since similar neutralizing results were obtained using whole plasmas, purified IgG antibodies, and purified Fab fragments derived from the IgG fraction of these plasmas. The mechanism of virus neutralization in Mphi does not appear to involve blocking of virus entry into the cells since radiolabeled virus reacted with anti-SIV antibodies was taken up by rhesus Mphi as efficiently as virus reacted with normal antibody. DNA of the neutralized virus was identified in the Mphi cultures, but virus replication, as evidenced by accumulation of viral protein products, was not detectable so long as the antibodies were present in the medium. Removal of the antibodies resulted in a resumption of virus replication in the Mphi. These results indicate that virus infectivity can be efficiently neutralized by antibodies in Mphi cultures by a mechanism that is fundamentally different from that in lymphocyte cultures.
我们检测了感染三种不同表型SIVmac的猕猴的血浆，以评估其在淋巴细胞（CEMx174细胞或正常恒河猴外周血淋巴细胞）或正常恒河猴巨噬细胞（Mphi）培养物中中和同源和异源病毒感染性的能力。与之前的研究结果相似，我们观察到一些血浆在淋巴细胞培养物中无法中和或只能低效中和SIVmac239和SIVmac251的感染性（血浆稀释度<1:20）。相反，当使用原代恒河猴Mphi培养物作为指示细胞时，同样的血浆在高稀释度（1:200至1:20,000）下能够中和这两种病毒。通过SIV核心抗原捕获试验证实了各种血浆对病毒感染性的中和作用。我们通过证明SIVmac251在CEMx174细胞、PBMC和Mphi培养物中的复制效率非常相似，排除了Mphi中这种差异中和与病毒株在这两种细胞类型中复制能力差异有关的可能性。由于使用全血浆、纯化的IgG抗体以及从这些血浆的IgG部分衍生的纯化Fab片段获得了相似的中和结果，Mphi表面Fc受体在病毒 - 抗体复合物清除中的作用也被排除。Mphi中病毒中和的机制似乎不涉及阻止病毒进入细胞，因为与抗SIV抗体反应的放射性标记病毒被恒河猴Mphi摄取的效率与与正常抗体反应的病毒相同。在Mphi培养物中鉴定出了被中和病毒的DNA，但只要培养基中存在抗体，就检测不到病毒复制（以病毒蛋白产物的积累为证据）。去除抗体后，Mphi中的病毒复制得以恢复。这些结果表明，Mphi培养物中的抗体可以通过一种与淋巴细胞培养物中根本不同的机制有效中和病毒感染性。
