R5 SHIV/MACAQUE MODEL FOR THE EVALUATION OF T AND B CELL-BASED HIV-1 VACCINE

这个子项目是利用资源的许多研究子项目之一。 由NIH/NCRR资助的中心拨款提供。对子项目的主要支持 子项目的首席调查员可能是由其他来源提供的， 包括美国国立卫生研究院的其他来源。为子项目列出的总成本可能 表示该子项目使用的中心基础设施的估计数量， 不是由NCRR赠款提供给次级项目或次级项目工作人员的直接资金。 我们最近描述了快速进展子(RP)R5 SHIVSF162P3N感染猕猴的辅受体开关，这些猕猴具有高病毒复制，以及无法检测到或弱而短暂的抗病毒抗体反应。抗体选择性压力的缺乏，以及新出现的X4变异体对中和敏感的观察表明，病毒特异性体液免疫反应的缺失或减弱可能是促进体内辅受体切换的环境因素。为了测试这种可能性，我们从静脉感染SHIVSF162P3N的前一周开始，每隔2-3周给4只猕猴注射50 mg/kg的抗CD20抗体利妥昔单抗，总共注射6次。通过流式细胞仪和免疫组织化学染色分析，利妥昔单抗治疗成功地耗尽外周和淋巴CD20+细胞长达25周，此后在四只接受治疗的猴子中有两只部分恢复到完全恢复。在四只接受治疗的猕猴中，有三只未能产生可检测到的抗希沃克病毒抗体反应，而其余动物的反应被推迟。这3只血清阴性猕猴均进展为疾病，但通过V3序列和趋向性分析，没有一只猕猴出现X4变异。此外，在这些患病猕猴中，病毒并没有在早期进化为对sCD4更敏感。这些结果表明，体液免疫反应本身的缺失或减弱不足以驱动进化中的病毒从R5到X4的转换和中和敏感性。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. We recently described coreceptor switch in rapid progressor (RP) R5 SHIVSF162P3N-infected rhesus macaques that had high virus replication, and undetectable or weak and transient antiviral antibody response. The lack of antibody selective pressure, together with the observation that the emerging X4 variants were neutralization sensitive, suggested that the absence or weakening of virus-specific humoral immune response could be an environmental factor fostering coreceptor switching in vivo. To test this possibility, we treated four macaques with 50 mg/kg of the anti-CD20 antibody rituximab every 2-3 weeks starting from the week prior to intravenous infection with SHIVSF162P3N for a total of six infusions. Rituximab treatment successfully depleted peripheral and lymphoid CD20+ cells for up to 25 weeks when analyzed by flow cytometry and immunohistochemical staining, with partial to full recovery in two of the four treated monkeys thereafter. Three of the four treated macaques failed to mount a detectable anti-SHIV antibody response while response was delayed in the remaining animal. The three seronegative macaques progressed to disease, but in none of them could be demonstrated the presence of X4 variants by V3 sequence and tropism analyses. Furthermore, viruses did not evolve early in these diseased macaques to be more sCD4-sensitive. These results demonstrate that the absence or diminution of humoral immune responses by itself is insufficient to drive R5-to-X4 switch and neutralization susceptibility of the evolving viruses.