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

这个子项目是许多利用资源的研究子项目之一 由NIH/NCRR资助的中心拨款提供。子项目的主要支持 而子项目的主要调查员可能是由其他来源提供的， 包括其它NIH来源。 列出的子项目总成本可能 代表子项目使用的中心基础设施的估计数量， 而不是由NCRR赠款提供给子项目或子项目工作人员的直接资金。 我们最近描述了辅助受体开关在快速进展（RP）R5 SHIVSF 162 P3 N感染的恒河猴，有高病毒复制，和不可检测或微弱和短暂的抗病毒抗体反应。缺乏抗体选择性压力，以及观察到新兴的X4变体是中和敏感的，表明病毒特异性体液免疫应答的缺乏或减弱可能是促进体内辅助受体转换的环境因素。为了测试这种可能性，我们从用SHIVSF 162 P3 N静脉内感染之前的一周开始，每2-3周用50 mg/kg抗CD 20抗体利妥昔单抗治疗4只猕猴，总共输注6次。当通过流式细胞术和免疫组织化学染色分析时，利妥昔单抗治疗成功地耗尽了外周和淋巴CD 20+细胞长达25周，此后在4只治疗猴中的2只中部分至完全恢复。四只处理的猕猴中有三只未能产生可检测的抗SHIV抗体应答，而其余动物的应答延迟。三只血清阴性猕猴进展为疾病，但通过V3序列和嗜性分析均未证明存在X4变体。此外，病毒在这些患病猕猴的早期并没有进化成对sCD 4更敏感。这些结果表明，体液免疫应答的缺乏或减少本身不足以驱动进化病毒的R5至X4转换和中和易感性。

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.