SHIV CHALLENGE & IN VIVO PASSAGE

本项目研究了两个SHIV挑战。第一次试验涉及12只先前接种过疫苗的动物。其中6只接种了表达HIV-1LAI gp160的牛痘病毒，随后用牛痘病毒感染的AGMK细胞产生的纯化亚基gp160进行增强。另外6人作为模拟接种疫苗的对照组，单独接种牛痘病毒，并用IFA增强。动物的病毒前攻毒评估显示血清学反应与用各种env制剂免疫的人类相似。用25剂SHIVIIIB组织培养感染剂量（TCID50）攻毒猕猴。通过病毒培养和RNA PCR检测，6只模拟接种的动物呈持续病毒血症。相比之下，在6只接种疫苗的动物中，有一只间歇地恢复了病毒，RNA PCR显示，接种疫苗的动物的病毒水平降低了几个对数。将继续对这些动物进行监测，并将用毒性更强的艾滋病毒重新挑战它们。在第二次攻毒实验中，22只nemestrina分为7个实验疫苗和对照组，也用SHIVIIIB攻毒。结果支持了第一次挑战实验的结果，即牛痘env prime和env boost对挑战提供了最大的保护。两个猕猴，每个对照组一个，经历了自发的CD4下降。为了确定来自这些猕猴的病毒是否变得更具致病性，我们给两只幼稚的动物输了全血。受体猕猴经历了快速且不可逆转的CD4下降。从接受输血者身上回收病毒，并准备了储存品。为了确认这些种群在体内具有传染性，我们给另外两只猕猴接种了1毫升未稀释的病毒。这些动物也表现出CD4耗竭。将在其他猕猴中进行滴度试验，以确定猕猴感染剂量。

Two SHIV challenges have been studied in this project. The first involved 12 previously immunized animals. Six had been vaccinated with vaccinia virus expressing HIV-1LAI gp160 and subsequently boosted with purified subunit gp160 produced by vaccinia virus-infected AGMK cells. The other six served as mock-vaccinated controls, having been given vaccinia virus alone and boosted with IFA. Pre-virus challenge evaluation of the animals revealed serological responses similar to those achieved in humans immunized with various env preparations. The macaques were challenged with 25 tissue culture infectious doses (TCID50) of SHIVIIIB. The six mock-vaccinated animals became persistently viremic by virus culture and RNA PCR. In contrast, virus was recovered intermittently from one of the six vaccinated animals and the RNA PCR revealed virus levels several logs lower in the vaccinated animals. The animals will continue to be monitored and will be rechallenged with a more virulent SHIV. In the second challenge experiment, 22 M. nemestrina divided among 7 experimental vaccine and control groups also were challenged with SHIVIIIB. The results supported those in the first challenge experiment, that vaccinia env prime and env boost afforded the greatest protection against challenge. Two macaques, one from each control group, experienced spontaneous CD4 decline. To determine whether virus from these macaques had become more pathogenic, we gave whole-blood transfusions to two naive animals. The recipient macaques experienced a rapid and irreversible CD4 decline. Virus was recovered from the transfusion recipients and stocks were prepared. To confirm that the stocks were infectious in vivo, we inoculated two additional macaques with 1 ml of undiluted virus. These animals also showed CD4 depletion. The stock will be titered in additional macaques to determine the macaque infectious dose.