SHIV CHALLENGE & IN VIVO PASSAGE

在这个项目中研究了两个SIV挑战。第一起涉及12只先前免疫的动物。其中6人接种了表达HIV-1LAI gp160的痘苗病毒，随后用痘苗病毒感染的AGMK细胞产生的纯化的gp160亚基加强免疫。其他6人作为模拟疫苗对照组，单独接种牛痘病毒，并用IFA加强免疫。对动物的病毒前挑战评估显示，血清学反应与用各种环状病毒制剂免疫的人类相似。用25个组织培养感染剂量(TCID50)的SHIVIIIB攻击猕猴。通过病毒培养和RNA聚合酶链式反应，6只模拟疫苗接种的动物成为持续的病毒携带者。相比之下，从六只接种疫苗的动物中的一只身上间歇性地恢复了病毒，RNA聚合酶链式反应显示，接种疫苗的动物的病毒水平低了几个对数。这些动物将继续受到监测，并将再次受到更具致命性的希夫病毒的挑战。在第二次攻击实验中，分成7个实验疫苗组和对照组的22个新城疫霉菌也被用SHIVIIIB攻击。这些结果支持了第一个挑战实验中的结论，即牛痘病毒env Prime和env Boost对挑战提供了最大的保护。两只猕猴，每一对照组各一只，经历了自发的CD4下降。为了确定这些猕猴身上的病毒是否变得更具致病性，我们给两只幼小的动物输了全血。受体猕猴经历了快速且不可逆转的CD4下降。从受血者身上回收病毒，并准备好原料。为了确认这些种群在体内具有传染性，我们向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CD_4的耗尽。该种群将在更多的猕猴中进行滴定，以确定猕猴的感染剂量。

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.