PATHOGENIC CONVERSION IN SIV CLONES LACKING NEF GENE

研究表明，SIV的nef基因与SIV的nef基因之间存在一定的同源性。 对于维持高病毒载量和向猿类的进展是重要的 艾滋病（SAIDS）在成年恒河猴。 我们对SIV克隆的分析 Nef基因的大量缺失显示了强大的选择压力 在体内恢复Nef翻译框架并产生疾病。 这一发现引起了对减毒活病毒的严重关注。 基于HIV的缺失克隆的疫苗。 目的减毒活疫苗 猴免疫缺陷病毒（SIV）的病毒疫苗已经被 通过删除病毒辅助基因构建，包括nef， 在恒河猴发病机制中起重要作用。 在以前的研究中， 这样的缺失病毒，以及可复制载体 表达细胞因子γ-干扰素或白细胞介素-2（IL-2）， 在幼年和成年猕猴中似乎相对安全。 结果我们的研究表明，感染病毒的猕猴 在nef（SIVmac 239 D153 nef）中具有大的缺失或具有SIV载体， 其中nef基因的一部分被替换为 IL-2可发展为高病毒载量并发展为致命的猿类艾滋病 （SAIDS）。 从几只患病动物中回收的病毒 一种新的截短形式的Nef蛋白，命名为tNef。 序列 分析显示SIVmac 239 D153 nef和病毒载体的变化 表达IL-2，其恢复翻译框架以产生tNef。 用连续传代的病毒感染的幼年猕猴表达 tNef表现出高病毒载量和免疫缺陷的迹象;然而， 用通过替换nef构建的分子克隆感染猕猴 具有tNef序列的SIVmac 239显示低病毒载量。 因此，在本发明中， tNef的表达可能是必要的，但不是足够的高病毒 负荷和发病机制。 综上所述，这些发现表明 强选择压力恢复致病潜力， 减毒活灵长类慢病毒疫苗。 未来方向 缺乏完整Nef的致病性病毒中病毒基因组的变化 将被定义。 这种变化，涉及另一种病毒基因， 一种病毒调节元件，可以补偿完整Nef的损失， 在体内发挥作用。 将进行体外组织培养研究， 开发新的Nef功能检测方法。 体内评估将 用SIV克隆感染恒河猴， Nef的补偿变化。关键词nef基因，猴艾滋病，SIV 克隆基金NIH Grant AI 38532

Significance Previous studies have shown that the nef gene of SIV is important for maintaining high virus load and progression to simian AIDS (SAIDS) in adult rhesus macaques. Our analysis of SIV clones with large deletions in the Nef gene reveals strong selection pressure to restore the Nef translation frame in vivo and to produce disease. This finding raises serious concerns for live-attenuated viral vaccines based on deletion clones of HIV. Objectives Live-attenuated viral vaccines for simian immunodeficiency virus (SIV) have been constructed by deleting viral accessory genes, including nef, that are important for pathogenesis in rhesus macaques. In previous studies, such deletion viruses, as well as replication-competent vectors expressing the cytokines gamma-interferon or interleukin-2 (IL-2), appeared to be relatively safe in juvenile and adult macaques. Results Our study demonstrated that macaques infected with a virus with a large deletion in nef (SIVmac239D153nef) or with SIV vectors, in which a portion of the nef gene was replaced with the gene for IL-2, can develop high virus loads and progress to fatal simian AIDS (SAIDS). Viruses recovered from several animals with disease produced a novel truncated form of Nef protein, designated tNef. Sequence analysis revealed changes in SIVmac239D153nef and the viral vectors expressing IL-2 that restored the translation frame to produce tNef. Juvenile macaques infected with serially passaged virus expressing tNef exhibited high virus load and signs of immunodeficiency; however, macaques infected with a molecular clone constructed by replacing nef of SIVmac239 with tNef sequences showed low virus load. Thus, expression of tNef may be necessary but not sufficient for high virus load and pathogenesis. Taken together, these findings demonstrate strong selective pressure to restore pathoge nic potential in live-attenuated primate lentivirus vaccines. Future Directions Changes in the viral genome in pathogenic viruses lacking full Nef will be defined. Such changes, involving either another viral gene or a viral regulatory element, may compensate for loss of full Nef function in vivo. In vitro tissue culture studies will be done to develop novel assays for Nef function. In vivo assessments will involve inoculating rhesus macaques with SIV clones containing compensating changes for Nef. KEY WORDS nef gene, simian AIDS, SIV clones FUNDING NIH Grant AI38532