Immunization with a novel HIV-1-Tat multiple-peptide conjugate induces effective immune response in mice

We report here a novel, highly immunogenic synthetic, multiple-peptide conjugate comprising functional domains Tat_21–40 and Tat_53–68 from HIV-1 group M plus Tat_9–20 from HIV-1 group O of the HIV-Tat protein (HIV-1-Tat-MPC). Vaccination of mice with HIV-1-Tat-MPC induced an effective immune response to all three functional domains. The anti-HIV-1-Tat-MPC antibodies efficiently inhibited Tat-induced viral activation in monocytes infected with HIV_Ba-L as well as with various clinical HIV-1 isolates, and reduced Tat-mediated cytopathicity in infected cells by 60–75%. Our results indicate that anti-HIV-1-Tat-MPC antibodies inhibit viral pathogenesis, possibly by blocking functional determinants of Tat and disrupting autocrine and paracrine actions of secreted Tat protein. This epitope-specific, synthetic Tat construct may, therefore, provide a subunit AIDS vaccine candidate for inducing an effective immunoprophylaxis response to reduce progression of HIV infection.     

人免疫缺陷病毒1型TAT突变蛋白及反义TAT RNA对TAT反式激活作用的抑制

Ｔａｔ是人免疫缺陷病毒（ＨＩＶ）基因组编码的反式激活因子,突变分析表明它含有几个重要的功能域。为寻找控制ＨＩＶ复制的途径,构建了以ＨＩＶ－１ＬＴＲ（－１５８－＋８０）为启动子的Ｔａｔ ｃＤＮＡ全长反义表达质粒ｐＡＳ－Ｔａｔ,并用已经构建的ＨＩＶ ＬＴＲ－１５８到＋８０为启动子,具有不同突变点的突变Ｔａｔ基因表达质粒,以荧光酶基因为报告基因,共转染Ｊｕｒｋａｔ细胞,结果发现无论是反义Ｔａｔ表达质粒还     

Absence of HIV-1 Evolution in the Gut-Associated Lymphoid Tissue from Patients on Combination Antiviral Therapy Initiated during Primary Infection

Mucosal mononuclear (MMC) CCR5+CD4+ T cells of the gastrointestinal (GI) tract are selectively infected and depleted during acute HIV-1 infection. Despite early initiation of combination antiretroviral therapy (cART), gut-associated lymphoid tissue (GALT) CD4+ T cell depletion and activation persist in the majority of HIV-1 positive individuals studied. This may result from ongoing HIV-1 replication and T-cell activation despite effective cART. We hypothesized that ongoing viral replication in the GI tract during cART would result in measurable viral evolution, with divergent populations emerging over time. Subjects treated during early HIV-1 infection underwent phlebotomy and flexible sigmoidoscopy with biopsies prior to and 15–24 months post initiation of cART. At the 2^nd biopsy, three GALT phenotypes were noted, characterized by high, intermediate and low levels of immune activation. A representative case from each phenotype was analyzed. Each subject had plasma HIV-1 RNA levels <50 copies/ml at 2^nd GI biopsy and CD4+ T cell reconstitution in the peripheral blood. Single genome amplification of full-length HIV-1 envelope was performed for each subject pre- and post-initiation of cART in GALT and PBMC. A total of 280 confirmed single genome sequences (SGS) were analyzed for experimental cases. For each subject, maximum likelihood phylogenetic trees derived from molecular sequence data showed no evidence of evolved forms in the GALT over the study period. During treatment, HIV-1 envelope diversity in GALT-derived SGS did not increase and post-treatment GALT-derived SGS showed no substantial genetic divergence from pre-treatment sequences within transmitted groups. Similar results were obtained from PBMC-derived SGS. Our results reveal that initiation of cART during acute/early HIV-1 infection can result in the interruption of measurable viral evolution in the GALT, suggesting the absence of de-novo rounds of HIV-1 replication in this compartment during suppressive cART.     

HIV-1基因表达的转录调控

高效抗逆转录病毒治疗（HAART）可以有效地抑制人类免疫缺陷病毒Ⅰ型（HIV-1）的复制及血浆病毒载量,延缓发病进程,改善、提高患者的生活质量和存活时间。但是,一旦停止治疗就会导致血浆病毒血症迅速反弹,HIV-1以原病毒的形式在静息记忆CD4⁺T等细胞中的持续存在是清除HIV-1的一个障碍。HIV-1基因转录的激活与阻抑决定了受感染细胞进入产毒性感染或潜伏感染。本文从原病毒整合位置与转录干扰、细胞转录因子与HIV-1启动子相互作用招募RNA聚合酶起始转录、转录的表观遗传调控和反式激活因子Tat及其相关蛋白促进转录延伸等方面探讨了HIV-1原病毒转录调控机制。     

Relationships between the presence of anti-Tat antibody, DNA and RNA viral load

The possible relationships between the intensity of humoral response to full length Tat protein, the amount of proviral DNA reservoir in peripheral blood mononuclear cells and RNA viral load were analyzed in plasma samples obtained from a group of HIV-1 seropositive subjects, who never received any antiretroviral therapy. All HIV-1 patients showed detectable levels of serum IgG to full-length Tat by immunoenzymatic assay. We found a higher percentage of HIV-1 seropositive subjects with low levels of antibody in the presence of barely detectable proviral DNA copies (< or =10 copies/1.5x10(5) PBMCs) and a high anti-Tat antibody response accompanied by variable (from >10(1) to > or =10(3) copies/1.5x10(5) PBMCs) levels of DNA load (p=0.011). Moreover, an inverse relationship between anti-Tat antibody titers and HIV-1 RNA viral load was demonstrated HIV-1 seropositive patients. In HIV-1-infected patients, a strong humoral immune response against HIV-1 transactivating Tat protein, able to down-modulate viral replication in peripheral blood, does not seem to inhibit the number of proviral DNA molecules in peripheral blood mononuclear cells. Even though our data strongly confirm the "positive" role of anti-Tat antibody on viral replication, the persistence of significant amount of DNA viral load in peripheral blood mononuclear cells, despite high level of anti Tat antibody, suggests a more cautious approach to HIV-1 Tat-containing vaccines, able to stimulate an immune specific response to transactivating Tat protein sufficient in inhibiting circulating virus, but not completely efficient in decreasing proviral DNA integration.