HIV-1辅受体的配体细胞内双表达对病毒感染的阻断作用

目的　观察Ⅰ型人免疫缺陷病毒 (HIV 1)辅受体的配体———RANTES和SDF 1α双表达于人淋巴细胞对各种嗜性HIV 1毒株感染的阻断作用。方法　用 pLNCX R K S K重组逆转录病毒液感染原代人外周血淋巴细胞 (PBLs) ,抗神经生长因子受体 (NGFR) 免疫磁珠法分离转化成功的PBLs,流式细胞仪检测筛选效率 ;HIV 1M嗜性、T嗜性和双嗜性毒株攻击转化PBLs ,检测HIV 1逆转录酶活性和 p2 4抗原分泌 ,以观察抗HIV 1感染的作用 ;同时进行转化PBLs表面CD3、CD4、CCR2、CCR5和CXCR4表达及破伤风毒素刺激后3 H 胸苷 (thymidine)掺入量检测 ,观察HIV 1辅受体配体的双表达对人PBLs正常生物学功能的影响。结果　抗 NGFR 免疫磁珠法获得了转化成功的PBLs,流式细胞仪检测发现pLNCX R K S K转染组 92 %以上的PBLs鼠抗NGFR标记物为阳性 ;HIV 1M嗜性、T嗜性和双嗜性毒株攻击后 ,pLNCX R K S K转化PBLs可以见到明显的逆转录酶活性和 p2 4抗原分泌抑制 ,并且在感染后第 12～ 2 0天时抑制作用最强 ;pLNCX R K S K转化PBLs表面CD3、CD4和CCR2表达水平无明显变化 ,而CCR5和CXCR4表达水平降低 ;破伤风毒素刺激后的转化PBLs仍具有主动增殖的能力。结论　HIV 1辅受体的配体通过在人PBLs内双表达 ,使HIV 1两类主要辅受体表型剔除 ,基本阻断了     

KAI1基因转染的胰腺癌细胞系的建立

目的转染pCMV—KAI1重组质粒入人胰腺癌细胞株MiaPacaⅡ和Panc1，观察KAⅡ基因的表达，为进行KAI1基因在胰腺癌中抗转移作用的有关研究提供实验用靶细胞，并为今后利用KAI1基因治疗胰腺癌提供实验和理论依据。方法采用Western blot方法从7种胰腺癌细胞中筛选出无KAI1表达的MiaPacaⅡ和Panc1细胞株，通过脂质体转染法将pCMV—KAI1重组质粒转染到MiaPacaⅡ和Panc1中，经G418筛选4周，获得单克隆细胞系，应用Western blot、免疫荧光及免疫细胞化学方法检测转染细胞系KAI1蛋白的表达。结果获得了稳定表达KAI1基因的MiaPacaⅡ和Panc1胰腺癌细胞克隆；经Western blot分析显示转染后的胰腺癌细胞株MiaPacaⅡ与Panc1有明确的分子质量为29100KAI1蛋白表达，而未转染细胞无KAI1蛋白表达；免疫荧光显示，转染的胰腺癌细胞质中可见明显的荧光，而无转染的母细胞无荧光；免疫细胞化学检测显示，无转染的细胞呈阴性反应，转染的细胞呈中到强度的阳性反应。结论pCMV—KAI1重组质粒经转染人人胰腺癌细胞株MiaPacaⅡ和Panc1后可表达KAI1蛋白，从而建立了KAIl蛋白表达的MiaPacaⅡ和Panc1细胞系。     

人血凝素样氧化型低密度脂蛋白受体1双顺反子表达载体的构建及其在293T细胞中的表达

目的尝试构建人血凝素样氧化型低密度脂蛋白受体1(LOX-1)基因双顺反子表达载体并检测其在293T细胞中的表达情况和生物学活性,为深入探讨LOX-1在动脉粥样硬化中的作用和以LOX-1为靶点建立干预机制治疗动脉粥样硬化奠定基础。方法首先根据Primer5.0软件设计引物,采用聚合酶链反应法以LOX-1 c DNA片段为模板扩增LOX-1基因完整编码区,克隆至T载体,经测序成功后亚克隆到双顺反子真核表达载体p IRES2-Ac GFP1-Nuc。利用脂质体转染法将双顺反子重组表达质粒转染至293T细胞,倒置荧光显微镜检测质粒转染情况。采用逆转录聚合酶链反应和免疫印迹法鉴定LOX-1基因在核酸和蛋白水平的表达,采用激光共聚焦检测LOX-1基因在293T细胞膜上的表达,激光共聚焦和流式细胞术检测表达在293T细胞膜上的LOX-1结合氧化型低密度脂蛋白(ox-LDL)的生物学活性。结果成功构建p IRES2-LOX-1双顺反子重组表达载体,将其转染293T细胞后,观察到绿色荧光蛋白基因的表达,初步表明LOX-1基因转染至293T细胞。进一步分子水平鉴定结果表明LOX-1基因在293T细胞核酸和蛋白水平均得到表达,激光共聚焦结果证明LOX-1基因在293T细胞膜上表达。最后激光共聚焦和流式细胞术结果证实表达在293T细胞膜上的人LOX-1基因可以结合氧化型低密度脂蛋白。结论成功构建人LOX-1基因双顺反子表达载体,在此基础上证明其在293T细胞膜上得到表达,并且具有结合ox-LDL的生物学活性,为后续体外研究其在动脉粥样硬化中的作用以及以此为靶点建立干预机制奠定了基础。     

CXC趋化因子配体8对宫颈癌细胞增殖与迁移的影响及作用机制

目的探讨外源性及过表达CXC趋化因子配体(CXCL)8对HeLa宫颈癌细胞增殖与迁移的影响及作用机制。方法利用基因转染构建过表达CXCL8的HeLa宫颈癌细胞,应用酶联免疫吸附试验(ELISA)鉴定转染效率;CCK8和Transwell实验研究外源性及过表达CXCL8对HeLa增殖与迁移的影响;蛋白免疫印迹实验检测过表达CXCL8对HeLa细胞蛋白激酶B(AKT)蛋白表达的影响。结果过表达细胞株细胞培养上清液中CXCL8蛋白表达明显高于对照细胞株;不同浓度的外源性CXCL8及过表达CXCL8可显著促进HeLa细胞增殖和迁移能力;HeLa细胞过表达CXCL8可显著上调AKT蛋白表达。结论CXCL8可经磷脂酰肌醇3-激酶(PI3K)/AKT途径而参与宫颈癌恶性发展过程。     

刚地弓形虫ROP10-ROP18真核表达载体的构建与鉴定

目的构建刚地弓形虫棒状体蛋白10(ROP10)、棒状体蛋白18(ROP18)复合基因真核表达载体pVAXDROP10-ROP18,并在HeLa细胞内表达目的蛋白。方法设计ROP10、ROP18基因特异引物,采用RT-PCR扩增ROP10、ROP18基因并测序,将ROP10和ROP18基因分别定向插入双启动子真核表达载体pVAXD的多克隆位点中,构建单价质粒pVAXD-ROP10和pVAXD-ROP18,然后将ROP18基因插入pVAXD-ROP10中构建双启动子真核表达载体pVAXD-ROP10-ROP18。经PCR和双酶切验证后将pVAXD-ROP10-ROP18转染至HeLa细胞内,提取细胞总RNA并逆转录为cDNA,以此为模板分别进行ROP10基因和ROP18基因的RT-PCR鉴定;采用间接免疫荧光试验(IFA)检验ROP10和ROP18蛋白表达情况。结果成功克隆ROP10、ROP18基因片段并构建了重组质粒pVAXDROP10-ROP18,测序、双酶切和PCR验证重组质粒构建正确。分别将3种重组质粒转染至HeLa细胞后经RT-PCR鉴定,pVAXD-ROP10-ROP18组可同时扩增出1 761bp(ROP10基因)和1 665bp(ROP18基因)2个片段,而pVAXDROP10组和pVAXD-ROP18组分别扩增出1 761bp和1 665bp的目的片段;IFA显示pVAXD-ROP10组和pVAXDROP18组均有绿色荧光,即分别表达ROP10和ROP18蛋白。结论成功构建重组质粒pVAXD-ROP10-ROP18、pVAXD-ROP10和pVAXD-ROP18质粒可在真核细胞中分别表达ROP10和ROP18两种蛋白。     

刚地弓形虫ROP10-ROP18真核表达载体的构建与鉴定北大核心CSCD

目的构建刚地弓形虫棒状体蛋白10(ROP10)、棒状体蛋白18(ROP18)复合基因真核表达载体pVAXDROP10-ROP18,并在HeLa细胞内表达目的蛋白。方法设计ROP10、ROP18基因特异引物,采用RT-PCR扩增ROP10、ROP18基因并测序,将ROP10和ROP18基因分别定向插入双启动子真核表达载体pVAXD的多克隆位点中,构建单价质粒pVAXD-ROP10和pVAXD-ROP18,然后将ROP18基因插入pVAXD-ROP10中构建双启动子真核表达载体pVAXD-ROP10-ROP18。经PCR和双酶切验证后将pVAXD-ROP10-ROP18转染至HeLa细胞内,提取细胞总RNA并逆转录为cDNA,以此为模板分别进行ROP10基因和ROP18基因的RT-PCR鉴定;采用间接免疫荧光试验(IFA)检验ROP10和ROP18蛋白表达情况。结果成功克隆ROP10、ROP18基因片段并构建了重组质粒pVAXDROP10-ROP18,测序、双酶切和PCR验证重组质粒构建正确。分别将3种重组质粒转染至HeLa细胞后经RT-PCR鉴定,pVAXD-ROP10-ROP18组可同时扩增出1 761bp(ROP10基因)和1 665bp(ROP18基因)2个片段,而pVAXDROP10组和pVAXD-ROP18组分别扩增出1 761bp和1 665bp的目的片段;IFA显示pVAXD-ROP10组和pVAXDROP18组均有绿色荧光,即分别表达ROP10和ROP18蛋白。结论成功构建重组质粒pVAXD-ROP10-ROP18、pVAXD-ROP10和pVAXD-ROP18质粒可在真核细胞中分别表达ROP10和ROP18两种蛋白。     

组织因子表达影响阿霉素对人神经母细胞瘤细胞毒性的研究

目的：研究组织因子（TF）表达对阿霉素在人神经母细胞瘤细胞系中细胞毒性的影响。方法：以Western Blotting检测TF表达。分子生物学方法构建TFsiRNA—pSUPER表达载体，以脂质体介导进行基因转染。以WST法检测阿霉素细胞毒性。结果：①人神经母细胞瘤细胞系SK—N—MC高表达TF；②所构建的TFsiRNA—pSUPER表达载体转染SK-N—MC细胞后，呈剂量依赖性降低TF表达水平；③转染TFsiRNA-pSUPER的SK—N—MC细胞与转染pSUPER质粒的对照细胞分别以不同浓度的阿霉素处理后，前者与后者相比存活细胞数显著降低。结论：以siRNA特异性下调人神经母细胞瘤细胞SK—N—MC中的TF表达，可增强阿霉素的细胞毒性。TF的异常高表达有可能增强肿瘤细胞对化疗药物的耐受性，籍此影响疾病预后。     

乙型肝炎病毒X蛋白基因型特异性功能差异

目的研究B、C基因型乙型肝炎病毒X蛋白（HBx）功能差异。方法B、C基因型乙型肝炎病毒X基因真核表达载体（分别为pcDNA3．1－XB及pcDNA3．1－XC）及空白载体pcDNA3．1／Hygro（－）以脂质体2000分别转染Chang细胞，转染细胞2d后以流式细胞仪检测凋亡率；转染细胞以潮霉素筛选，14d后形成的抗性细胞集落以冷甲醇固定、Gimsa染色并计数；各载体与指示载体pCMVβ共转染细胞，转染2d后裂解细胞并检测胞内β-半乳糖苷酶的活性。所有数据均以配对t检验进行分析。结果各载体转染Chang细胞后细胞的凋亡率为pcDNA3．1-XC〉pcDNA3．1-XB〉pcDNA3．1／Hygro（-），形成的抗潮霉素细胞集落数为pcDNA3．1／Hygro（-）〉pcDNA3．1-XB〉pcDNA3．1-XC，细胞内β-半乳糖苷酶活性为pcDNA3．1-XB＋pCMVβ〉pcDNA3．1-XC＋pCMVβ〉pcDNA3．1／Hygro（-）＋pCMVβ。结论B基因型HBx反式激活能力高于C基因型HBx，而抗细胞增殖及致细胞凋亡能力都低于C基因型HBx，HBx这些功能差异可能与R、C基因型乙型肝炎病毒致病性差异有关。     

汉坦病毒汉城型浙37株G1、G2包膜糖蛋白基因重组体的构建及在真核细胞中的表达

目的：构建汉坦病毒浙37（Z37）株包膜糖蛋白基因G1、G2真核表达质粒，并在真核细胞中表达。方法：根据Z37M基因序列设计6条引物，分别以质粒pGEMZ37,pCUMZ37为模板，通过聚合酶链反应（PCR）获得G1及G2片段。将G1、G2片段经BamHⅠ、XhoⅠ双酶切片插入至真核表达载体pcDNA3.1( ），经酶切鉴定，并测序证实。以磷酸钙沉淀法分别将重组质粒转染COS－7细胞，用间接免疫荧光法（IFA）检测瞬时表达的蛋白。结果：获得分别含有编码汉坦病毒（HV）Z37株包膜糖蛋白G1、G2基因的重组质粒pcDNA3.1-g1,pcDNA3.1-G2；在转染的COS－7细胞内，用IFA可检测到细胞内有特异性荧光。结论：成功地构建了HV Z37株包膜糖蛋白G1、G2基因真核表达载体，并可在COS－7细胞中瞬时表达。     

Molecular mapping of epitopes for interaction of HIV-1 as well as natural ligands with the chemokine receptors, CCR5 and CXCR4

OBJECTIVE: Mapping coreceptor epitopes used by the prototypic R5 and X4 strains, HIV-1BaL and HIV-1IIIB, in comparison with epitopes involved in the activation and signaling induced by the natural ligands, RANTES and SDF-1beta. DESIGN: Receptor hybrids between CCR5 and CXCR4 were constructed. METHODS: Using single-overlap and extension PCR, increasing portions of CCR5 were replaced with corresponding parts of CXCR4. Viral interaction with these constructs was monitored in infection experiments using stably transfected cell lines, and ligand-induced activation of cells transiently expressing the constructs was measured in terms of calcium fluxes. RESULTS: SDF-1beta required an essentially complete CXCR4, whereas RANTES demanded both the N terminus and the first two extracellular loops of CCR5. HIV-1 infection experiments emphasized the importance of the CCR5 N terminus for infection with HIV-1BaL, whereas HIV-1IIIB was less demanding in its use of CXCR4. CONCLUSION: This study, for the first time monitoring CCR5 and CXCR4 ligand activation and HIV-1 interaction concomitantly, indicates that ligands and virus use different receptor epitopes which, in turn, vary between the two receptors. One particular chimera (FC-4b), having its junctional region close to the conserved cysteine in ECL2, functioned as coreceptor for both HIV-1BaL and HIV-1IIIB, but was not activated with RANTES or SDF-1beta. The results provide a basis for tailoring drugs that block viral entry through the two major coreceptors without interfering with their physiological function.     

Short communication: Influence of active tuberculosis on chemokine and chemokine receptor expression in HIV-infected persons

Tuberculosis (TB) is the major opportunistic infection of HIV-1-infected patients in developing countries. Concurrent infection with TB results in immune cells having enhanced susceptibility to HIV-1 infection, which facilitates entry and replication of the virus. Cumulative data from earlier studies indicate that TB provides a milieu of continuous cellular activation and irregularities in cytokine and chemokine circuits that favor viral replication and disease progression. To better understand the interaction of the host with HIV-1 during active tuberculosis, we investigated in vivo expression of the HIV-1 coreceptors, CCR5 and CXCR4, and circulating levels of the inhibitory beta-chemokines, macrophage inflammatory protein-1-alpha (MIP-1alpha), macrophage inflammatory protein-1-beta (MIP-1beta), and regulated upon activation T cell expressed and secreted (RANTES), in HIV-positive individuals with and without active pulmonary tuberculosis. We found a significant decrease from normal in the fraction of CD4+ T cells expressing CCR5 and CXCR4 in individuals infected with HIV. However, CCR5 and CXCR4 expression did not differ significantly between HIV patients with and without tuberculosis. Higher amounts of MIP-1alpha, MIP-1beta, and RANTES were detected in plasma of HIV-1-positive individuals, particularly those with dual infection, although the increase was not found to be statistically significant.     

Coreceptor requirements of primary HIV type 1 group O isolates from Cameroon.

HIV-1 group O has its epicenter in Cameroon and neighboring countries and is responsible for 3 to 5% of all HIV infections in this region. It is believed that HIV-1 group O was introduced into the human population by a separate cross-species transmission, occurring independently of the HIV-1 (group M and group N) and HIV-2 transmissions. We have studied the coreceptor requirements of 12 primary HIV-1 O-type isolates from individuals with different clinical symptoms. Only 2 of these 12 viruses showed a syncytium-inducing phenotype after infection of primary peripheral blood mononuclear cells (PBMCs) and were infectious for the T cell line C8166. These isolates used CXCR4 as a coreceptor for entry, whereas the remaining isolates used only CCR5 efficiently. One isolate was able to use BOB and CCR8 as coreceptors in addition to CXCR4. All group O isolates tested were efficiently inhibited by SDF-1 or RANTES, the natural ligands of CXCR4 and CCR5, respectively. These results indicate that CXCR4 and CCR5 are the principal coreceptors for HIV-1 O-type viruses. Most of the HIV-1 group O isolates studied were derived from patients at later stages of the disease. Although HIV-1 group O and group M infections do not differ in their pathogenesis, the studied isolates did not evolve to use a broad range of coreceptors as described for HIV-1 group M and HIV-2.     

Influence of RANTES, SDF-1 and TGF-beta levels on the value of interleukin-7 as a predictor of virological response in HIV-1-infected patients receiving double boosted protease inhibitor-based therapy

OBJECTIVES: Interleukin-7 (IL-7), RANTES (regulated on activation, normal T cell expressed and secreted), stromal cell-derived factor-1 (SDF-1) and transforming growth factor-beta (TGF-beta) appear to share certain biological properties in vitro and all are involved in HIV-1 disease progression. Our earlier observations indicated that IL-7 levels decrease upon CD4 T-cell recovery and represent a new, independent predictor of virological response. Here, we examine associations among circulating levels of IL-7, RANTES, SDF-1 and TGF-beta in hopes of gaining insight into their contribution to the predictive value of IL-7. METHODS: Levels of IL-7, RANTES, SDF-1 and TGF-beta, and immune and viral parameters were assessed in HIV-1-infected patients. RESULTS: Cross-sectional (n=148) and longitudinal (n=36) analyses showed that levels of IL-7, but not RANTES, SDF-1 or TGF-beta, were increased in HIV-1-infected adults compared with those of healthy controls. In the cross-sectional study, levels of IL-7 were correlated with RANTES (r=0.31, P=0.002) and TGF-beta (r=0.53, P<0.001) but not with SDF-1 (r=0.12, P=0.22), and these associations were more pronounced in patients with CD4 T-cell counts >200 cells/microL. In contrast to IL-7, levels of RANTES, SDF-1 and TGF-beta were not correlated with CD4 T-cell counts. Longitudinal analysis revealed a marked decline in IL-7 levels accompanied by an increase in CD4 T-cell count following antiretroviral therapy (ART), but no changes in RANTES, SDF-1 or TGF-beta levels. Multivariate regression analysis showed no influence of baseline RANTES, SDF-1 or TGF-beta levels on the value of IL-7 as a predictor of virological response at 48 weeks. CONCLUSIONS: Collectively, these results indicate that changes in IL-7 levels did not induce changes in RANTES, SDF-1 or TGF-beta. Furthermore, they indicate that RANTES, SDF-1 or TGF-beta levels do not explain the predictor value of IL-7 in patients receiving ART.     

CC and CXC chemokines in breastmilk are associated with mother-to-child HIV-1 transmission

INTRODUCTION: CC and CXC chemokines may play a role in mother-to-child HIV-1 transmission by blocking HIV-1 binding to chemokine receptors and impeding viral entry into cells. METHODS: To define correlates of breastmilk chemokines and associations with infant HIV-1 acquisition, chemokines in breastmilk and infant HIV-1 infection risk were assessed in an observational, longitudinal cohort study. We measured MIP-1alpha, MIP-1beta, RANTES, and SDF-1 in month 1 breastmilk specimens from HIV-1-infected women in Nairobi and HIV-1 viral load was calculated in maternal plasma and breastmilk at delivery and 1 month postpartum. Infant infection status was determined at birth and months 1, 3, 6, 9, and 12. RESULTS: Among 281 breastfeeding women, 60 (21%) of their infants acquired HIV-1 during follow-up, 39 (65%) of whom became infected intrapartum or after birth. MIP-1alpha, MIP-1beta, RANTES, and SDF-1 were all positively correlated with breastmilk HIV-1 RNA (P<0.0005). Women with clinical mastitis had 50% higher MIP-1alpha and MIP-1beta levels (P<0.001 and P=0.006, respectively) and women with subclinical mastitis (breastmilk Na(+)/K(+)>1) had approximately 70% higher MIP-1alpha, MIP-1beta and RANTES (P<0.002 for all) compared to women without mastitis. Independent of breastmilk HIV-1, increased MIP-1beta and SDF-1 were associated with reduced risk of infant HIV-1 (RR=0.4; 95% CI 0.2-0.9; P=0.03 and RR=0.5; 95% CI=0.3-0.9; P=0.02, respectively) and increased RANTES was associated with higher transmission risk (RR=2.3; 95% CI 1.1- 5.3; P=0.04). CONCLUSIONS: These observations suggest a complex interplay between virus levels, breastmilk chemokines, and mother-to-child HIV-1 transmission and may provide insight into developing novel strategies to reduce infection across mucosal surfaces.     

Role of the HIV type 1 glycoprotein 120 V3 loop in determining coreceptor usage.

Macrophage (M)-tropic HIV-1 isolates use the beta-chemokine receptor CCR5 as a coreceptor for entry, while T cell line-adapted (TCLA) strains use CXCR4 and dual-tropic strains can use either CCR5 or CXCR4. To investigate the viral determinants involved in choice of coreceptor, we used a fusion assay based on the infection of CD4+ HeLa cells that express one or both coreceptors with Semliki Forest virus (SFV) recombinants expressing the native HIV-1 gp160 of a primary M-tropic isolate (HIV-1BX08), a TCLA isolate (HIV-1LAI), or a dual-tropic strain (HIV-1MN). We examined whether the V3 region of these glycoproteins interacts directly with the corresponding coreceptors by assaying coreceptor-dependent cell-to-cell fusion mediated by the different recombinants in the presence of various synthetic linear peptides. Synthetic peptides corresponding to different V3 loop sequences blocked syncytium formation in a coreceptor-specific manner. Synthetic V2 peptides were also inhibitory for syncytium formation, but showed no apparent coreceptor specificity. A BX08 V3 peptide with a D320 --> R substitution retained no inhibitory capacity for BX08 Env-mediated cell-to-cell fusion, but inhibited LAI Env-mediated fusion as efficiently as the homologous LAI V3 peptide. The same mutation engineered in the BX08 env gene rendered it able to form syncytia on CD4+CXCR4+CCR5-HeLa cells and susceptible to inhibition by SDF-1alpha and MIP-1beta. Other substitutions tested (D320 --> Q/D324 --> N or S306 --> R) exhibited intermediate effects on coreceptor usage. These results underscore the importance of the V3 loop in modulating coreceptor choice and show that single amino acid modifications in V3 can dramatically modify coreceptor usage. Moreover, they provide evidence that linear V3 loop peptides can compete with intact cell surface-expressed gp120/gp41 for CCR5 or CXCR4 interaction.     

Cell-dependent mechanisms restrict the HIV type 1 coreceptor activity of US28, a chemokine receptor homolog encoded by human cytomegalovirus

Several members of the chemokine receptor family are used together with CD4 for HIV-1 entry into target cells. The human cytomegalovirus US28 gene encodes a chemokine receptor homolog that has been reported to function as an HIV-1 coreceptor. However, studies of US28 have given conflicting results regarding its ability to mediate HIV-1 entry. We examined the ability of US28 to function as an HIV-1 coreceptor in various cell lines and found that its coreceptor activity is highly cell dependent. US28 could function as a coreceptor for HIV-1 entry in HeLa and U87 cells but not in COS-1 and Cf2Th cells. In COS-1 cells, US28 was expressed on the cell surface and could mediate cell-cell fusion with HIV-1 Env-expressing cells, suggesting that the block to infection may result from a defect in virus internalization or postentry steps. In Cf2Th cells, US28 was expressed at high levels intracellularly but was not transported to the cell surface. The block in US28 coreceptor function in COS-1 and Cf2Th cells was coreceptor dependent, since CCR5, CXCR4, and other coreceptors can mediate HIV-1 entry in these cell lines. HIV-1 viruses pseudotyped with the MuLV or VSV Env entered and replicated at similar efficiency in COS-1 and U87 cells in single-cycle infections, suggesting that postentry and other early events in the HIV-1 life cycle are not intrinsically inefficient in COS-1 cells. These results identify two distinct mechanisms that can restrict the HIV-1 coreceptor activity of US28 in a cell- and coreceptor-dependent manner, and help to explain the existing controversy regarding the ability of US28 to mediate HIV-1 entry.     

Elevated T cell counts and RANTES expression in the genital mucosa of HIV-1-resistant Kenyan commercial sex workers

The initial site of exposure to human immunodeficiency virus (HIV)-1 during heterosexual transmission occurs in the genital tract. Although the majority of immunological studies have focused on the immune response to HIV-1 at the systemic level, our understanding of tissue-specific immunity is deficient. The goal of the present study was to characterize T cell populations found in the cervix of women shown to be resistant to infection by HIV-1. Levels of both systemic and cervical mucosal lymphocytes were compared between HIV-1-resistant, HIV-1-uninfected, and HIV-1-infected commercial sex workers (CSWs) as well as HIV-1-uninfected non-CSW control subjects at low risk for exposure. The HIV-1-resistant CSWs had increased cervical CD4+ and CD8+ T cell counts, compared with the HIV-1-uninfected CSWs; importantly, these increases were not reflected in the systemic lymphocyte compartment. There was a 2-fold increase in CD4+ T cell counts in the HIV-1-resistant CSWs, compared with both the HIV-1-infected and the HIV-1-uninfected CSWs. Expression of the HIV-1 coreceptors CCR5 and CXCR4 was also determined, and cytokine and beta chemokine levels in the genital mucosa were assessed. The HIV-1-resistant CSWs had a 10-fold increase in RANTES expression, compared with the HIV-1-uninfected CSWs. This is the first study to show elevated levels of beta chemokines and CD4+ T cells in the genital tracts of women who are exposed to HIV-1 and yet are uninfected.