Monocytes and macrophages play a prominent role in the establishment of HIV-1 infection, virus dissemination and development of viral reservoirs. Like T cells, macrophages display immune polarization that can promote or impair adaptive immunity. We hypothesize that dysregulation of monocyte/macrophage activation and differentiation may promote immune dysfunction and contribute to AIDS pathogenesis. Using flow cytometry, we analyzed the frequency of monocyte subsets in human immunodeficiency virus type 1 (HIV-1) infection relative to seronegative controls, focusing on the CD163+/CD16+ monocyte as a likely precursor of the “alternatively-activated” macrophage. Individuals with detectable HIV-1 infection showed an increase in the frequency of CD163+/CD16+ monocytes (CD14+) when compared to seronegative or HIV-1 infected persons with undetectable viral loads. A positive correlation between increased CD163+/CD16+ monocyte frequency and viral load was revealed that was not seen between viral load and the number of CD4+ T cells or frequency of CD16+ monocytes (without CD163 sub-typing). We also found strong inverse correlations between CD16+ monocytes (r=-0.71, r2=0.5041, p=0.0097) or CD163+/CD16+ monocytes (r=-0.86, r2=0.7396, p=0.0003) and number of CD4+ T cells below 450 cells/μl. An inverse relationship between CD163+/CD16+ and CD163+/CD16− monocytes suggests the expanded CD163+/CD16+ population is derived exclusively from within the “alternatively activated” (MΦ-2) subset. These data suggest a potential role for CD163+/CD16+ monocytes in virus production and disease progression. CD163+/CD16+ monocytes may be a useful biomarker for HIV-1 infection and AIDS progression and a possible target for therapeutic intervention.
As HAART becomes more accessible in sub-Saharan Africa, metabolic syndromes, body fat redistribution (BFR), and cardiovascular disease may become more prevalent. We conducted a 6-month, randomized controlled trial to test whether cardiorespiratory exercise training (CET), improves metabolic, body composition and cardiorespiratory fitness parameters in HAART-treated HIV+ African subjects with BFR. Six months of CET reduced waist circumference (−7.13 ± 4.4 cm, p < 0.0001), WHR (−0.10 ± 0.1, p < 0.0001), sum skinfold thickness (−6.15 ± 8.2 mm, p < 0.0001) and % body fat mass (−1.5 ± 3.3, p < 0.0001) in HIV+BFR+EXS. Hip circumference was unchanged in non-exercise control groups. CET reduced fasting total cholesterol (−0.03 ± 1.11 mM, p < 0.05), triglycerides (−0.22 ± 0.48 mM, p < 0.05) and glucose levels (−0.21 ± 0.71 mM, p < 0.05) (p < 0.0001). HDL-, LDL-cholesterol and HOMA values were unchanged after CET. Interestingly, HIV+ subjects randomized to non-exercising groups experienced increases in fasting plasma glucose levels, whereas HIV seronegative controls did not (p < 0.001). Predicted VO2 peak increased more in the HIV+BFR+EXS than in all other groups (4.7 ± 3.9 ml/kg/min, p < 0.0001). Exercise training positively modulated body composition and metabolic profiles, and improved cardiorespiratory fitness in HAART-treated HIV+ Africans. These beneficial adaptations imply that exercise training is a safe, inexpensive, practical, and effective treatment for evolving metabolic and cardiovascular syndromes associated with HIV and HAART exposure in resource-limited sub-Saharan countries, where treatment is improving, morbidity and mortality rates are declining, but where minimal resources are available to manage HIV- and HAART-associated cardiovascular and metabolic syndromes.
Factors explaining why human immunodeficiency virus (HIV) enhances the risk of reactivated tuberculosis (TB) are poorly understood. Unfortunately, experimental models of HIV-induced reactivated TB are lacking. We examined whether cynomolgus macaques, which accurately model latent TB in humans, could be used to model pathogenesis of HIV infection in the lungs and associated lymph nodes. These experiments precede studies modeling the effects of HIV infection on latent TB. We infected two groups of macaques with chimeric simian–human immunodeficiency viruses (SHIV-89.6P and SHIV-KU2) and followed viral titers and immunologic parameters including lymphocytes numbers and phenotype in the blood, bronchoalveolar lavage cells, and lymph nodes over the course of infection. Tissues from the lungs, liver, kidney, spleen, and lymph nodes were similarly examined at necropsy. Both strains produced dramatic CD4+ T cell depletion. Plasma titers were not different between viruses, but we found more SHIV-89.6P in the lungs. Both viruses induced similar patterns of cell activation markers. SHIV-89.6P induced more IFN-γ expression than SHIV-KU2. These results indicate SHIV-89.6P and SHIV-KU2 infect cynomolgus macaques and may be used to accurately model effects of HIV infection on latent TB.
This study compared the role of genotypic susceptibility scores (GSS) as a predictor of virologic response in a group (n = 234) of HIV-infected, protease inhibitor (PI)-experienced subjects. Two scoring methods [discrete genotypic susceptibility score (dGSS) and continuous genotypic susceptibility score (cGSS)] were developed. Each drug in the subject's regimen was given a binary susceptibility score using Stanford inferred drug resistance scores to calculate the dGSS. In contrast to the dGSS, the cGSS model was designed to reflect partial susceptibility to a drug. Both GSS were independent predictors of week 16 virologic response. We also compared the GSS to a phenotypic susceptibility score (PSS) model on a subset of subjects that had both GSS and PSS performed, and found that both models were predictive of virologic response. Genotypic analyses at enrollment showed that subjects who were virologic nonresponders at week 16 revealed enrichment of several mutated codons associated with nucleoside reverse transcriptase inhibitors (NRTI) (codons 67, 69, 70, 118, 215, and 219) or PI resistance (codons 10, 24, 71, 73, and 88) compared to subjects who were virologic responders. Regression analyses revealed that protease mutations at codons 24 and 90 were most predictive of poor virologic response, whereas mutations at 82 were associated with enhanced virologic response. Certain NNRTI-associated mutations, such as K103N, were rapidly selected in the absence of NRTIs. These data indicate that GSS may be a useful tool in selecting drug regimens in HIV-1-infected subjects to maximize virologic response and improve treatment outcomes.
Most current assays of HIV antiviral resistance are based on either sequencing of viral genes (genotypic assays) or amplification and insertion of these genes into standardized virus backbones and culture. These latter are called phenotypic assays. But the only generally accepted phenotypic assay is based upon culture of intact patient virus, performed in phytohemagglutinin-activated peripheral blood mononuclear cells (PHA blasts) in the presence of differing drug concentrations. However, PHA blast culture is difficult and not always reproducible. Therefore we have sought cell lines that may produce more predictable results, yet faithfully mirror results in PHA blasts. We have compared 10 different cell lines for receptor and coreceptor expression, growth of laboratory-adapted strains of HIV, growth by direct inoculation of PBMC from infected patients, and in assays of antiviral drug effects. One of these cell lines, C8166-R5, is statistically not inferior to CD8-depleted PHA blasts for culturing HIV from the peripheral blood cells of patients. The effective concentrations of antiviral drugs of all classes were similar when assayed in C8166-R5 or PHA blasts. Known drug-resistant isolates grown in C8166-R5 demonstrated the predicted effects. We followed a patient longitudinally and demonstrated that resistance testing in C8166-R5 was predictive of clinical outcome. These experiments represent the first steps in developing a clinically useful phenotypic drug resistance assay based upon culturing the patient’s own virus.
Ribonucleases are evoking medical interest because of their intrinsic cytotoxic activity. Most notably, ranpirnase, which is an amphibian ribonuclease, is in advanced clinical trials as a chemotherapeutic agent for the treatment of cancer. Here, we describe a strategy to create a novel antiviral agent based on bovine pancreatic ribonuclease (RNase A), a mammalian homologue of ranpirnase. Specifically, we have linked the N- and C-termini of RNase A with an amino-acid sequence that is recognized and cleaved by human immunodeficiency virus (HIV) protease. This linkage obstructs the active site, forming an HIV-specific RNase A zymogen. Cleavage by HIV-1 protease increases ribonucleolytic activity by 50-fold. By relying on the proper function of HIV-1 protease, rather than its inhibition, our approach will not engender known mechanisms of resistance. Thus, we report an initial step towards a new class of agents for the treatment of HIV/AIDS.
Human immunodeficiency virus (HIV-1) variants in brain primarily use CCR5 for entry into macrophages and microglia, but dual-tropic (R5X4) HIV-1 has been detected in brain and cerebral spinal fluid (CSF) of some patients with HIV-associated dementia (HAD). Here, we sequenced the gp120 coding region of nine full-length dual-tropic (R5X4) env genes cloned directly from autopsy brain and spleen tissue from an AIDS patient with severe HAD. We then compiled a dataset of 30 unique clade B R5X4 Env V3 sequences from this subject and 16 additional patients (n = 4 brain and 26 lymphoid/blood) and used it to compare the ability of six bioinformatic algorithms to correctly predict CXCR4 usage in R5X4 Envs. Only one program (SVMgeno2pheno) correctly predicted the ability of R5X4 Envs in this dataset to use CXCR4 with 90% accuracy (n = 27/30 predicted to use CXCR4). The PSSMSINSI, Random Forest, and SVMgenomiac programs and the commonly used charge rule correctly predicted CXCR4 usage with >50% accuracy (22/30, 16/30, 19/30, and 25/30, respectively), while the PSSMX4R5 matrix and “11/25” rule correctly predicted CXCR4 usage in <50% of the R5X4 Envs (10/30 and 13/30, respectively). Two positions in the V3 loop (19 and 32) influenced coreceptor usage predictions of nine R5X4 Envs from patient MACS1 and a total of 12 Envs from the dataset (40% of unique V3 sequences). These results demonstrate that most predictive algorithms underestimate the frequency of R5X4 HIV-1 in brain and other tissues. SVMgeno2pheno is the most accurate predictor of CXCR4 usage by R5X4 HIV-1.
Infections and inflammation in the genital tract can influence HIV expression or HIV susceptibility. The goal of this study was to determine if significant relationships exist between cytokines and HIV in genital tract secretions from 57 HIV-seropositive Rwandan women. Genital tract secretions were obtained by cervicovaginal lavage (CVL). Ten different cytokines in CVL were measured by multiplex Cytometric Bead Arrays. HIV RNA in CVL and plasma were measured by quantitative PCR. In univariate analysis, genital tract HIV RNA was significantly associated with plasma HIV RNA and several of the cytokines, while in multivariate analysis, genital tract HIV RNA was only significantly associated with plasma HIV RNA and IL-6. This association of IL-6 with HIV RNA levels suggests that IL-6 is an indicator for conditions that induce HIV expression and that IL-6 may contribute to induction of HIV expression in the genital tract.
Although many interactions between HIV-1 and human proteins have been reported in the scientific literature, no publicly accessible source for efficiently reviewing this information was available. Therefore, a project was initiated in an attempt to catalogue all published interactions between HIV-1 and human proteins. HIV-related articles in PubMed were used to develop a database containing names, Entrez GeneIDs, and RefSeq protein accession numbers of interacting proteins. Furthermore, brief descriptions of the interactions, PubMed identification numbers of articles describing the interactions, and keywords for searching the interactions were incorporated. Over 100,000 articles were reviewed, resulting in the identification of 1448 human proteins that interact with HIV-1 comprising 2589 unique HIV-1-to-human protein interactions. Preliminary analysis of the extracted data indicates 32% were direct physical interactions (e.g., binding) and 68% were indirect interactions (e.g., up-regulation through activation of signaling pathways). Interestingly, 37% of human proteins in the database were found to interact with more than one HIV-1 protein. For example, the signaling protein mitogen-activated protein kinase 1 has a surprising range of interactions with 10 different HIV-1 proteins. Moreover, large numbers of interactions were published for the HIV-1 regulatory protein Tat and envelope proteins: 30% and 33% of total interactions identified, respectively. The database is accessible at http://www.ncbi.nlm.nih.gov/RefSeq/HIVInteractions/ and is cross-linked to other National Center for Biotechnology Information databases and programs via Entrez Gene. This database represents a unique and continuously updated scientific resource for understanding HIV-1 replication and pathogenesis to assist in accelerating the development of effective therapeutic and vaccine interventions.
To design a vaccine that will remain potent against HIV-1, the immunogenic regions in the viral envelope that tend to change as well as those that remain constant over time must be identified. To determine the neutralization profiles of sequential viruses over time and study whether neutralization patterns correlate with sequence evolution, 12 broadly neutralizing plasmas from HIV-1 subtype B-infected individuals were tested for their ability to neutralize sequential primary HIV-1 subtype B viruses from four individuals. Three patterns of neutralization were observed, including a loss of neutralization sensitivity by viruses over time, an increase in neutralization sensitivity by sequential viruses, or a similarity in the sensitivity of sequential viruses to neutralization. Seven to 11 gp160 clones from each sequential virus sample were sequenced and analyzed to identify mutational patterns. Analysis of the envelope sequences of the sequential viruses revealed changes characteristic of the neutralization patterns. Viruses that evolved to become resistant to neutralizing antibodies also evolved with diverse sequences, with most of the changes being due to nonsynonymous mutations occurring in the V1/V2, as well as in the constant regions (C2, C3, C4), the most changes occurring in the C3. Viruses from the patient that evolved to become more sensitive to neutralization exhibited less sequence diversity with fewer nonsynonymous changes that occurred mainly in the V1/V2 region. The V3 region remained constant over time for all the viruses tested. This study demonstrates that as viruses evolve in their host, they either become sensitive or resistant to neutralization by antibodies in heterologous plasma and mutations in different envelope regions account for these changes in their neutralization profiles.
Our aim was to elucidate the mechanism by which HIV transmission is increased following obstetrical hemorrhage. We investigated whether fetal allostimulation of maternal cells, which could occur following fetal-to-maternal hemorrhage, increases proliferation, HIV replication, and cellular activation. Peripheral blood mononuclear cells (PBMCs) were collected from HIV-infected mothers and their infants to assess maternal-fetal allostimulation. Responses were compared to allostimulation with unrelated donors. Maternal and fetal cells were cocultured to assess allogeneic stimulation. Cell proliferation was measured by [3H]thymidine incorporation and cell activation was assessed via fluorochrome-labeled antibody staining and flow cytometric analysis. Virus production from HIV-infected maternal cells was quantitated by p24 enzyme-linked immunosorbent assay or by branched chain DNA assay. Allostimulation with fetal cells led to maternal cell proliferation. In women with unsuppressed viral loads, virus release was also enhanced following allostimulation of maternal cells with fetal cells. Fetal cells are capable of allogeneically stimulating maternal cells, with responses comparable to those seen following allostimulation with unrelated donors. Allostimulation of maternal cells by fetal cells results in statistically significant increases in proliferation and enhanced HIV replication, suggesting a possible physiological mechanism for mother-to-child transmission of HIV in women with obstetrical hemorrhage.
Rare individuals report repeated unprotected HIV-1 sexual exposures, yet remain seronegative for years. We investigated the possibility that reduced in vitro CD4+ T cell susceptibility to HIV-1 infection protects such highly exposed seronegative (ES) individuals. Susceptibility to three R5-tropic HIV-1 isolates, regardless of inoculating dose, was remarkably similar between 81 ES and 33 low-risk controls. In 94% (99/105) of donors, we observed a 1.36 log-unit range in HIV-1JR-CSF production, with similar results for HIV-11192. The median frequency of intracellular Gag+ T cells after single-round infection was similar in ES (5.2%) and controls (7.2%), p = 0.456. However, in repeated testing, CD4+ T cells from two controls (6.1%) and four ES (4.9%) exhibited a 10- to 2500-fold reduction in HIV-1 production and required 5- to 12-fold greater HIV-11192 and HIV-1JR-CSF inocula to establish infection (TCID50). Reduced viral entry cannot explain the low producer phenotype; no differences in CCR5 receptor density or β-chemokine production were observed. In conclusion, we have identified a remarkably narrow range of HIV-1 susceptibility in seronegative donors regardless of risk activity, which can be applied as a benchmark to assess vaccine-induced antiviral effector activities. However, CD4+ T cells from a subset of individuals demonstrated reduced HIV-1 susceptibility unexplained by impaired entry, lending support to the possibility that cellular restriction of HIV-1 may account for continued seronegativity in some of those having repeated sexual exposure. Identifying the host–virus interactions responsible for diminished in vitro susceptibility may contribute to the development of novel therapeutic strategies.
Rare individuals report repeated unprotected HIV-1 sexual exposures, yet remain seronegative for years. We investigated the possibility that reduced in vitro CD4+ T cell susceptibility to HIV-1 infection protects such highly exposed seronegative (ES) individuals. Susceptibility to three R5-tropic HIV-1 isolates, regardless of inoculating dose, was remarkably similar between 81 ES and 33 low-risk controls. In 94% (99/105) of donors, we observed a 1.36 log-unit range in HIV-1JR-CSF production, with similar results for HIV-11192. The median frequency of intracellular Gag+ T cells after single-round infection was similar in ES (5.2%) and controls (7.2%), p = 0.456. However, in repeated testing, CD4+ T cells from two controls (6.1%) and four ES (4.9%) exhibited a 10- to 2500-fold reduction in HIV-1 production and required 5- to 12-fold greater HIV-11192 and HIV-1JR-CSF inocula to establish infection (TCID50). Reduced viral entry cannot explain the low producer phenotype; no differences in CCR5 receptor density or β-chemokine production were observed. In conclusion, we have identified a remarkably narrow range of HIV-1 susceptibility in seronegative donors regardless of risk activity, which can be applied as a benchmark to assess vaccine-induced antiviral effector activities. However, CD4+ T cells from a subset of individuals demonstrated reduced HIV-1 susceptibility unexplained by impaired entry, lending support to the possibility that cellular restriction of HIV-1 may account for continued seronegativity in some of those having repeated sexual exposure. Identifying the host-virus interactions responsible for diminished in vitro susceptibility may contribute to the development of novel therapeutic strategies.
Ribonucleases are evoking medical interest because of their intrinsic cytotoxic activity. Most notably, ranpirnase, which is an amphibian ribonuclease, is in advanced clinical trials as a chemotherapeutic agent for the treatment of cancer. Here, we describe a strategy to create a novel antiviral agent based on bovine pancreatic ribonuclease (RNase A), a mammalian homologue of ranpirnase. Specifically, we have linked the N- and C-termini of RNase A with an amino acid sequence that is recognized and cleaved by human immunodeficiency virus (HIV) protease. This linkage obstructs the active site, forming an HIV-specific RNase A zymogen. Cleavage by HIV-1 protease increases ribonucleolytic activity by 50-fold. By relying on the proper function of HIV-1 protease, rather than its inhibition, our approach will not engender known mechanisms of resistance. Thus, we report an initial step toward a new class of agents for the treatment of HIV/AIDS.
Strategies for purging persistent reservoirs in human immunodeficiency virus (HIV)-infected individuals may be enhanced by including agents that specifically kill virus-expressing cells. Anti-HIV envelope immunotoxins (ITs) represent one class of candidate molecules that could fulfill this function. We have previously utilized an anti-gp120 IT in conjunction with various stimulants to kill latently infected T cells ex vivo. Here we show that primary macrophages expressing HIV Env are relatively refractory to killing by IT when used alone. However, including stimulants such as prostratin or granulocyte–macrophage colony-stimulating factor to increase HIV gene expression in infected macrophages enhanced IT-mediated killing. Therefore, “activation–elimination” strategies similar to those proposed for purging the latent HIV reservoir may prove useful in clearing chronically infected macrophages in vivo.
The durability of HAART regimens is often limited by antiretroviral toxicity and nonadherence, which lead to virologic failure. We sought to determine sociodemographic and psychosocial patient factors predictive of short-term discontinuation of HAART regimens overall and stratified by the reason for discontinuation. A retrospective cohort study of the UAB 1917 Clinic Cohort evaluated short-term HAART regimen discontinuation (within 12 months of regimen initiation) between 1/1995 and 8/2004 classified as (1) gastrointestinal (GI) toxicity, (2) non-GI toxicity, (3) virologic failure or nonadherence (VF/NA), (4) loss to follow-up, and (5) other. Multivariable multinomial logistic regression models accounting for dependent observations were fit to assess the relationship between patient factors and type-specific regimen discontinuation. Among the 738 study participants, 1026 of 1852 HAART regimens (55%) were discontinued within 12 months of initiation. In multivariable analysis, discontinuation for GI toxicity was more common in patients lacking private health insurance and those with a history of intravenous (IV) drug use, whereas non-GI toxicity was more common in younger patients and females. African-American patients and those with a history of IV drug use were more likely to stop a regimen due to VF/NA. Loss to follow-up was more common in younger patients, individuals who were uninsured, and those with a history of IV drug use. Short-term discontinuation of HAART regimens is more common in vulnerable populations that bear a disproportionate burden of the U.S. HIV/AIDS epidemic. More vigilant monitoring of patient populations at higher risk of toxicity and virologic failure may allow for improved HAART regimen durability.
We investigated the association between plasma HIV-1 RNA, immune activation, and polyclonal T cell function in viremic subjects whether on or off antiretroviral therapy (ART). The surface expression of activation/functional molecules on T cells and monocytes as well as cytokine secretion and T cell proliferation were assessed in 23 HIV-1− and 79 HIV-1+-infected subjects with different levels of viral suppression and CD4+ T cell count >250 cells/mm3 for >6 months. Viral replication was associated with increased T cell and monocyte activation irrespective of ART. In subjects with a detectable viral load on ART, we found a positive association with anti-CD3/CD28-induced T cell proliferation compared to patients with undetectable viral load (<400 copies/ml). No difference among groups was observed for anti-CD3/CD28-mediated IFN-γ responses. The presence of an unexpected positive association between polyclonal T cell proliferation and viral load in subjects with levels of T cell IFN-γ responses comparable to those of uninfected subjects is of potential relevance to an increase in T cell activation response before the loss of polyclonal cytokine secretion and proliferation observed with disease progression. This finding suggests that T cell hyperresponsiveness may play a role in the pathogenesis of immune comorbidities on ART.
Depletion of mitochondrial DNA (mtDNA) and mtDNA-encoded respiratory chain proteins in subcutaneous (SC) fat from patients with HIV lipoatrophy have clearly demonstrated the role of mitochondrial dysfunction in this syndrome. Research in HIV lipoatrophy, however, has been severely hampered by the lack of a suitable surrogate marker in blood or other easily obtained clinical specimens as fat biopsies are invasive and mtDNA levels in peripheral blood mononuclear cells (PBMC) do not consistently correlate with the disease process. We used a simple, rapid, quantitative 2-site dipstick immunoassay to measure OXPHOS enzymes Complex I (CI) and Complex IV (CIV), and rtPCR to measure mtDNA in 26 matched SC fat and PBMC specimens previously banked from individuals on potent antiretroviral (ARV) therapy with HIV lipoatrophy, on similar ARV therapy without lipoatrophy, and in HIV seronegative controls. Significant correlations were found between the respective PBMC and fat levels for both CI (r = 0.442, p = 0.024) and for CIV (r = 0.507, p = 0.008). Both CI and CIV protein levels were also significantly reduced in both PBMCs and fat in lipoatrophic subjects compared to HIV seronegative controls (p ≤ 0.05), while a comparative reduction in mtDNA levels in lipoatrophic subjects was observed only in fat. We conclude that CI and CIV levels in PBMCs correlate to their respective levels in fat and may have utility as surrogate markers of mitochondrial dysfunction in lipoatrophy.
The role specific reverse transcriptase (RT) drug resistance mutations play in influencing phenotypic susceptibility to RT inhibitors in virus strains with complex resistance interaction patterns was assessed using recombinant viruses that consisted of RT-PCR-amplified pol fragments derived from plasma HIV-1 RNA from two treatment-experienced patients. Specific modifications of key RT amino acids were performed by site-directed mutagenesis. A panel of viruses with defined genotypic resistance mutations was assessed for phenotypic drug resistance. Introduction of M184V into several different clones expressing various RT resistance mutations uniformly decreased susceptibility to abacavir, lamivudine, and didanosine, and increased susceptibility to zidovudine, stavudine, and tenofovir; replication capacity was decreased. The L74V mutation had similar but slightly different effects, contributing to decreased susceptibility to abacavir, lamivudine, and didanosine and increased susceptibility to zidovudine and tenofovir, but in contrast to M184V, L74V contributed to decreased susceptibility to stavudine. In virus strains with the nonnucleoside reverse transcriptase inhibitor (NNRTI) mutations K101E and G190S, the L74V mutation increased replication capacity, consistent with published observations, but replication capacity was decreased in strains without NNRTI resistance mutations. K101E and G190S together tend to decrease susceptibility to all nucleoside RT inhibitors, but the K103N mutation had little effect on nucleoside RT inhibitor susceptibility. Mutational interactions can have a substantial impact on drug resistance phenotype and replication capacity, and this has been exploited in clinical practice with the development of fixed-dose combination pills. However, we are the first to report these mutational interactions using molecularly cloned recombinant strains derived from viruses that occur naturally in HIV-infected individuals.
To study HIV-1 genetic diversity among HIV-positive men who have sex with men (MSM) in China, a cohort consisting of HIV-positive MSM was established in 2005 and was monitored every 2 years. In 2007, 44 HIV-positive MSM subjects were genotyped, and the results showed HIV-1 subtype B decreased from 77.5% to 41.9%, but non-B subtypes increased rapidly represented by CRF01_AE from 3.7% to 30.2% compared to 2005. In addition, one case of CRF07_BC was first identified in this population, which mainly circulated among HIV-1-infected injection drug users (IDUs) in China. There were 11 unique recombinant forms (URFs) consisting of a recombination of CRF01_AE with subtype B or CRF07_BC. The subtype-specific phylogenic tree analysis showed that the genetic distance within subtype B group viruses was larger than the genetic distance within the CRF01_AE group (p < 0.001). Of the identified viruses in the Chinese MSM population, over 80% of subtype B viruses might originate from the United States and Brazil, and over 85% of the CRF01_AE viruses might originate from Thailand. In addition, epidemic study data showed that some of the HIV-1-infected MSM had foreign sexual partners (13.6%) and heterosexual activities (43.2%). The patients infected with HIV-1 URF viruses had more heterosexual encounters (54.5%) and more sexual partners (72.7%) compared to those infected with subtype B (44.4%; 33.3%) and CRF01_AE (23.1%; 69.2%) viruses. Taken together, we suspected that the genetic complexity of HIV-1 viruses identified in Chinese MSM populations was more likely a result of multiple introductions of viruses from the general population infected with HIV-1 through IDUs or heterosexual transmission.
HIV dynamics in seminal plasma during primary HIV infection was evaluated through an observational study of individuals with primary HIV infection at the University of Washington Primary Infection Clinic. Seminal plasma HIV RNA was quantified using a real-time reverse transcription PCR assay. Blood plasma RNA was quantified by bDNA or PCR-based assays. Longitudinal analyses of HIV RNA levels over time used random effects regression analysis. From 1993 to 2005, 110 men collected 327 semen specimens. Initial blood and seminal plasma RNA levels in untreated men were only moderately correlated (Spearman r = 0.38, p = 0.0002). Estimated peak and set point levels were lower in semen than blood by 0.8 (p = 0.001) and 0.7 (p < 0.001) log10 copies/ml, respectively. RNA decay rates were similar in the two compartments (p = 0.4). For 2 months after infection, mean HIV RNA levels in seminal plasma remained above a threshold level (3.8 log10 copies/ml) that has been associated with recovery of infectious virus in vitro. HIV-positive men are likely to be most infectious in the first months following HIV acquisition. However, the modest relationship between HIV RNA levels in blood and seminal plasma suggests that the relative risk of HIV transmission during primary infection may vary from current estimates that are solely based on blood levels. Incorporating seminal plasma HIV levels into future mathematical models may increase the accuracy of these models.
The APOBEC family of mammalian cytidine deaminases, such as APOBEC3G (hA3G), has been demonstrated to function as a host viral restriction factor against HIV-1. hA3G has been shown to cause extensive G-to-A mutations in the HIV-1 genome, which may play a role in viral restriction. To investigate the role of G-to-A mutations in HIV-1 pathogenesis, we isolated, amplified, and sequenced HIV-1 sequences (vif, gag, and env) from 29 therapy-naive HIV-1-infected individuals. The levels of G-to-A mutations correlated with the expression levels of hA3G in the vif (rho = 0.438, p = 0.041) and the env regions (rho = 0.392, p = 0.038), but not in the gag region (rho = 0.131, p = 0.582). There is no correlation between viral load and the level of G-to-A mutations in the vif (rho = 0.144, p = 0.522), env (rho = 0.168, p = 0.391), or gag regions (rho = −0.254, p = 0.279). Taken together, these findings suggest that the hA3G-induced G-to-A mutations may not be the mechanism by which hA3G restricts or controls viral replication. Thus, hA3G might be restricting viral growth in infected individuals through a mechanism that is independent of the cytidine deaminase activities of hA3G.
We evaluated the association between two antiretroviral therapy (ART) adherence measurements—the medication possession ratio (MPR) and patient self-report—and detectable HIV viremia in the setting of rapid service scale-up in Lusaka, Zambia. Drug adherence and outcomes were assessed in a subset of patients suspected of treatment failure based on discordant clinical and immunologic responses to ART. A total of 913 patients were included in this analysis, with a median time of 744 days (Q1, Q3: 511, 919 days) from ART initiation to viral load (VL) measurement. On aggregate over the period of follow-up, 531 (58%) had optimal adherence (MPR ≥95%), 306 (34%) had suboptimal adherence (MPR 80–94%), and 76 (8%) had poor adherence (MPR <80%). Of the 913 patients, 238 (26%) had VL ≥400 copies/ml when tested. When compared to individuals with optimal adherence, there was increasing risk for virologic failure in those with suboptimal adherence [adjusted relative risk (ARR): 1.3; 95% confidence interval (CI): 1.0, 1.6] and those with poor adherence (ARR: 1.7; 95% CI: 1.3, 2.4) based on MPR. During the antiretroviral treatment course, 676 patients (74%) reported no missed doses. The proportion of patients with virologic failure did not differ significantly among those reporting any missed dose from those reporting perfect adherence (26% vs. 26%, p = 0.97). Among patients with suspected treatment failure, a lower MPR was associated with higher rates of detectable viremia. However, the suboptimal sensitivity and specificity of MPR limit its utility as a sole predictor of virologic failure.
HIV-1 superinfection may occur at a rate similar to that of initial infection, raising concerns for HIV-1 vaccine strategies predicated on eliciting immune responses similar to those in natural infection. Because of the high rate of recombination during HIV-1 replication, studies examining only one region of the HIV-1 genome are likely to miss cases of HIV-1 superinfection. We examined HIV-1 gag sequences from 14 high-risk Kenyan women in whom superinfection was not detected in a previous study of env sequences. We detected two additional cases of HIV-1 superinfection: one intersubtype superinfection that occurred between 1046 and 1487 days postinfection (DPI) and one intrasubtype superinfection that occurred between 341 and 440 DPI. Our results suggest that studies that examine only small genome regions may lead to underestimates of the risk of superinfection, highlighting the need for more extensive studies examining multiple regions of the HIV-1 genome.
We analyzed genetic linkage of nevirapine (NVP) resistance mutations and the genetic complexity of HIV-1 variants in Ugandan infants who were HIV-infected despite single dose (SD) prophylaxis. Plasma samples were obtained from six HIV-infected infants who had two or more NVP resistance mutations detected by population sequencing (ViroSeq). ViroSeq PCR products were cloned and transformed, and a single step amplification-sequencing reaction (AmpliSeq) was used to analyze NVP resistance mutations in cloned HIV-1 variants directly from bacterial colonies. Fifty clones were analyzed for each infant sample. This analysis revealed numerous NVP resistance mutations not detected by population sequencing, genetically-linked NVP resistance mutations, and a high degree of genetic complexity at codons that influence NVP susceptibility.