Current HIV Research - Volume 13, Issue 6, 2015

About 35 million people worldwide were living with HIV-1 at the end of 2013 and over 25 million have already died of AIDS. AIDS patients show high variability in the speed of disease progression in the absence of treatment. While certain immunological traits have been shown to correlate with accelerated or slowed progression in some subjects, including slow progressors, factors controlling HIV-1 replication and disease kinetics remain largely enigmatic. The importance of T lymphocytes and of protective HLA-alleles is undeniable, but not sufficient to explain every attenuated phenotype. A thorough understanding of HIV-1 infection control in these patient subsets may help the development of novel strategies for treatment and prevention. Restriction factors are type I interferon-induced specialized cellular proteins that block viruses at different steps of their life cycle. TRIM5α, Mx2/MxB, TRIM22/Staf50, SAMHD1, p21/CDKN1, tetherin/BST2/CD137, APOBEC3G and APOBEC3F have all been proposed to inhibit HIV-1, often with gene variant- or cellular context-specificity. Recent evidence highlights their possible implication in AIDS disease progression. In this review, we depict their restrictive activity against HIV-1 and recapitulate the latest data on their potential role in vivo, in both normal and slow progressors.

The RV144 clinical trial in Thailand associated vaccine-induced antibodies with protective efficacy, leading to a focus in HIV vaccine research on protective antibody induction. This has necessitated greater understanding of B cell biology in humans as well as non-human primates (NHP), the principle animal model for pre-clinical HIV/SIV vaccine research. This review covers development and maturation of NHP B cells within the framework of current knowledge of human and murine B cells. Identification of many NHP B cell subpopulations is now possible, although consensus is lacking in some cases, and better distinction of some populations is still needed. Elucidation of mechanisms that control germinal center maintenance, selection of B cells into the memory cell pool, and differentiation of B cells into long-lived plasma cells remains critical for improving vaccine design. B cell dysfunction occurs during both HIV and SIV infection. Whether the processes leading to this impairment are identical in humans and NHP is not known. Uncovering the mechanisms involved could lead to improved treatment regimens. The SIV/NHP model effectively mimics HIV infection of people, but key differences between NHP and humans in antibody characteristics such as glycosylation and structure may lead to unexpected outcomes in pre-clinical studies. Important new areas for investigation include the role of B cell cytokines in the immune system and the impact of the microbiome on B cell development and maturation. Enhanced knowledge of B cells in NHP as well as humans should enable improved vaccine design, leading to induction of potent, long-lasting protective antibodies.

AIDS remains one of the world’s most serious health challenges, with 35 million people living with HIV worldwide at the end of 2013. HIV sexual transmission accounts for the overwhelming majority of people newly infected, making genital and rectal mucosal tissues the major sites of infection. This review focuses on the role of the female genital epithelial cells in the establishment of HIV infection.

The men who have sex with men (MSM) population in China has experienced a recent increase in HIV incidence. Due to the dual stigma and discrimination towards homosexuality and HIV infection, most MSM living with HIV/AIDS are hard to reach by offline intervention initiatives. We recruited HIV-positive MSM participants in Chengdu, China and assessed whether they disclosed their HIV status to partners, motivated a partner to receive testing, used condoms consistently, or initiated antiretroviral therapy. Participants were quasi-randomized to either the intervention or control arm. The intervention group was given instructions for an online program with four modules: an information exchange website, a bulletin board system, individualized online counseling with trained peer educators, and an animation game. All participants were re-assessed at 6 months. The study enrolled 202 HIV-positive MSM. The intervention group had significant increases in disclosing their HIV status to their partners (76.0% vs 61.2%, P=0.0388) and motivating partners to accept HIV testing (42.3% vs 25.5%, P=0.0156) compared with the control group, but there were no between-group differences in receiving early treatment or using condoms consistently. We found that a web-based intervention targeting HIV-positive MSM was an effective tool in increasing the uptake of HIV testing within this high-risk population.

Amino acid substitutions in HIV-1 proteins critical to the viral replication cycle have the potential to undermine successful inhibition of those targets, with some mutations leading to either reduced susceptibility to certain medications or complete drug resistance. Phenotypic tests are best suited to quantify the effects of complex mutational patterns on drug resistance; however, the relatively high cost and long turnaround time associated with phenotyping has increased the demand for in silico drug-specific models capable of accurately predicting phenotype directly from the target protein sequences. The focus of this study is on the HIV-1 integrase (IN) enzyme, which mediates integration of reversibly transcribed viral DNA into the host cell genome, and the development of predictive statistical learning models of resistance to the IN inhibitors Raltegravir (RAL) and Elvitegravir (EVG). Models were trained using datasets of IN protein sequence variants each having a known phenotype, quantified as the fold change in susceptibility to the respective inhibitor, and obtained using an experimental assay. A sequence-based approach employing n-grams relative frequencies was implemented to uniquely characterize each IN variant as a feature vector of input attributes. Models for classifying IN variants as susceptible or resistant reach cross-validation balanced accuracy rates of 89% with RAL and 85% with EVG. Additionally, regression models achieve Pearson’s correlation coefficients, between experimental and predicted log-transformed phenotypic fold change values, as high as r = 0.80 with RAL and r = 0.76 with EVG. Our results suggest that as additional training data are made publicly available, the models may hold promise as supplementary tools for making treatment decisions.

Family of retroviruses which replicates through the use of the reverse transcriptase enzyme or the enzyme needed to convert RNA to DNA for replication bears Human Immunodeficiency Virus (HIV). It causes irreversible destruction of the immune system leading to the occurrence of opportunistic infections and malignancies. The eradication of HIV is highly unlikely as the cells of the mononuclear phagocyte system (MPS) besides CD4 T lymphocytes are the specific hosts for HIV which need to be targeted even after extended blood plasma profile of antiviral drug to maintain viral suppression and reduced disease progression. Aiming the current goal, biodegradable polymeric microspheres of PLGA 50: 50 (RESOMER® 505H) were developed and evaluated. These polymeric particles encapsulating Stavudine (d4T) exhibited nearly 100% cell viability during cytotoxicity studies in comparison to pure d4T. The histological studies have revealed the in vivo biocompatibility while hemolysis studies certified the liability of formulation to be used parenteraly exhibiting no significant hemolytic toxixicty. The in vivo pharmacokinetics has shown the extended drug release from microsphere matrix upto a month. The calculated AUCtotal for d4T loaded polymeric microspheres was found to be 3341.656 μM h/ml; which was nearly 54 times than the total AUC of free d4T injected subcutaneously to the control group of animals; exhibiting the stable d4T concentration in blood avoiding fluctuation of the same indicating decreased probabilities of development of resistance against the treatment. Combination of targeted and subcutaneous administration of d4T will not only provide the stable and extended release of drug but also eradicate the hidden HIV hosted by macrophages. The concomitant regimen will potentially enhance the therapeutic efficacy with patient compliance; renewing new hopes for complete cure and improved quality of life in the AIDS patient.

Objectives: Low vitamin D status is associated with both increased disease progression and mortality in people with HIV receiving antiretroviral therapy (ART). However, data are lacking on effects of vitamin status on disease progression and CD4 cell count in people with HIV not receiving ART. We therefore evaluated effects of vitamin D deficiency (serum 25-hydroxyvitamin D [25(OH)D] <50 nmol/L) on the decline in CD4 cell count in people with HIV not receiving ART. Methods: A retrospective cohort study including people with HIV not receiving ART and with an HIV viral load of >400 copies/mL. A proportional hazards model was fitted to evaluate the effect of vitamin D status on the time to decline in CD4 cell count (<350 cells/µL), adjusted for nadir CD4 cell count, time since HIV diagnosis, previous ART use and HIVviral load. Results: 224 participants fulfilled the inclusion criteria and were followed for a median of 11 months (range or IQR). At baseline, 42% had vitamin D deficiency and the median (interquartile range) CD4 cell count was 502 (355, 662) cells/µL. HIV-infected individuals with vitamin D deficiency had an increased risk of CD4 decline to <350 cells/µL [Hazard ratio (HR) 2.15 (95% CI 1.05, 4.38, p=0.04)]. Conclusion: Vitamin D deficiency was independently associated with an increased time to decline in CD4 cell count to <350 cells/µL, but not with a change in CD4 overall in people with HIV not receiving ART.

Background: The conversion to HIV-1 single-stranded RNA into double-stranded DNA for nuclear integration is an essential viral step in replication: this process is mediated by Reverse-Transcriptase (RT) and by central polypurine tract (cPPT), a domain where the plus-strand synthesis requires viral primers produced by RNase-H cleavage. Recent studies highlighted the need of investigating the role of RNase-H in RT nucleoside-inhibitors-resistance, because specific mutation(s) could affect cPPT removal and RNase-H cleavage specificity. Thus, the variability of RNase-H and cPPT were studied. Methods: HIV-1 subtype-B sequences from 746 drug-naïve and 806 antiretroviral-(ARV)-treated patients were used and analysed. Results: In drug-naïve patients, among 54 RNase-H variable residues, 25 were mutated in >5% of patients, and 7 of them were highly variable (>25%), whilst in ARV-treated individuals, 53 RNase-H variable residues were observed, which 24 were mutated in >5% of patients and 6 of them were highly variable (>25%). Differently, a high conservation was observed in cPPT-area, with no statistically significant differences observed between the two datasets analysed. Nevertheless, in ARV-treated patients the variability of cPPT nucleotide at position 6 was found three times higher with respect to the drug-naïve dataset. The topology of the dendrogram has revealed the existence of a cluster (boostrap=0.98) grouping the A6GcPPT with V531I and S519N RNase-H signatures. Conclusion: These signatures observed within cPPT and mostly in RNase-H, warrant advanced structural analysis to delineate their potential roles in the affinity/recognition of RT and the cleavage capacity of RNase-H. Exploring further the implications such changes may have on drug-resistance may be relevant.