Molecular Analyses Define Vα7.2-Jα33+ MAIT Cell Depletion in HIV Infection: A Case-Control Study

Mucosal-associated invariant T (MAIT) cells are an abundant antibacterial innate-like lymphocyte population. There are conflicting reports as to their fate in HIV infection. The objective of this study was to determine whether MAIT cells are truly depleted in HIV infection.In this case-control study of HIV-positive patients and healthy controls, quantitative real-time polymerase chain reaction was used to assess the abundance of messenger RNA (mRNA) and genomic DNA (gDNA) encoding the canonical MAIT cell T cell receptor (Vα7.2-Jα33). Comparison was made with flow cytometry.Significant depletion of both Vα7.2-Jα33 mRNA and gDNA was seen in HIV infection. Depletion of Vα7.2+CD161++ T cells was confirmed by flow cytometry. In HIV infection, the abundance of Vα7.2-Jα33 mRNA correlated most strongly with the frequency of Vα7.2+CD161++ cells. No increase was observed in the frequency of Vα7.2+CD161- cells among CD3+CD4- lymphocytes.MAIT cells are depleted from blood in HIV infection as confirmed by independent assays. Significant accumulation of a CD161- MAIT cell population is unlikely. Molecular approaches represent a suitable alternative to flow cytometry-based assays for tracking of MAIT cells in HIV and other settings.

HIV testing and burden of HIV infection in black cancer patients in Johannesburg, South Africa: a cross-sectional study.

BACKGROUND HIV infection is a known risk factor for cancer but little is known about HIV testing patterns and the burden of HIV infection in cancer patients. We did a cross-sectional analysis to identify predictors of prior HIV testing and to quantify the burden of HIV in black cancer patients in Johannesburg, South Africa. METHODS The Johannesburg Cancer Case-control Study (JCCCS) recruits newly-diagnosed black cancer patients attending public referral hospitals for oncology and radiation therapy in Johannesburg . All adult cancer patients enrolled into the JCCCS from November 2004 to December 2009 and interviewed on previous HIV testing were included in the analysis. Patients were independently tested for HIV-1 using a single ELISA test . The prevalence of prior HIV testing, of HIV infection and of undiagnosed HIV infection was calculated. Multivariate logistic regression models were fitted to identify factors associated with prior HIV testing. RESULTS A total of 5436 cancer patients were tested for HIV of whom 1833[33.7% (95% CI=32.5-35.0)] were HIV-positive. Three-quarters of patients (4092 patients) had ever been tested for HIV. The total prevalence of undiagnosed HIV infection was 11.5% (10.7-12.4) with 34% (32.0-36.3) of the 1833 patients who tested HIV-positive unaware of their infection. Men >49 years [OR 0.49(0.39-0.63)] and those residing in rural areas [OR 0.61(0.39-0.97)] were less likely to have been previously tested for HIV. Men with at least a secondary education [OR 1.79(1.11-2.90)] and those interviewed in recent years [OR 4.13(2.62 - 6.52)] were likely to have prior testing. Women >49 years [OR 0.33(0.27-0.41)] were less likely to have been previously tested for HIV. In women, having children <5 years [OR 2.59(2.04-3.29)], hormonal contraceptive use [OR 1.33(1.09-1.62)], having at least a secondary education [OR:2.08(1.45-2.97)] and recent year of interview [OR 6.04(4.45-8.2)] were independently associated with previous HIV testing. CONCLUSIONS In a study of newly diagnosed black cancer patients in Johannesburg, over a third of HIV-positive patients were unaware of their HIV status. In South Africa black cancer patients should be targeted for opt-out HIV testing.

Secondary Prevention of HIV Infection: The Current State of Prevention for Positives

There remains much to be done to understand why, when, and under what conditions PLWH practice risk. substantial work also needs to be performed to design, implement, rigorously evaluate, and when effective, to disseminate widely, additional, evidencebased PfP interventions targeting diverse populations. Directing such interventions to populations of PLWH at greatest risk for transmission of HIV has the potential to yield significant impact on the pandemic.

Evidence for rapid disappearance of initially expanded HIV-specific CD8+ T cell clones during primary HIV infection

Down-regulation of the initial burst of viremia during primary HIV infection is thought to be mediated predominantly by HIV-specific cytotoxic T lymphocytes, and the appearance of this response is associated with major perturbations of the T cell receptor repertoire. Changes in the T cell receptor repertoire of virus-specific cytotoxic T lymphocytes were analyzed in patients with primary infection to understand the failure of the cellular immune response to control viral spread and replication. This analysis demonstrated that a significant number of HIV-specific T cell clones involved in the primary immune response rapidly disappeared. The disappearance was not the result of mutations in the virus epitopes recognized by these clones. Evidence is provided that phenomena such as high-dose tolerance or clonal exhaustion might be involved in the disappearance of these monoclonally expanded HIV-specific cytotoxic T cell clones. These findings should provide insights into how HIV, and possibly other viruses, elude the host immune response during primary infection.

Concomitant combination therapy for HIV infection preferable over sequential therapy with 3TC and non-nucleoside reverse transcriptase inhibitors

Exposure to 3TC of HIV-1 mutant strains containing non-nucleoside reverse transcriptase inhibitor (NNRTI)-specific mutations in their reverse transcriptase (RT) easily selected for double-mutant viruses that had acquired the characteristic 184-Ile mutation in their RT in addition to the NNRTI-specific mutations. Conversely, exposure of 3TC-resistant 184-Val mutant HIV-1 strains to nine different NNRTIs resulted in the rapid emergence of NNRTI-resistant virus strains at a time that was not more delayed than when wild-type HIV-1(IIIB) was exposed to the same compounds. The RTs of these resistant virus strains had acquired the NNRTI-characteristic mutations in addition to the preexisting 184-Val mutation. Surprisingly, when the 184-Ile mutant HIV-1 was exposed to a variety of NNRTIs, the 188-His mutation invariably occurred concomitantly with the 184-Ile mutation in the HIV-1 RT. Breakthrough of this double-mutant virus was markedly accelerated as compared with the mutant virus selected from the wild-type or 184-Val mutant HIV-1 strain. The double (184-Ile + 188-His) mutant virus showed a much more profound resistance profile against the NNRTIs than the 188-His HIV-1 mutant. In contrast with the sequential chemotherapy, concomitant combination treatment of HIV-1-infected cells with 3TC and a variety of NNRTIs resulted in a dramatic delay of virus breakthrough and resistance development.

Mice transgenic for human CD4 and CCR5 are susceptible to HIV infection

HIV entry into human cells is mediated by CD4 acting in concert with one of several members of the chemokine receptor superfamily. The resistance to HIV infection observed in individuals with defective CCR5 alleles indicated that this particular chemokine receptor plays a crucial role in the initiation of in vivo HIV infection. Expression of human CD4 transgene does not render mice susceptible to HIV infection because of structural differences between human and mouse CCR5. To ascertain whether expression of human CD4 and CCR5 is sufficient to make murine T lymphocytes susceptible to HIV infection, the lck promoter was used to direct the T cell-specific expression of human CD4 and CCR5 in transgenic mice. Peripheral blood mononuclear cells and splenocytes isolated from these mice expressed human CD4 and CCR5 and were infectible with selected M-tropic HIV isolates. After in vivo inoculation, HIV-infected cells were detected by DNA PCR in the spleen and lymph nodes of these transgenic mice, but HIV could not be cultured from these cells. This indicated that although transgenic expression of human CD4 and CCR5 permitted entry of HIV into the mouse cells, significant HIV infection was prevented by other blocks to HIV replication present in mouse cells. In addition to providing in vivo verification for the important role of CCR5 in T lymphocyte HIV infection, these transgenic mice represent a new in vivo model for understanding HIV pathogenesis by delineating species-specific cellular factors required for productive in vivo HIV infection. These mice should also prove useful for the assessment of potential therapeutic and preventative modalities, particularly vaccines.

Multiple modes of cellular activation and virus transmission in HIV infection: A role for chronically and latently infected cells in sustaining viral replication

CD4+ T cell activation, required for virus replication in these cells, occurs in local microenvironmental domains in transient bursts. Thus, although most HIV originates from short-lived virus-producing cells, it is unlikely that chronic infection is generally sustained in rapid continuous cycles of productive infection as has been proposed. Such continuity of productive infection cycles would depend on efficient long-range transmission of HIV from one set of domains to another, in turn requiring the maintenance of sufficiently high concentrations of cell-free virus across lymphoid tissues at all times. By contrast, long-lived cellular sources of HIV maintain the capacity to infect newly activated cells at close range despite the temporal and spatial discontinuities of activation events. Such proximal activation and transmission (PAT) involving chronically and latently infected cells may be responsible for sustained infection, particularly when viral loads are low. Once CD4 cells are productively infected through PAT, they can infect other activated cells in their immediate vicinity. Such events propagate locally but generally do not spread systemically, unlike in the acute phase of the infection, because of the early establishment of protective anergy. Importantly, antiretroviral drug treatment is likely to differentially impact long-range transmission and PAT.

Reconsidering targeted toxins to eliminate HIV infection: You gotta have HAART

The success of highly active anti-retroviral therapy (HAART) has inspired new concepts for eliminating HIV from infected individuals. A major obstacle is the persistence of long-lived reservoirs of latently infected cells that might become activated at some time after cessation of therapy. We propose that, in the context of treatment strategies to deliberately activate and eliminate these reservoirs, hybrid toxins targeted to kill HIV-infected cells be reconsidered in combination with HAART. Such combinations might also prove valuable in protocols aimed at preventing mother-to-child transmission and establishment of infection immediately after exposure to HIV. We suggest experimental approaches in vitro and in animal models to test various issues related to safety and efficacy of this concept.

Human immunodeficiency virus (HIV) type 2-mediated inhibition of HIV type 1: a new approach to gene therapy of HIV-infection.

Human immunodeficiency virus (HIV) type 2, the second AIDS-associated human retrovirus, differs from HIV-1 in its natural history, infectivity, and pathogenicity, as well as in details of its genomic structure and molecular behavior. We report here that HIV-2 inhibits the replication of HIV-1 at the molecular level. This inhibition was selective, dose-dependent, and nonreciprocal. The closely related simian immunodeficiency provirus also inhibited HIV-1. The selectivity of inhibition was shown by the observation that HIV-2 did not significantly downmodulate the expression of the unrelated murine leukemia virus; neither did the murine leukemia virus markedly affect HIV-1 or HIV-2 expression. Moreover, while HIV-2 potently inhibited HIV-1, the reverse did not happen, thus identifying yet another and remarkable difference between HIV-1 and HIV-2. Mutational analysis of the HIV-2 genome suggested that the inhibition follows a complex pathway, possibly involving multiple genes and redundant mechanisms. Introduction of inactivating mutations into the structural and regulatory/accessory genes did not render the HIV-2 provirus ineffective. Some of the HIV-2 gene defects, such as that of tat and rev genes, were phenotypically transcomplemented by HIV-1. The HIV-2 proviruses with deletions in the putative packaging signal and defective for virus replication were effective in inducing the suppressive phenotype. Though the exact mechanism remains to be defined, the inhibition appeared to be mainly due to an intracellular molecular event because it could not be explained solely on the basis of cell surface receptor mediated interference. The results support the notion that the inhibition likely occurred at the level of viral RNA, possibly involving competition between viral RNAs for some transcriptional factor essential for virus replication. Induction of a cytokine is another possibility. These findings might be relevant to the clinical-epidemiological data suggesting that infection with HIV-2 may offer some protection against HIV-1 infection.

Microbial translocation and immune activation in HIV infection

Trabalho Final do Curso de Mestrado Integrado em Medicina, Faculdade de Medicina, Universidade de Lisboa, 2014

HIV infection, viral hepatitis and liver fibrosis among prison inmates in West Africa.

BACKGROUND Prisoners represent a vulnerable population for blood-borne and sexually transmitted infections which can potentially lead to liver fibrosis and ultimately cirrhosis. However, little is known about the prevalence of liver fibrosis and associated risk factors among inmates in sub-Saharan Africa. METHODS Screening of liver fibrosis was undertaken in a randomly selected sample of male inmates incarcerated in Lome, Togo and in Dakar, Senegal using transient elastography. A liver stiffness measurement ≥9.5 KPa was retained to define the presence of a severe liver fibrosis. All included inmates were also screened for HIV, Hepatitis B Virus (HBV) and Hepatitis C Virus (HCV) infection. Substances abuse including alcohol, tobacco and cannabis use were assessed during face-to-face interviews. Odds Ratio (OR) estimates were computed with their 95 % Confidence Interval (CI) to identify factors associated with severe liver fibrosis. RESULTS Overall, 680 inmates were included with a median age of 30 years [interquartile range: 24-35]. The prevalence of severe fibrosis was 3.1 % (4.9 % in Lome and 1.2 % in Dakar). Infections with HIV, HBV and HCV were identified in 2.6 %, 12.5 % and 0.5 % of inmates, respectively. Factors associated with a severe liver fibrosis were HIV infection (OR = 7.6; CI 1.8-32.1), HBV infection (OR = 4.8; CI 1.8-12.8), HCV infection (OR = 52.6; CI 4.1-673.8), use of traditional medicines (OR = 3.7; CI 1.4-10.1) and being incarcerated in Lome (OR = 3.3; CI 1.1-9.8) compared to Dakar. CONCLUSIONS HIV infection and viral hepatitis infections were identified as important and independent determinants of severe liver fibrosis. While access to active antiviral therapies against HIV and viral hepatitis expands in Africa, adapted strategies for the monitoring of liver disease need to be explored, especially in vulnerable populations such as inmates.