HIV-1 replication cycle

The HIV-1 is a formidable pathogen with establishment of a persistent infection based on the ability to integrate the proviral genome into chronically infected cells, and by the rapid evolution made possible by a high mutation rate and frequent recombination during the viral replication. HIV-1 has a variety of novel genes that facilitate viral persistence and regulation of HIV replication, but this virus also usurps cellular machinery for HIV replication, particularly during gene expression and virion assembly and budding. Recent success with antiretroviral therapy may be limited by the emergence HIV drug resistance and by toxicities and other requirements for successful long-term therapy. Further investigation of HIV-1 replication may allow identification of novel targets of antiretroviral therapy that may allow continued virus suppression in patients of failing current regiments, particularly drugs that target HIV-1 entry and HIV-1 integration.     

Mechanism of HIV antiretroviral drugs progress toward drug resistance

The rapid replication rate of HIV-1 RNA and its inherent genetic variation have led to the production of many HIV-1 variants with decreased drug susceptibility. The capacity of HIV to develop drug resistance mutations is a major obstacle to long-term effective anti-HIV therapy. Incomplete suppression of viral replication with an initial drug regimen diminishes the clinical benefit to the patient and may promote the development of broader drug resistance that may cause subsequent treatment regimens to be ineffective. The increased clinical use of combination antiretroviral treatment for HIV-1 infection has led to the selection of viral strains resistant to multiple drugs, including strains resistant to all licensed nucleoside analog RT inhibitors and protease inhibitors. Therefore, it is important to understand the influence of such mutations on viral properties such as replicative fitness, fidelity, and mutation rates. Although research continues to improve our understanding of resistance, leading to refined treatment strategies and, in some cases, improved outcome, resistance to antiretroviral therapy remains a major cause of treatment failure among patients living with HIV-1.     

Immunosuppressive drugs as an adjuvant to HIV treatment

Although highly active antiretroviral therapy (HAART) has dramatically changed the epidemiological impact of HIV infection, many problems with currently used antiretroviral therapy have underscored the urgent need for additional therapeutic approaches. Structured treatment interruption trials, which can be considered an immune-based therapy with an autologous virus, have failed to control viral replication in most chronically HIV-1-infected patients. Alternative approaches could be the use of immunosuppressive drugs to enhance the control of viral replication mediated by their immune and antiviral properties. The use of immunosuppressive drugs may reduce the number of activated CD4 cells that support massive virus production and may prevent sequestration of CD4 T cells into lymphoid tissue, which is the place of antigen presentation and productive HIV infection. The strategy of using drugs that interfere with the HIV life-cycle, acting on the target cells of HIV rather than on viral enzymes, offers the advantage of avoiding the development of antiretroviral drug-resistant HIV mutants. However, it is not known if these approaches will clinically benefit long-term infection, by establishing a new immunological set-point that may affect the rate of disease progression. Caution is required when using HAART in combination with cytostatic drugs in HIV-1 infection until their impact and long-term safety have been investigated further in larger clinical trials.     

Ruxolitinib and Tofacitinib Are Potent and Selective Inhibitors of HIV-1 Replication and Virus Reactivation In Vitro

The JAK-STAT pathway is activated in both macrophages and lymphocytes upon human immunodeficiency virus type 1 (HIV-1) infection and thus represents an attractive cellular target to achieve HIV suppression and reduced inflammation, which may impact virus sanctuaries. Ruxolitinib and tofacitinib are JAK1/2 inhibitors that are FDA approved for rheumatoid arthritis and myelofibrosis, respectively, but their therapeutic application for treatment of HIV infection was unexplored. Both drugs demonstrated submicromolar inhibition of infection with HIV-1, HIV-2, and a simian-human immunodeficiency virus, RT-SHIV, across primary human or rhesus macaque lymphocytes and macrophages, with no apparent significant cytotoxicity at 2 to 3 logs above the median effective antiviral concentration. Combination of tofacitinib and ruxolitinib increased the efficacy by 53- to 161-fold versus that observed for monotherapy, respectively, and each drug applied alone to primary human lymphocytes displayed similar efficacy against HIV-1 containing various polymerase substitutions. Both drugs inhibited virus replication in lymphocytes stimulated with phytohemagglutinin (PHA) plus interleukin-2 (IL-2), but not PHA alone, and inhibited reactivation of latent HIV-1 at low-micromolar concentrations across the J-Lat T cell latency model and in primary human central memory lymphocytes. Thus, targeted inhibition of JAK provided a selective, potent, and novel mechanism to inhibit HIV-1 replication in lymphocytes and macrophages, replication of drug-resistant HIV-1, and reactivation of latent HIV-1 and has the potential to reset the immunologic milieu in HIV-infected individuals.     

HIV-1 proprotein processing as a target for gene therapy

The central role of endoconvertases and HIV-1 protease (HIV-1 PR) in the processing of HIV proproteins makes the design of specific inhibitors important in anti-HIV gene therapy. Accordingly, we tested native alpha(1) antitrypsin (alpha(1)AT) delivered by a recombinant simian virus-40-based vector, SV(AT), as an inhibitor of HIV-1 proprotein maturation. Cell lines and primary human lymphocytes were transduced with SV(AT) without selection and detectable toxicity. Expression of alpha(1)AT was confirmed by Northern blotting, immunoprecipitation and immunostaining. SV(AT)-transduced cells showed no evidence of HIV-1-related cytopathic effects when challenged with high doses of HIV-1(NL4-3). As measured by HIV-1 p24 assay, SV(AT)-transduced cells were protected from HIV-1(NL4-3) at challenge dose of 40 000 TCID(50) (MOI = 0.04). In addition, peripheral blood lymphocytes treated with SV(AT) were protected from HIV doses challenge up to 40 000 TCID(50) (MOI = 0.04). By Western blot analyses, the delivered alpha(1)AT inhibited cellular processing of gp160 to gp120 and decreased HIV-1 virion gp120. SV(AT) inhibited processing of p55(Gag) as well. Furthermore, high levels of uncleaved p55(Gag) protein were detected in HIV virus particles recovered from SV(AT)-transduced cells lines and primary lymphocytes. Thus, delivering alpha(1)AT using SV(AT) to human lymphocytes strongly inhibits replication of HIV-1, most likely by inhibiting the activities both of the cellular serine proteases involved in processing gp160 and of the aspartyl protease, HIV-1 PR, which cleaves p55(Gag). alpha(1)AT delivered by SV(AT) may represent a novel and effective strategy for gene therapy to interfere with HIV replication, by blocking a stage in the virus replicative cycle that has until now been inaccessible to gene therapeutic intervention.     

Human immunodeficiency virus and hepatitis B virus infection in pregnancy: diagnostic potential of viral genome detection

Hepatitis B virus (HBV) and human immunodeficiency virus (HIV) account for millions of cases of vertical infections worldwide. Laboratory diagnosis is essential for the detection of potentially infectious carriers. HBeAg represents the best serological marker for HBV replication. Since 10% of HBeAg-negative carriers transmit the virus to their children, determination of viral DNA is more reliable for the assessment of the risk to vertical infection. Risk assessment of vertical HIV transmission and monitoring AZT therapy during pregnancy are achieved by determination of HIV-1 viral load and CD4+ cell count. HIV-1 RNA or cDNA detection permits a nearly 100% sensitive diagnosis of congenital HIV infection already 2 weeks after birth. While qualitative HBV DNA determination should be limited only to anti-HBe carriers in order to assess infectiosity, HIV-1 RNA measurement represents in combination with the CD4+ cell count the best prognostic marker for vertical HIV infection and for the follow-up of infected children.