Structural and functional studies of CCAAT/enhancer binding sites within the human immunodeficiency virus type 1 subtype C LTR.

Human immunodeficiency virus type 1 (HIV-1) subtype C, which is most predominant in sub-Saharan Africa as well as in Asia and India, is the most prevalent subtype worldwide. A large number of transcription factor families have been shown to be involved in regulating HIV-1 gene expression in T lymphocytes and cells of the monocyte-macrophage lineage. Among these, proteins of the CCAAT/enhancer binding protein (C/EBP) family are of particular importance in regulating HIV-1 gene expression within cells of the monocytic lineage during the course of hematologic development and cellular activation. Few studies have examined the role of C/EBPs in long terminal repeat (LTR)-directed viral gene expression of HIV-1 subtypes other than subtype B. Within subtype B viruses, two functional C/EBP sites located upstream of the TATA box are required for efficient viral replication in cells of the monocyte-macrophage lineage. We report the identification of three putative subtype C C/EBP sites, upstream site 1 and 2 (C-US1 and C-US2) and downstream site 1 (C-DS1). C-US1 and C-DS1 were shown to form specific DNA-protein complexes with members of the C/EBP family (C/EBPα, ß, and δ). Functionally, within the U-937 monocytic cell line, subtype B and C LTRs were shown to be equally responsive to C/EBPß-2, although the basal activity of subtype C LTRs appeared to be higher. Furthermore, the synergistic interaction between C/EBPß-2 and Tat with the subtype C LTR was also observed in U-937 cells as previously demonstrated with the subtype B LTR.

Mortality among HIV-Infected Patients in Resource Limited Settings: A Case Controlled Analysis of Inpatients at a Community Care Center.

PROBLEM STATEMENT: Despite massive national efforts to scale up Antiretroviral Therapy (ART) access in India since 2004, the AIDS death rate was 17.2 per 100,000 persons during 2003-2005. In the era of HAART in resource poor settings, it is imperative to understand and address the causes of AIDS related mortality. This collaborative study aimed at defining the predictors of mortality among people living with HIV/AIDS (PLHA) admitted during 2003-2005 to the Freedom Foundation (FF) Care and Support facility, Bangalore, India. APPROACH: Fifty consecutively selected HIV-infected patients who died during the study period and 50 HIV-infected patients matched by age, gender, route of transmission, nutrition status and stage of disease who survived at least 12 months post-ART were included in this study. The impact on mortality by factors such as: Hemoglobin, CD4+T lymphocyte counts, weight loss and Opportunistic Infections (OIs) were studied. Statistical analyses were done by Chi-square, Fisher's Exact Test, Kaplan-Meier and multivariate logistic regression. RESULTS: Recurrent diarrhea was a significant risk factor for mortality (OR = 12.25, p = 0.004), followed by a diagnosis of pulmonary tuberculosis (TB) at first admission (OR = 4.86) while TB in general also negatively impacted survival (p = 0.002). Though not statistically significant, Pneumocystis carinii pneumonia, Cryptococcal meningitis and Toxoplasmosis also negatively affected survival. Mortality was high among those not on HAART (81%) while it was significantly reduced (28%) among those on HAART (p<0.001). Patients who died had elevated liver enzymes (p = 0.027) and significant weight loss (p = 0.012). Mortality was high among patients irregular with their medical follow-up (p<0.001). CONCLUSION: Interventions that facilitate early OI diagnosis and treatment especially diarrhea and TB may reduce mortality in HIV. HAART alone without proper OI management and nutrition did not prevent mortality among PLHA. In resource poor settings, it becomes imperative to focus on low cost tools and increased capacity building along with regular clinical follow-up for diagnosis and early treatment of OIs. Further studies are warranted to explore benefits of initiating HAART earlier than currently recommended.

Molecular Mechanisms of Neurodegenerative Diseases Induced by Human Retroviruses: A Review.

PROBLEM STATEMENT: Infection with retroviruses such as human immunodeficiency virus type 1 (HIV-1) and human T cell leukemia virus type 1 (HTLV-1) have been shown to lead to neurodegenerative diseases such as HIV-associated dementia (HAD) or neuroAIDS and HTLV-1-Associated Myelopathy/Tropical Spastic Paraparesis (HAM/TSP), respectively. APPROACH: HIV-1-induced neurologic disease is associated with an influx of HIV-infected monocytic cells across the blood-brain barrier. Following neuroinvasion, HIV-1 and viral proteins, in addition to cellular mediators released from infected and uninfected cells participate in astrocytic and neuronal dysregulation, leading to mild to severe neurocognitive disorders. RESULTS: The molecular architecture of viral regulatory components including the Long Terminal Repeat (LTR), genes encoding the viral proteins Tat, Vpr and Nef as well as the envelope gene encoding gp120 and gp41 have been implicated in 'indirect' mechanisms of neuronal injury, mechanisms which are likely responsible for the majority of CNS damage induced by HIV-1 infection. The neuropathogenesis of HAM/TSP is linked, in part, with both intra-and extracellular effectors functions of the viral transactivator protein Tax and likely other viral proteins. Tax is traditionally known to localize in the nucleus of infected cells serving as a regulator of both viral and cellular gene expression. CONCLUSION/RECOMMENDATIONS: However, recent evidence has suggested that Tax may also accumulate in the cytoplasm and be released from the infected cell through regulated cellular secretion processes. Once in the extracellular environment, Tax may cause functional alterations in cells of the peripheral blood, lymphoid organs and the central nervous system. These extracellular biological activities of Tax are likely very relevant to the neuropathogenesis of HTLV-1 and represent attractive targets for therapeutic intervention.