HIV-associated dementia (HAD) affects a significant number of HIV-infected individuals. A lower incidence/occurrence of HAD has been reported in populations with subtype C HIV-1 infections. We previously reported that subtype C HIV-1 Tat protein is defective in monocyte chemotaxis and proposed this as the basis for the reduction in HIV dementia in India. We have generated new evidence for subtype- specificity of HAD using subtype B and C isolates using the SCID HIV encephalitis (HIVE) model in mice. The current proposal includes a series of experiments to delineate the determinants of subtype-specific differences in with a special focus on Tat protein. The proposal attempts to address whether Tat alone governs the subtype differences observed, to identify the critical residues in Tat necessary for HIVE, to examine the importance of the Tat-chemokine nexus in HIVE and finally identify cellular genes specifically induced by subtype B Tat protein using differential gene expression profiling. We propose four specific aims.
In Aim 1, we will examine the hypothesis that Tat gene alone is responsible for the differential ability of subtype B and C HIV-1 isolates to cause HIV dementia by introducing macrophages expressing the respective Tat genes into SCID mouse brains (in the absence of HIV infection) followed by evaluating mice for encephalopathy and cognitive dysfunction.
In Aim 2, we will attempt to identify whether the dicysteine motif of Tat is the sole determinant of subtype-specificity in the HIVE model and in monocyte chemotaxis by creating point mutations in the dicysteine motif and if the results suggest otherwise, will also examine the signature residues in subtype C Tat for their importance in monocyte chemotaxis and HIVE. Importantly, we will examine the variant Tat genes isolated from the infrequently observed dementia cases among HIV-1 infected individuals in India for their role in causing HAD.
In Aim 3, we will examine the role of monocyte chemoattractant protein, MCP-1 and its receptor, CCR2 by first generating gene knockout mice lacking each of these genes respectively in the SCID background followed by the intracranial injection of HIV-1 infected human macrophages. This will allow us to establish the role of chemokines in HIVE as well as dissect the role of these chemokines in the host vs. graft (via gene knockout for the murine genes and siRNA for human macrophages). Finally, we wish to identify the genes induced by HIV-1 Tat B and C proteins upon HIV-1 infection of monocytic cell line THP-1 with a view to delineate the precise pathways that lead to HAD. Proteins encoded by the genes thus identified will first be tested, using antibodies and RNA silencing in a novel in vitro chemotaxis assay we have developed to study monocyte/leukocyte migration in the context of HIV-infected macrophages. HIV-associated dementia (HAD) and other neurological complications associated with HIV-infection are on the rise. Recent reports indicate that certain strains of HIV-1 prevalent outside the US cause a lower incidence of HAD, allowing us to compare US strains to those in the above regions of the world (India). The current application provides evidence that such differences can be reproduced in small, laboratory animals and seeks to delineate the viral genes responsible for HAD.
|Shaked, Iftach; Hanna, David B; Gleißner, Christian et al. (2014) Macrophage inflammatory markers are associated with subclinical carotid artery disease in women with human immunodeficiency virus or hepatitis C virus infection. Arterioscler Thromb Vasc Biol 34:1085-92|
|Rao, Vasudev R; Neogi, Ujjwal; Eugenin, Eliseo et al. (2014) The gp120 protein is a second determinant of decreased neurovirulence of Indian HIV-1C isolates compared to southern African HIV-1C isolates. PLoS One 9:e107074|
|Rao, Vasudev R; Ruiz, Arthur P; Prasad, Vinayaka R (2014) Viral and cellular factors underlying neuropathogenesis in HIV associated neurocognitive disorders (HAND). AIDS Res Ther 11:13|
|Neogi, Ujjwal; Rao, Shwetha D; Bontell, Irene et al. (2014) Novel tetra-peptide insertion in Gag-p6 ALIX-binding motif in HIV-1 subtype C associated with protease inhibitor failure in Indian patients. AIDS 28:2319-22|
|Hanna, Luke Elizabeth; Neogi, Ujjwal; Ranga, Udaykumar et al. (2014) Phylogenetic characterization of six full-length HIV-1 subtype C molecular clones from three patients: identification of rare subtype C strains containing two NF-?B motifs in the long terminal repeat. AIDS Res Hum Retroviruses 30:586-91|
|Rao, Vasudev R; Neogi, Ujjwal; Talboom, Joshua S et al. (2013) Clade C HIV-1 isolates circulating in Southern Africa exhibit a greater frequency of dicysteine motif-containing Tat variants than those in Southeast Asia and cause increased neurovirulence. Retrovirology 10:61|
|Rao, Vasudev R; Sas, Andrew R; Eugenin, Eliseo A et al. (2008) HIV-1 clade-specific differences in the induction of neuropathogenesis. J Neurosci 28:10010-6|