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1.  Longitudinal analysis of intra-host simian immunodeficiency virus recombination in varied tissues of the rhesus macaque model for neuroAIDS 
The Journal of General Virology  2013;94(Pt 11):2469-2479.
Human immunodeficiency virus intra-host recombination has never been studied in vivo both during early infection and throughout disease progression. The CD8-depleted rhesus macaque model of neuroAIDS was used to investigate the impact of recombination from early infection up to the onset of neuropathology in animals inoculated with a simian immunodeficiency virus (SIV) swarm. Several lymphoid and non-lymphoid tissues were collected longitudinally at 21 days post-infection (p.i.), 61 days p.i. and necropsy (75–118 days p.i.) from four macaques that developed SIV-encephalitis or meningitis, as well as from two animals euthanized at 21 days p.i. The number of recombinant sequences and breakpoints in different tissues and over time from each primate were compared. Breakpoint locations were mapped onto predicted RNA and protein secondary structures. Recombinants were found at each time point and in each primate as early as 21 days p.i. No association was found between recombination rates and specific tissue of origin. Several identical breakpoints were identified in sequences derived from different tissues in the same primate and among different primates. Breakpoints predominantly mapped to unpaired nucleotides or pseudoknots in RNA secondary structures, and proximal to glycosylation sites and cysteine residues in protein sequences, suggesting selective advantage in the emergence of specific recombinant sequences. Results indicate that recombinant sequences can become fixed very early after infection with a heterogeneous viral swarm. Features of RNA and protein secondary structure appear to play a role in driving the production of recombinants and their selection in the rapid disease model of neuroAIDS.
PMCID: PMC3809109  PMID: 23963535
2.  HIV-Associated Neuropathogenesis: A Systems Biology Perspective for Modeling and Therapy 
Bio Systems  2014;119:53-61.
Despite the development of powerful antiretroviral drugs, HIV-1 associated neurological disorders (HAND) will affect approximately half of those infected with HIV-1. Combined anti-retroviral therapy (cART) targets viral replication and increases T-cell counts, but it does not always control macrophage polarization, brain infection or inflammation. Moreover, it remains difficult to identify those at risk for HAND. New therapies that focus on modulating host immune response by making use of biological pathways could prove to be more effective than cART for the treatment of neuroAIDS. Additionally, while numerous HAND biomarkers have been suggested, they are of little use without methods for appropriate data integration and a systems-level interpretation. Machine learning, could be used to develop multifactorial computational models that provide clinicians and researchers with the ability to identify which factors (in what combination and relative importance) are considered important to outcome.
PMCID: PMC4112533  PMID: 24732754
HIV; brain; neuropathogenesis; macrophages; microglia; microRNA; data integration; machine learning
3.  HIV Type 1 Genetic Variation in Foreskin and Blood from Subjects in Rakai, Uganda 
The foreskin contains a subset of dendritic cells, macrophages, and CD4+ and CD8+ T cells that may be targets for initial HIV infection in female-to-male sexual transmission of HIV-1. We present analyses comparing HIV-1 sequences isolated from foreskin DNA and serum RNA in 12 heterosexual men enrolled in an adult male circumcision trial performed in Rakai, Uganda. Phylogenetic analysis demonstrated three topologies: (1) little divergence between foreskin and serum, (2) multiple genetic bottlenecks occurring in both foreskin and serum, and (3) complete separation of foreskin and serum populations. The latter tree topology provided evidence that foreskin may serve as a reservoir for distinct HIV-1 strains. Distance and recombination analysis also demonstrated that viral genotypes in the foreskin might segregate independently from the circulating pool of viruses.
PMCID: PMC3380386  PMID: 21902587
4.  Efficient transmission and persistence of low-frequency SIVmac251 variants in CD8-depleted rhesus macaques with different neuropathology 
The Journal of General Virology  2012;93(Pt 5):925-938.
Infection of CD8-depleted rhesus macaques with the genetically heterogeneous simian immunodeficiency virus (SIV)mac251 viral swarm provides a rapid-disease model for simian acquired immune deficiency syndrome and SIV-encephalitis (SIVE). The objective was to evaluate how the diversity of the swarm influences the initial seeding of the infection that may potentially affect disease progression. Plasma, lymphoid and non-lymphoid (brain and lung) tissues were collected from two infected macaques euthanized at 21 days post-infection (p.i.), as well as longitudinal specimens and post-mortem tissues from four macaques followed throughout the infection. About 1300 gp120 viral sequences were obtained from the infecting SIVmac251 swarm and the macaques longitudinal and post-mortem samples. Phylogenetic and amino acid signature pattern analyses were carried out to assess frequency, transmission dynamics and persistence of specific viral clusters. Although no significant reduction in viral heterogeneity was found early in infection (21 days p.i.), transmission and replication of SIV variants was not entirely random. In particular, two distinct motifs under-represented (<4 %) in the infecting swarm were found at high frequencies (up to 14 %) in all six macaques as early as 21 days p.i. Moreover, a macrophage tropic variant not detected in the viral swarm (<0.3 %) was present at high frequency (29–100 %) in sequences derived from the brain of two macaques with meningitis or severe SIVE. This study demonstrates the highly efficient transmission and persistence in vivo of multiple low frequency SIVmac251 founder variants, characterized by specific gp120 motifs that may be linked to pathogenesis in the rapid-disease model of neuroAIDS.
PMCID: PMC3541805  PMID: 22302881
5.  HIV-1 Nef in Macrophage-Mediated Disease Pathogenesis 
Combined anti-retroviral therapy (cART) has significantly reduced the number of AIDS-associated illnesses and changed the course of HIV-1 disease in developed countries. Despite the ability of cART to maintain high CD4+ T-cell counts, a number of macrophage-mediated diseases can still occur in HIV-infected subjects. These diseases include lymphoma, metabolic diseases, and HIV-associated neurological disorders. Within macrophages, the HIV-1 regulatory protein “Nef” can modulate surface receptors, interact with signaling pathways, and promote specific environments that contribute to each of these pathologies. Moreover, genetic variation in Nef may also guide the macrophage response. Herein, we review findings relating to the Nef–macrophage interaction and how this relationship contributes to disease pathogenesis.
PMCID: PMC3544535  PMID: 23215766
cardiovascular disease; dementia; HIV-1 lymphoma; macrophages; Nef
6.  Prediction of R5, X4, and R5X4 HIV-1 Coreceptor Usage with Evolved Neural Networks 
The HIV-1 genome is highly heterogeneous. This variation affords the virus a wide range of molecular properties, including the ability to infect cell types, such as macrophages and lymphocytes, expressing different chemokine receptors on the cell surface. In particular, R5 HIV-1 viruses use CCR5 as a coreceptor for viral entry, X4 viruses use CXCR4, whereas some viral strains, known as R5X4 or D-tropic, have the ability to utilize both coreceptors. X4 and R5X4 viruses are associated with rapid disease progression to AIDS. R5X4 viruses differ in that they have yet to be characterized by the examination of the genetic sequence of HIV-1 alone. In this study, a series of experiments was performed to evaluate different strategies of feature selection and neural network optimization. We demonstrate the use of artificial neural networks trained via evolutionary computation to predict viral coreceptor usage. The results indicate the identification of R5X4 viruses with a predictive accuracy of 75.5 percent.
PMCID: PMC3523352  PMID: 18451438
Computational intelligence; evolutionary computation; artificial neural networks; HIV; AIDS; phenotype prediction; tropism; dual-tropic viruses
7.  Significant Genetic Heterogeneity of the SIVmac251 Viral Swarm Derived from Different Sources 
AIDS Research and Human Retroviruses  2011;27(12):1327-1332.
Infecting rhesus macaques (Macaca mulatta) with the simian immunodeficiency virus (SIV) is an established animal model of human immunodeficiency virus (HIV) pathogenesis. Many studies have used various derivatives of the SIVmac251 viral swarm to investigate several aspects of the disease, including transmission, progression, response to vaccination, and SIV/HIV-associated neurological disorders. However, the lack of standardization of the infecting inoculum complicates comparative analyses. We investigated the genetic diversity and phylogenetic relationships of the 1991 animal-titered SIVmac251 swarm, the peripheral blood mononuclear cell (PBMC) passaged SIVmac251, and additional SIVmac251 sequences derived over the past 20 years. Significant sequence divergence and diversity were evident among the different viral sources. This finding highlights the importance of characterizing the exact source and genetic makeup of the infecting inoculum to achieve controlled experimental conditions and enable meaningful comparisons across studies.
PMCID: PMC3227245  PMID: 21524235
8.  HIV-miR-H1 evolvability during HIV pathogenesis 
Bio Systems  2010;101(2):88-96.
The discovery of microRNAs (miRNAs) in viruses has generated considerable attention into their functional relevance in processes such as cell death, viral proliferation, and oncogenesis. Two early studies found no detectable miRNAs expressed within HIV; however, several studies have verified the existence and function of three HIV miRNAs, most notably HIV-miR-TAR, thus making the earlier results controversial. Although miRNAs are highly conserved within most species, HIV is known to have a high mutation rate, which could contribute to the opposing experimental findings and raises questions about whether all HIV miRNAs are robust enough to maintain their integrity, especially in viral regions prone to insertions and deletions. In addition, could the evolvability of HIV miRNAs contribute to the diversity in HIV disease pathogenesis? To address this question, we examined mutations in 1293 sequences in a suspect HIV miRNA, called miR-H1, derived from a large variety of tissues from seven patients. We found considerable diversity within the structures, including a patient-specific deletion and the potential for the development of new miRNAs as a result of deletions. We also note a potential disease association between a less stable miR-H1 and the development of AIDS-related lymphoma (ARL).
PMCID: PMC3478900  PMID: 20546828
MicroRNA; HIV; Evolution; Pathogenesis
9.  HIV-1 Nef Protein Visits B-Cells via Macrophage Nanotubes: A Mechanism for AIDS-Related Lymphoma Pathogenesis? 
Current HIV research  2010;8(8):638-640.
This letter refers to the recent demonstration that HIV-1 infected macrophages form specialized conduits that connect to B-cells (1). The conduit selectively transports the HIV-1 nef protein, providing nef with numerous means to interfere with cellular processes. Currently, no consideration of the connection between the conduit and the development of AIDS-related lymphoma (ARL) has been offered. ARL is one of the primary causes of death in the HIV-infected population and is related to B-cell proliferation and activation. In this letter we discuss several studies that link HIV-infected macrophages and specific forms of the nef protein to the development of ARL. The conduits discovered by Xu et al. [1] may lead to a better understanding of how HIV infection results in lymphomagenesis.
PMCID: PMC3471533  PMID: 21067513
HIV-1; AIDS-related lymphoma; macrophages; HIV-1 nef protein
10.  Molecular Epidemiology of HIV Type 1 in Singapore and Identification of Novel CRF01_AE/B Recombinant Forms 
AIDS Research and Human Retroviruses  2011;27(10):1135-1137.
To investigate HIV-1 molecular epidemiology in Singapore, we sequenced portions of three regions of the HIV-1 genome (protease HXB2: 2163 to 2620, gp120 HXB2: 6904 to 7628, and gp41 HXB2: 7817 to 8264) from 212 plasma samples collected between February 2008 and August 2009. From these samples, 109 (51.4%) generated interpretable data in all regions. Sixty-one (56.0%) were identified as CRF01_AE, 26 (23.9%) as subtype B and 14 (12.8%) as possible novel recombinant forms. The main novel recombinant pattern, detected in 13 sequences, had subtype B in protease and gp41 and CRF01_AE in gp120. There was intermixing of subtypes within transmission risk groups. However, 85% of subjects infected with the novel recombinant forms self-identified as men who have sex with men or bisexuals compared with only 41% of individuals infected with CRF01_AE and 62% infected with subtype B (p = 0.001).
PMCID: PMC3186691  PMID: 21235306
11.  HIV-1 Phylogenetic analysis shows HIV-1 transits through the meninges to brain and peripheral tissues 
Brain infection by the human immunodeficiency virus type 1 (HIV-1) has been investigated in many reports with a variety of conclusions concerning the time of entry and degree of viral compartmentalization. To address these diverse findings, we sequenced HIV-1 gp120 clones from a wide range of brain, peripheral and meningeal tissues from five patients who died from several HIV-1 associated disease pathologies. High-resolution phylogenetic analysis confirmed previous studies that showed a significant degree of compartmentalization in brain and peripheral tissue subpopulations. Some intermixing between the HIV-1 subpopulations was evident, especially in patients that died from pathologies other than HIV-associated dementia. Interestingly, the major tissue harboring virus from both the brain and peripheral tissues was the meninges. These results show that 1) HIV-1 is clearly capable of migrating out of the brain, 2) the meninges are the most likely primary transport tissues, and 3) infected brain macrophages comprise an important HIV reservoir during highly active antiretroviral therapy.
PMCID: PMC3005076  PMID: 21055482
HIV; Brain; Dementia; Meninges; Viral migration; Macrophages; HIV-associated disease pathologies
12.  HIV-1 Evolutionary Patterns Associated with Pathogenic Processes in the Brain 
Journal of neurovirology  2010;16(3):230-241.
The interplay between pathology and HIV expansion in brain tissues has not been thoroughly assessed in the HAART era. HIV-associated dementia (HAD) is marked by progressive brain infection due to recruitment and migration of macrophages in brain tissues; however, the cellular and viral events occurring prior to HAD development and death are under debate. In this study 66 brain tissues from 11 autopsies were analyzed to assess HIV-1 DNA concentration in brain tissues. In most patients without HAD, it was impossible to amplify HIV-1 from brain tissues. Amplifiable DNA was obtained from three cases of patients on HAART who died due to primary pathology other than HAD: 1) cardiovascular disease, a disease associated with HAART therapy, 2) bacterial infections, including Mycobacterium avium complex, rapid occurrence of extreme dementia and, 3) AIDS-related lymphoma with meningeal involvement. HIV-1 DNA was also amplified from multiple tissues of two HAD patients. Analysis of HIV-1 nef, gp120 and gp41 sequences showed reduced viral evolution within brain tissues for the non-HAD cases relative to patients with clinical and histological HAD. The present study is the first to show a potential correlation between HIV-1 evolutionary patterns in the brain and different neuropathologies.
PMCID: PMC2994721  PMID: 20367240
dementia; atherosclerosis; neuropathology; CNS infection; macrophages; HIV-1 nef; genetic analysis
13.  HIV-1 Nef Protein Structures Associated with Brain Infection and Dementia Pathogenesis 
PLoS ONE  2011;6(2):e16659.
The difference between regional rates of HIV-associated dementia (HAD) in patients infected with different subtypes of HIV suggests that genetic determinants exist within HIV that influence the ability of the virus to replicate in the central nervous system (in Uganda, Africa, subtype D HAD rate is 89%, while subtype A HAD rate is 24%). HIV-1 nef is a multifunctional protein with known toxic effects in the brain compartment. The goal of the current study was to identify if specific three-dimensional nef structures may be linked to patients who developed HAD. HIV-1 nef structures were computationally derived for consensus brain and non-brain sequences from a panel of patients infected with subtype B who died due to varied disease pathologies and consensus subtype A and subtype D sequences from Uganda. Site directed mutation analysis identified signatures in brain structures that appear to change binding potentials and could affect folding conformations of brain-associated structures. Despite the large sequence variation between HIV subtypes, structural alignments confirmed that viral structures derived from patients with HAD were more similar to subtype D structures than to structures derived from patient sequences without HAD. Furthermore, structures derived from brain sequences of patients with HAD were more similar to subtype D structures than they were to their own non-brain structures. The potential finding of a brain-specific nef structure indicates that HAD may result from genetic alterations that alter the folding or binding potential of the protein.
PMCID: PMC3036659  PMID: 21347424
15.  Geographic HIV Type 1 Subtype Distribution in Rakai District, Uganda 
AIDS Research and Human Retroviruses  2009;25(10):1045-1048.
To analyze HIV-1 subtype distribution, sequence analysis was performed on serum specimens obtained in 1994 from the Rakai Health Sciences community cohort in Uganda. Portions of gag-p24 and env-gp41 were sequenced and HIV subtype was determined for 773 subjects residing in 10 community clusters in rural Uganda. Subtypes A (17%) and D (70%) were the most common strains in the population. Subtype distribution varied by geographic region with significantly more subtype A in northern community clusters compared with southern clusters (21% vs. 8%, p < 0.001) and more subtype D in southern clusters compared with northern clusters (78% vs. 65%, p < 0.008). These data illustrate the geographic complexity of subtype variation, which has important implications for HIV-1 vaccine design.
PMCID: PMC2785855  PMID: 19803713
16.  Distinct Patterns of HIV-1 Evolution within Metastatic Tissues in Patients with Non-Hodgkins Lymphoma 
PLoS ONE  2009;4(12):e8153.
Despite highly active antiretroviral therapy (HAART), AIDS related lymphoma (ARL) occurs at a significantly higher rate in patients infected with the Human Immunodeficiency Virus (HIV) than in the general population. HIV-infected macrophages are a known viral reservoir and have been shown to have lymphomagenic potential in SCID mice; therefore, there is an interest in determining if a viral component to lymphomagenesis also exists. We sequenced HIV-1 envelope gp120 clones obtained post mortem from several tumor and non-tumor tissues of two patients who died with AIDS-related Non-Hodgkin's lymphoma (ARL-NH). Similar results were found in both patients: 1) high-resolution phylogenetic analysis showed a significant degree of compartmentalization between lymphoma and non-lymphoma viral sub-populations while viral sub-populations from lymph nodes appeared to be intermixed within sequences from tumor and non-tumor tissues, 2) a 100-fold increase in the effective HIV population size in tumor versus non-tumor tissues was associated with the emergence of lymphadenopathy and aggressive metastatic ARL, and 3) HIV gene flow among lymph nodes, normal and metastatic tissues was non-random. The different population dynamics between the viruses found in tumors versus the non-tumor associated viruses suggest that there is a significant relationship between HIV evolution and lymphoma pathogenesis. Moreover, the study indicates that HIV could be used as an effective marker to study the origin and dissemination of lymphomas in vivo.
PMCID: PMC2780293  PMID: 19997510
17.  Geographic HIV Type 1 Subtype Distribution in Rakai District, Uganda 
AIDS research and human retroviruses  2009;25(10):1045-1048.
To analyze HIV-1 subtype distribution, sequence analysis was performed on serum specimens obtained in 1994 from the Rakai Health Sciences community cohort in Uganda. Portions of gag-p24 and env-gp41 were sequenced and HIV subtype was determined for 773 subjects residing in 10 community clusters in rural Uganda. Subtypes A (17%) and D (70%) were the most common strains in the population. Subtype distribution varied by geographic region with significantly more subtype A in northern community clusters compared with southern clusters (21% vs. 8%, p < 0.001) and more subtype D in southern clusters compared with northern clusters (78% vs. 65%, p < 0.008). These data illustrate the geographic complexity of subtype variation, which has important implications for HIV-1 vaccine design.
PMCID: PMC2785855  PMID: 19803713
18.  Extensive HIV-1 Intra-Host Recombination Is Common in Tissues with Abnormal Histopathology 
PLoS ONE  2009;4(3):e5065.
There is evidence that immune-activated macrophages infected with the Human Immunodeficiency Virus (HIV) are associated with tissue damage and serve as a long-lived viral reservoir during therapy. In this study, we analyzed 780 HIV genetic sequences generated from 53 tissues displaying normal and abnormal histopathology. We found up to 50% of the sequences from abnormal lymphoid and macrophage rich non-lymphoid tissues were intra-host viral recombinants. The presence of extensive recombination, especially in non-lymphoid tissues, implies that HIV-1 infected macrophages may significantly contribute to the generation of elusive viral genotypes in vivo. Because recombination has been implicated in immune evasion, the acquisition of drug-resistance mutations, and alterations of viral co-receptor usage, any attempt towards the successful eradication of HIV-1 requires therapeutic approaches targeting tissue macrophages.
PMCID: PMC2659430  PMID: 19333384
19.  Phylodynamic Analysis of Human Immunodeficiency Virus Type 1 in Distinct Brain Compartments Provides a Model for the Neuropathogenesis of AIDS 
Journal of Virology  2005;79(17):11343-11352.
“Phylodynamic” analysis combines various statistical procedures that can be used to correlate the epidemiological and evolutionary behavior of viral pathogens with the immune system of the host. We utilized this approach to examine human immunodeficiency virus type 1 (HIV-1) gp120 envelope DNA sequences (V1, V2, and V3) isolated from different brain compartments of a T-cell-depleted patient diagnosed with severe HIV-associated dementia at the time of death. In agreement with previous reports, phylogenetic analysis showed distinct virodemes but also revealed a significant amount of viral gene flow among different brain compartments. Local-molecular-clock analysis showed that HIV-1 meninges and temporal lobe subpopulations evolve about 30 and 100 times faster, respectively, than the other viral populations in the brain. However, maximum likelihood codon-based substitution models did not detect any site under significant positive selective pressure, and the main cause of HIV-1 genetic variation appeared to be random genetic drift. Therefore, the higher evolutionary rate in the meninges and temporal lobe could be due to an enhanced infection/expansion rate of macrophages as a consequence of the immune system failure. In conclusion, in this case study, viral infection in the brain progressed with a nonspecific genetic evolution, recurrent migration events, and an expansion of macrophage-tropic sequences. The data suggest that after immune failure newly produced viral variants, which would be rapidly cleared under normal conditions, begin to productively infect macrophages in a “self-amplifying” cycle of infection/inflammatory response that could be at the origin of HIV-associated dementia.
PMCID: PMC1193641  PMID: 16103186

Results 1-19 (19)