Analysis of Host Gene Expression Profile in HIV-1 and HIV-2 Infected T-Cells.

HIV replication is closely regulated by a complex pathway of host factors, many of them being determinants of cell tropism and host susceptibility to HIV infection. These host factors are known to exert a positive or negative influence on the replication of the two major types of HIV, HIV-1 and HIV-2, thereby modulating virus infectivity, host response to infection and ultimately disease progression profiles characteristic of these two types. Understanding the differential regulation of host cellular factors in response to HIV-1 and HIV-2 infections will help us to understand the apparent differences in rates of disease progression and pathogenesis. This knowledge would aid in the discovery of new biomarkers that may serve as novel targets for therapy and diagnosis. The objective of this study was to determine the differential expression of host genes in response to HIV-1/HIV-2 infection. To achieve this, we analyzed the effects of HIV-1 (MN) and HIV-2 (ROD) infection on the expression of host factors in PBMC at the RNA level using the Agilent Whole Human Genome Oligo Microarray. Differentially expressed genes were identified and their biological functions determined. Host gene expression profiles were significantly changed. Gene expression profiling analysis identified a subset of differentially expressed genes in HIV-1 and HIV-2 infected cells. Genes involved in cellular metabolism, apoptosis, immune cell proliferation and activation, cytokines, chemokines, and transcription factors were differentially expressed in HIV-1 infected cells. Relatively few genes were differentially expressed in cells infected with HIV-2.

Seroprevalence of human herpesvirus-8 in HIV-1 infected and uninfected individuals in Cameroon.

We evaluated the prevalence of HHV-8 antibodies in 516 plasma samples collected from HIV positive and negative patients from blood banks and urban areas of Cameroon. Among HIV-1 positive samples, HHV-8 seropositivity rate was 61% based on combined reactivity using both ELISA and IFA techniques. HIV negative samples showed 62% seropositivity rate for HHV-8 antibodies. Our results indicate a high HHV-8 prevalence rate in both HIV infected and uninfected individuals in Cameroon.

Effect of sex steroid hormones on replication and transmission of major HIV subtypes.

BACKGROUND: The HIV epidemic is expanding worldwide with an increasing number of distinct viral subtypes and circulating recombinant forms (CRFs). Out of 34 million adults living with HIV and AIDS, women account for one half of all HIV-1 infections worldwide. These gender differences in HIV pathogenesis may be attributed to sex hormones. Little is known about the role of sex hormone effects on HIV Subtypes pathogenesis. The aim of our study was to determine sex hormone effects on replication and transmissibility of HIV subtypes. METHODS: Peripheral blood mononuclear cells (PBMC) and monocyte derived dendritic cells (MDDC) from male and female donors were infected with HIV subtypes A-D and CRF02_AG, CRF01_AE, MN (lab adapted), Group-O, Group-N and HIV-2 at a concentration of 5ng/ml of p24 or p27. Virus production was evaluated by measuring p24 and p27 levels in culture supernatants. Similar experiments were carried out in the presence of physiological concentrations of sex steroid hormones. R5/X4 expressions measured by flow cytometry and transmissibility was evaluated by transfer of HIV from primary dendritic cells (DC) to autologous donor PBMC. RESULTS: Our results from primary PBMC and MDDC from male and female donors indicate in the absence of physiological concentrations of hormone treatment virus production was observed in three clusters; high replicating virus (subtype B and C), moderate replicative virus (subtype A, D, CRF01_AE, Group_N) and least replicative virus (strain MN). However, dose of sex steroid hormone treatment influenced HIV replication and transmission kinetics in PBMC, DCs and cell lines. Such effects were inconsistent between donors and HIV subtypes. Sex hormone effects on HIV entry receptors (CCR5/CXCR4) did not correlate with virus production. CONCLUSIONS: Subtypes B and C showed higher replication in PBMC from males and females and were transmitted more efficiently through DC to male and female PBMC compared with other HIV-1 subtypes, HIV-1 Group O and HIV-2. These findings are consistent with increased worldwide prevalence of subtype B and C compared to other subtypes. Sex steroid hormones had variable effect on replication or transmission of different subtypes. These findings suggest that subtype, gender and sex hormones may play a crucial role in the replication and transmission of HIV.

Absence of detectable XMRV and other MLV-related viruses in healthy blood donors in the United States.

BACKGROUND: Preliminary studies in chronic fatigue syndrome (CFS) patients and XMRV infected animals demonstrated plasma viremia and infection of blood cells with XMRV, indicating the potential risk for transfusion transmission. XMRV and MLV-related virus gene sequences have also been detected in 4-6% of healthy individuals including blood donors in the U.S. These results imply that millions of persons in the U.S. may be carrying the nucleic acid sequences of XMRV and/or MLV-related viruses, which is a serious public health and blood safety concern. METHODOLOGY/PRINCIPAL FINDINGS: To gain evidence of XMRV or MLV-related virus infection in the U.S. blood donors, 110 plasma samples and 71 PBMC samples from blood donors at the NIH blood bank were screened for XMRV and MLV-related virus infection. We employed highly sensitive assays, including nested PCR and real-time PCR, as well as co-culture of plasma with highly sensitive indicator DERSE cells. Using these assays, none of the samples were positive for XMRV or MLV-related virus. CONCLUSIONS/SIGNIFICANCE: Our results are consistent with those from several other studies, and demonstrate the absence of XMRV or MLV-related viruses in the U.S. blood donors that we studied.

XMRV: usage of receptors and potential co-receptors.

BACKGROUND: XMRV is a gammaretrovirus first identified in prostate tissues of Prostate Cancer (PC) patients and later in the blood cells of patients with Chronic Fatigue Syndrome (CFS). Although XMRV is thought to use XPR1 for cell entry, it infects A549 cells that do not express XPR1, suggesting usage of other receptors or co-receptors. METHODS: To study the usage of different receptors and co- receptors that could play a role in XMRV infection of lymphoid cells and GHOST (GFP- Human osteosarcoma) cells expressing CD4 along with different chemokine receptors including CCR1, CCR2, etc., were infected with XMRV. Culture supernatants and cells were tested for XMRV replication using real time quantitative PCR. RESULTS: Infection and replication of XMRV was seen in a variety of GHOST cells, LNCaP, DU145, A549 and Caski cell lines. The levels of XMRV replication varied in different cell lines showing differential replication in different cell lines. However, replication in A549 which lacks XPR1 expression was relatively higher than DU145 but lower than, LNCaP. XMRV replication varied in GHOST cell lines expressing CD4 and each of the co- receptors CCR1-CCR8 and bob. There was significant replication of XMRV in CCR3 and Bonzo although it is much lower when compared to DU145, A549 and LNCaP. CONCLUSION: XMRV replication was observed in GHOST cells that express CD4 and each of the chemokine receptors ranging from CCR1- CCR8 and BOB suggesting that infectivity in hematopoietic cells could be mediated by use of these receptors.

The influence of drug loading on formulation structure and aerosol performance in carrier based dry powder inhalers.

Previous studies have reported that carrier:drug ratio and carrier size influence the aerosol performance of dry powder inhalation systems. These previous studies were complicated by the heterogeneous nature of the carriers used, making it difficult to define an explicit relationship between parameters and performance. Here, the authors studied the influence of drug loading and carrier size on drug aerosol performance using homogeneous spherical model carriers. Different formulations containing drug (salbutamol sulphate) and carriers (polystyrene beads with median diameters of 82.8µm, 277.5µm and 582.9µm, respectively) were prepared by varying the ratio of carrier to drug (from ∼5:1 to ∼85:1). The surface morphology of the carrier particles and force of adhesion were investigated using atomic force microscopy, while the aerosol performance was evaluated using a multi-stage liquid impinger. The carrier surface morphology for all carrier sizes was homogenous with root-mean square roughness values ≤112nm. No significant difference in the force of adhesion between salbutamol sulphate and the three carrier sizes was observed. Significant differences in aerosol performance of salbutamol sulphate (measured as fine particle dose (FPD) and fraction (FPF)≤5µm) from the carriers were observed. Specifically, as carrier size increased FPF decreased. In comparison, as drug loading increased there was no change in FPF until a critical threshold was exceeded. Such observations suggest that: (A) aerosolisation performance is governed by carrier collisions and (B) when homogeneous carriers are used, the aerosol performance remains constant with respect to drug concentration, until the formulation transitions from an ordered mix to an agglomerated and/or segregated powder bed.

Identification of new, emerging HIV-1 unique recombinant forms and drug resistant viruses circulating in Cameroon.

BACKGROUND: The HIV epidemic in Cameroon is characterized by a high degree of viral genetic diversity with circulating recombinant forms (CRFs) being predominant. The goal of our study was to determine recent trends in virus evolution and emergence of drug resistance in blood donors and HIV positive patients. METHODOLOGY: Blood specimens of 73 individuals were collected from three cities and a few villages in Cameroon and viruses were isolated by co-cultivation with PBMCs. Nested PCR was performed for gag p17 (670 bp) pol (840 bp) and Env gp41 (461 bp) genes. Sequences were phylogenetically analyzed using a reference set of sequences from the Los Alamos database. RESULTS: Phylogenetic analysis based on partial sequences revealed that 65% (n = 48) of strains were CRF02_AG, 4% (n = 3) subtype F2, 1% each belonged to CRF06 (n = 1), CRF11 (n = 1), subtype G (n = 1), subtype D (n = 1), CRF22_01A1 (n = 1), and 26% (n = 18) were Unique Recombinant Forms (URFs). Most URFs contained CRF02_AG in one or two HIV gene fragments analyzed. Furthermore, pol sequences of 61 viruses revealed drug resistance in 55.5% of patients on therapy and 44% of drug naïve individuals in the RT and protease regions. Overall URFs that had a primary HIV subtype designation in the pol region showed higher HIV-1 p24 levels than other recombinant forms in cell culture based replication kinetics studies. CONCLUSIONS: Our results indicate that although CRF02_AG continues to be the predominant strain in Cameroon, phylogenetically the HIV epidemic is continuing to evolve as multiple recombinants of CRF02_AG and URFs were identified in the individuals studied. CRF02_AG recombinants that contained the pol region of a primary subtype showed higher replicative advantage than other variants. Identification of drug resistant strains in drug-naïve patients suggests that these viruses are being transmitted in the population studied. Our findings support the need for continued molecular surveillance in this region of West Central Africa and investigating impact of variants on diagnostics, viral load and drug resistance assays on an ongoing basis.

Absence of detectable xenotropic murine leukemia virus-related virus in plasma or peripheral blood mononuclear cells of human immunodeficiency virus type 1-infected blood donors or individuals in Africa.

BACKGROUND: Since the identification of xenotropic murine leukemia virus-related virus (XMRV) in prostate cancer patients in 2006 and in chronic fatigue syndrome patients in 2009, conflicting findings have been reported regarding its etiologic role in human diseases and prevalence in general populations. In this study, we screened both plasma and peripheral blood mononuclear cells (PBMNCs) collected in Africa from blood donors and human immunodeficiency virus Type 1 (HIV-1)-infected individuals to gain evidence of XMRV infection in this geographic region. STUDY DESIGN AND METHODS: A total of 199 plasma samples, 19 PBMNC samples, and 50 culture supernatants from PBMNCs of blood donors from Cameroon found to be infected with HIV-1 and HIV-1 patients from Uganda were screened for XMRV infection using a sensitive nested polymerase chain reaction (PCR) or reverse transcription (RT)-PCR assay. RESULTS: Using highly sensitive nested PCR or RT-PCR and real-time PCR assays capable of detecting at least 10 copies of XMRV plasmid DNA per reaction, none of the 268 samples tested were found to be XMRV DNA or RNA positive. CONCLUSIONS: Our results failed to demonstrate the presence of XMRV infection in African blood donors or individuals infected with HIV-1. More studies are needed to understand the prevalence, epidemiology, and geographic distribution of XMRV infection worldwide.

Characterization of immune responses to capsid protein p24 of human immunodeficiency virus type 1 and implications for detection.

To further refine our current nanoparticle-based HIV-1 p24 antigen assay, we investigated immune responses to p24 to identify diagnostically significant immune dominant epitopes (IDEs) in HIV-infected human sera, to address cross-reactivity of anti-p24 antibodies to different subtypes, and to identify new biomarkers that distinguish acute from chronic HIV infection for more accurate incidence estimation. We identified two major linear epitope regions, located in the CypA binding loop and adjacent helices and at the end of the C-terminal domain. Most sera (86%) from acutely HIV-1-infected individuals reacted with multiple peptides, while 60% and 30% of AIDS patient samples reacted with multiple and single peptides, respectively. In contrast, 46% and 43% of chronically HIV-1-infected individuals reacted with one and none of the peptides, respectively, and only 11% reacted with multiple p24 peptides, indicating a progression of immune responses from polyclone-like during acute infection to monoclone-like or a nonresponse to linear epitopes during chronic infection. Anti-p24 antibodies (subtype B) show broad cross-reactivity to different HIV-1 subtypes, and the synergistic action of different combinations of anti-HIV antibodies improves capture and detection of divergent HIV-1 subtypes. Our results indicate that the modified peptide immunoassay is sensitive and specific for the rapid identification of HIV-1 p24 IDEs and for investigation of immune responses to p24 during natural HIV-1 infection. The data provide the foundation for development and refinement of new assays for improved p24 antigen testing as future tools for rapid and accurate diagnosis as part of early intervention strategies and estimations of incidence.

Comparative analysis of cell culture and prediction algorithms for phenotyping of genetically diverse HIV-1 strains from Cameroon.

BACKGROUND: With the advent of entry inhibitors, monitoring of viral tropism in the clinical setting is important. Conventional methods are cell-based and lengthy, therefore V3 sequence based prediction algorithms are becoming increasingly attractive as monitoring tools. Here we report a comparative analysis of viral tropism of strains circulating in Cameroon where diverse and emerging variant strains are prevalent. METHODS: Viruses were isolated from 17 HIV positive individuals from three cities in Cameroon. Ghost cell lines expressing either CCR5 or CXCR4 with CD4 or CD4 alone (NIH AIDS Reagent Program) were used to determine co-receptor usage. HIV replication was determined by measuring p24 antigen levels. Plasma viral load (VL) was determined using the Versant bDNA assay. Nucleotide sequencing was performed on the V3 region and sequences were edited, aligned and translated into amino acids as described in the algorithm. Bio-informatics tools based on the 11/25 and charge rule were used to predict co-receptor usage. RESULTS: The majority of patient isolates in our study were CRF02_AG or CRF02_AG containing recombinants. Tropism of these complex viruses based on the cell culture assay was determined to be R5 in 15/17 (88.2%) patients. However, two patient isolates were dual tropic R5X4 and had drug-specific mutations. Of these two patients, one was on antiretroviral treatment with a VL of 20,899 copies/ml and the other was drug-naïve with 141,198 copies/ml. Genotype based prediction was overall in good agreement with phenotype for R5 viruses, where 93% (14/15) of results were comparable, dual tropic viruses being reported as X4 viruses by prediction. CONCLUSION: Our results indicate that most HIV strains in Cameroon were R5 tropic and some harbored drug-resistant mutations. V3 sequence based prediction compared well with cell based assays for R5 strains and may be useful even in settings where highly diverse strains are prevalent.

beta-Estradiol attenuates the anti-HIV-1 efficacy of Stavudine (D4T) in primary PBL.

BACKGROUND: Female hormones are known to play an important role in predisposition for many infectious diseases. Recent work suggests there are gender effects in HIV/AIDS progression. Here we ask whether the sex steroid hormone beta-estradiol affects the replication of HIV-1 or the efficacy of a common anti-retroviral drug, Stavudine (D4T). RESULTS: Human PBL were infected with HIV-1 in the presence or absence of combinations of sex steroid hormones and the anti-retroviral drug, D4T. After seven days in culture, viral supernatants were assayed for HIV-1 p24 protein. beta-estradiol resulted in a modest inhibition of HIV-1 replication of approximately 26%. However, 2 nM beta-estradiol increased the amount of HIV-1 replication in the presence of 50 nM D4T from a baseline of 33% (+/- SE = 5.4) to 74% (+/- SE = 5.4) of control virus levels in the absence of drug. Both results were statistically highly significant (p < 0.001). beta-estradiol did not increase the replication of a D4T-resistant strain of HIV in the presence of D4T. The effects were unlikely to be due to general cell inhibition or toxicity because these concentrations of drug and hormone cause no cytotoxicity in PBL as measured by trypan blue exclusion. CONCLUSION: beta-estradiol inhibited both HIV-1 replication in primary human PBL and the antiretroviral efficacy of D4T in PBL cultures. To optimize antiretroviral drug therapy, it may be necessary to monitor patient hormonal status.

Antibodies against a multiple-peptide conjugate comprising chemically modified human immunodeficiency virus type-1 functional Tat peptides inhibit infection.

We demonstrated recently that selective side-chain modification of functional cysteine-rich (Tat(21-40)) and arginine-rich (Tat(53-68)) domains of the HIV-1 Tat protein blocks pathogenic activities of these peptides while retaining their immunological characteristics. In the present study, we have synthesized a multiple-peptide conjugate system comprising modified Tat(21-40) and Tat(53-68) peptides (HIV-1-Tat-MPC). Immunization of mice with this highly homogeneous 10.7 kDa HIV-1-Tat-MPC synthetic construct induced an effective immune response in mice. The antibodies generated against HIV-1-Tat-MPC efficiently suppressed Tat-induced viral replication and significantly reduced HIV-associated cytopathic effects in human monocytes. These results indicate that epitope-specific antibodies directed against functional sites of Tat protein using non-pathogenic peptides inhibit HIV pathogenesis. The HIV-1-Tat-MPC, therefore, has potential for the development of a safe, effective, and economical therapeutic vaccine to reduce the progression of HIV infection.

Development and evaluation of HIV-1 subtype RNA panels for the standardization of HIV-1 NAT assays.

Multiple nucleic acid-based techniques (NAT) have been implemented for testing blood and plasma donors for HIV-1 RNA which may be detected at an earlier stage of infection when HIV antigen or antibody is absent or below the limit of detection of current assays. The available NAT assays are based on different technologies. In order to evaluate the performance of nucleic acid-based techniques (NAT assays) and to allow accurate comparisons of results from different assays, it is essential to have well characterized specimens with known copy numbers as a standard. For this purpose, a comprehensive study was conducted to develop two HIV-1 RNA reference panels. The first (Panel 1) was prepared using a single specimen from the HIV-1 group M subtype B and consists of panel members with a wide range of HIV-1 RNA copy numbers. Panel 2 consists of 26 members representing HIV-1 group M subtypes A, C, D, E, F, G and groups O and N. For accurate determination of HIV-1 RNA copy numbers of each member of Panel 2, they were analyzed using various testing platforms/technologies available through the cooperation of five independent laboratories participating in the study. A consensus value for HIV RNA copy number was assigned to each member of Panel 2 based on statistical analysis of the data provided by the participants. Both panels could serve as reference panels to be used by manufacturers of HIV NAT tests to evaluate the sensitivity limits of their assays.

Monocytes-macrophages are a potential target in human infection with West Nile virus through blood transfusion.

BACKGROUND: West Nile virus (WNV) transmission by transfusion was documented in 2002. Approximately 80 percent of WNV infections are asymptomatic and 1 percent develop severe neurological illness. In animals, Langerhans-dendritic cells support initial viral replication, followed by replication in lymphoid tissues and dissemination to organs and possibly to the CNS. The cellular tropism of WNV infection after transfusion and the particular human blood cells that sustain viral replication remain largely unknown. Whether primary monocyte-derived macrophages (MDMs) support WNV infection-replication and produce infectious virions, with an in vitro system, was investigated. STUDY DESIGN AND METHODS: Elutriated monocytes (CD33+/CD14+) from suitable blood donors were cultured in the presence of macrophage-colony-stimulating factor, infected with WNV-NY99 at different time points, washed, and cultivated for up to 47 days. Supernatants were tested for WNV replication by TaqMan reverse transcription-polymerase chain reaction (RT-PCR), with primers for the envelope and/or 3'NC regions, and by cDNA-PCR to detect WNV minus-strand RNA and for the presence of functional virions by infectivity assays in Vero cells. RESULTS: RT-PCR TaqMan of supernatants demonstrated productive infection of MDMs. Viral load reached 2 to 5 log above baseline in 3 to 6 days and then declined, with detectable viral replication persisting for up to 47 days. WNV minus-strand RNA was detected in Day 4 cultures, indicating active viral replication. Infected MDM cultures showed no cytopathic changes. Supernatants that were TaqMan-positive for the presence of WNV-infected Vero cells and produced cytopathic effects within 3 to 5 days of culture. CONCLUSION: The susceptibility of monocytes-macrophages to productive infection in vitro is compatible with a potential role in initial WNV replication and propagation after transmission by transfusion.

Evaluation of FDA licensed HIV assays using plasma from Cameroonian blood donors.

Several diagnostic assays for the detection of HIV infection have been approved and licensed by the FDA for blood donor screening. However, the performance of these assays is unknown when testing genetically divergent blood specimens. To evaluate the performance of these assays with diverse HIV strains, we chose to study specimens collected from blood donors in Cameroon where genetic diversity and recombinant variants are prevalent. In this study, we tested 240 human plasma specimens collected from two blood centers in Cameroon. These samples were screened initially in Cameroon for antibody to HIV using a rapid assay. We also performed sequencing to determine subtype. Our evaluation has demonstrated that HIV infection in most HIV plasma samples could be detected by most of the US FDA licensed diagnostic assays. With the exception of a few specimens, HIV-1 p24 antigen was not detected in any of the samples. In addition, some nucleic acid tests (NAT) assays were not able to detect a few serologic reactive samples and all new variants including some CRF02_AG variants.

Seroprevalence of human T cell leukemia virus in HIV antibody-negative populations in rural Cameroon.

Seven hundred forty-seven serum samples collected from humans in 4 separate rural village areas in Cameroon were examined for antibody to human T cell leukemia viruses (HTLVs) by use of an enzyme immunoassay followed by a Western blot assay. Of the 88 serum samples that the enzyme immunoassay found to be repeatedly reactive, the HTLV status of 49 samples was confirmed by Western blot assay to be HTLV type I, and the status of 6 samples was confirmed to be HTLV type II.

HIV type 2 primary isolates induce a lower degree of apoptosis "in vitro" compared with HIV type 1 primary isolates.

To determine whether subtypes of HIV-1 and HIV-2 vary in their ability to induce T cell apoptosis in vitro, human peripheral blood mononuclear cells (PBMC) from healthy donors and CEM.NKR-CCR5 cells were infected with a variety of HIV-1 and HIV-2 isolates in vitro. Apoptotic cell levels and chemokine and cytokine production were analyzed. Significant variations in cytopathic effects following in vitro infection with primary isolates of HIV-1 or HIV-2 subtypes were observed in PBMCs. The percent of apoptotic cells from each individual ranged from 2 to 78% after HIV-1 infection and from 0 to 28% after HIV-2 infection (p < 0.01). We did not observe significant differences in the degree of apoptosis induced among cells infected with different HIV-1 group M subtypes or group O virus, nor among cells infected with different HIV-2 isolates. However, HIV-2 induced significantly lower degree of apoptosis overall in PBMC and CEM.NKR-CC5 cells when compared with HIV-1 subtypes (p < 0.0001). No significant differences were observed in the production of chemokines, such as RANTES, MIP-1alpha, and MIP-1beta, and cytokines, such as TNF-alpha and TNF-beta when PBMC cultures were infected with different HIV-1 subtype viruses, or HIV-2 isolates. In conclusion, HIV-2 isolates induced significantly lower levels of T cell apoptosis in both PBMC and CEM.NKR-CCR5 cells than HIV-1 isolates. No differences in T cell apoptosis levels were seen between different subtypes of HIV-1 group M or group O isolates. This is consistent with the mild clinical course of infection with HIV-2 that has been reported relative to that observed with HIV-1.

Bcl-2 upregulation by HIV-1 Tat during infection of primary human macrophages in culture.

The ability of cells of the human monocyte/macrophage lineage to host HIV-1 replication while resisting cell death is believed to significantly contribute to their ability to serve as a reservoir for viral replication in the host. Although macrophages are generally resistant to apoptosis, interruption of anti-apoptotic pathways can render them susceptible to apoptosis. Here we report that HIV-1(BAL )infection of primary human monocyte-derived macrophages (MDM) upregulates the mRNA and protein levels of the anti-apoptic gene, Bcl-2. Furthermore, this upregulation can be quantitatively mimicked by treating MDM with soluble HIV-1 Tat-86 protein. These results suggest that in infecting cells of the monocyte/macrophage lineage, HIV-1 may be benefiting from additional protection against apoptosis caused by specific upregulation of cellular anti-apoptotic genes.