Simian immunodeficiency virus infection in wild-caught chimpanzees from Cameroon

Simian immunodeficiency viruses (SIVcpz) infecting chimpanzees (Pan troglodytes) in west central Africa are the closest relatives to all major variants of human immunodeficiency virus type 1 ([HIV-1]; groups M, N and O), and have thus been implicated as the source of the human infections; however, information concerning the prevalence, geographic distribution, and subspecies association of SIVcpz still remains limited. In this study, we tested 71 wild-caught chimpanzees from Cameroon for evidence of SIVcpz infection. Thirty-nine of these were of the central subspecies (Pan troglodytes troglodytes), and 32 were of the Nigerian subspecies (Pan troglodytes vellerosus), as determined by mitochondrial DNA analysis. Serological analysis determined that one P. t. troglodytes ape (CAM13) harbored serum antibodies that cross-reacted strongly with HIV-1 antigens; all other apes were seronegative. To characterize the newly identified virus, 14 partially overlapping viral fragments were amplified from fecal virion RNA and concatenated to yield a complete SIVcpz genome (9,284 bp). Phylogenetic analyses revealed that SIVcpzCAM13 fell well within the radiation of the SIVcpzPtt group of viruses, as part of a clade including all other SIVcpzPtt strains as well as HIV-1 groups M and N. However, SIVcpzCAM13 clustered most closely with SIVcpzGAB1 from Gabon rather than with SIVcpzCAM3 and SIVcpzCAM5 from Cameroon, indicating the existence of divergent SIVcpzPtt lineages within the same geographic region. These data, together with evidence of recombination among ancestral SIVcpzPtt lineages, indicate long-standing endemic infection of central chimpanzees and reaffirm a west central African origin of HIV-1. Whether P. t. vellerosus apes are naturally infected with SIVcpz requires further study

Conserved presence of G-quadruplex forming sequences in the Long Terminal Repeat Promoter of Lentiviruses

G-quadruplexes (G4s) are secondary structures of nucleic acids that epigenetically regulate cellular processes. In the human immunodeficiency lentivirus 1 (HIV-1), dynamic G4s are located in the unique viral LTR promoter. Folding of HIV-1 LTR G4s inhibits viral transcription; stabilization by G4 ligands intensifies this effect. Cellular proteins modulate viral transcription by inducing/unfolding LTR G4s. We here expanded our investigation on the presence of LTR G4s to all lentiviruses. G4s in the 5'-LTR U3 region were completely conserved in primate lentiviruses. A G4 was also present in a cattle-infecting lentivirus. All other non-primate lentiviruses displayed hints of less stable G4s. In primate lentiviruses, the possibility to fold into G4s was highly conserved among strains. LTR G4 sequences were very similar among phylogenetically related primate viruses, while they increasingly differed in viruses that diverged early from a common ancestor. A strong correlation between primate lentivirus LTR G4s and Sp1/NF\u3baB binding sites was found. All LTR G4s folded: their complexity was assessed by polymerase stop assay. Our data support a role of the lentiviruses 5'-LTR G4 region as control centre of viral transcription, where folding/unfolding of G4s and multiple recruitment of factors based on both sequence and structure may take place

A historical reflection on the discovery of human retroviruses

The discovery of HIV-1 as the cause of AIDS was one of the major scientific achievements during the last century. Here the events leading to this discovery are reviewed with particular attention to priority and actual contributions by those involved. Since I would argue that discovering HIV was dependent on the previous discovery of the first human retrovirus HTLV-I, the history of this discovery is also re-examined. The first human retroviruses (HTLV-I) was first reported by Robert C. Gallo and coworkers in 1980 and reconfirmed by Yorio Hinuma and coworkers in 1981. These discoveries were in turn dependent on the previous discovery by Gallo and coworkers in 1976 of interleukin 2 or T-cell growth factor as it was called then. HTLV-II was described by Gallo's group in 1982. A human retrovirus distinct from HTLV-I and HTLV-II in that it was shown to have the morphology of a lentivirus was in my mind described for the first time by Luc Montagnier in an oral presentation at Cold Spring Harbor in September of 1983. This virus was isolated from a patient with lymphadenopathy using the protocol previously described for HTLV by Gallo. The first peer reviewed paper by Montagnier's group of such a retrovirus, isolated from two siblings of whom one with AIDS, appeared in Lancet in April of 1984. However, the proof that a new human retrovirus (HIV-1) was the cause of AIDS was first established in four publications by Gallo's group in the May 4th issue of Science in 1984

An Assay to Monitor HIV-1 Protease Activity for the Identification of Novel Inhibitors in T-Cells

The emergence of resistant HIV strains, together with the severe side-effects of existing drugs and lack of development of effective anti-HIV vaccines highlight the need for novel antivirals, as well as innovative methods to facilitate their discovery. Here, we have developed an assay in T-cells to monitor the proteolytic activity of the HIV-1 protease (PR). The assay is based on the inducible expression of HIV-1 PR fused within the Gal4 DNA-binding and transactivation domains. The fusion protein binds to the Gal4 responsive element and activates the downstream reporter, enhanced green fluorescent protein (eGFP) gene only in the presence of an effective PR Inhibitor (PI). Thus, in this assay, eGFP acts as a biosensor of PR activity, making it ideal for flow cytometry based screening. Furthermore, the assay was developed using retroviral technology in T-cells, thus providing an ideal environment for the screening of potential novel PIs in a cell-type that represents the natural milieu of HIV infection. Clones with the highest sensitivity, and robust, reliable and reproducible reporter activity, were selected. The assay is easily adaptable to other PR variants, a multiplex platform, as well as to high-throughput plate reader based assays and will greatly facilitate the search for novel peptide and chemical compound based PIs in T-cells

A reflection on HIV/AIDS research after 25 years

Dr. Robert C. Gallo provides a personal reflection on the 25 year history of AIDS

Expanding ART for Treatment and Prevention of HIV in South Africa: Estimated Cost and Cost-Effectiveness 2011-2050

Background: Antiretroviral Treatment (ART) significantly reduces HIV transmission. We conducted a cost-effectiveness analysis of the impact of expanded ART in South Africa. Methods: We model a best case scenario of 90% annual HIV testing coverage in adults 15-49 years old and four ART eligibility scenarios: CD4 count <200 cells/mm3(current practice), CD4 count <350, CD4 count <500, all CD4 levels. 2011-2050 outcomes include deaths, disability adjusted life years (DALYs), HIV infections, cost, and cost per DALY averted. Service and ART costs reflect South African data and international generic prices. ART reduces transmission by 92%. We conducted sensitivity analyses. Results: Expanding ART to CD4 count <350 cells/mm3prevents an estimated 265,000 (17%) and 1.3 million (15%) new HIV infections over 5 and 40 years, respectively. Cumulative deaths decline 15%, from 12.5 to 10.6 million; DALYs by 14% from 109 to 93 million over 40 years. Costs drop $504 million over 5 years and$3.9 billion over 40 years with breakeven by 2013. Compared with the current scenario, expanding to <500 prevents an additional 585,000 and 3 million new HIV infections over 5 and 40 years, respectively. Expanding to all CD4 levels decreases HIV infections by 3.3 million (45%) and costs by $10 billion over 40 years, with breakeven by 2023. By 2050, using higher ART and monitoring costs, all CD4 levels saves$0.6 billion versus current; other ART scenarios cost $9-194 per DALY averted. If ART reduces transmission by 99$17.5 billion. Sensitivity analyses suggest that poor retention and predominant acute phase transmission reduce DALYs averted by 26% and savings by 7%. Conclusion: Increasing the provision of ART to <350 cells/mm3 may significantly reduce costs while reducing the HIV burden. Feasibility including HIV testing and ART uptake, retention, and adherence should be evaluated

25 years of HIV-1 research – progress and perspectives

Twenty-five years after the discovery and isolation of the human immunodeficiency virus by French and American scientists, much progress has been made in basic research, clinical treatment, and public health prevention measures for acquired immunodeficiency syndrome. Here, we summarize, in brief, advances that have been achieved and provide some perspectives on future challenges

Induction of HIV Neutralizing Antibodies against the MPER of the HIV Envelope Protein by HA/gp41 Chimeric Protein-Based DNA and VLP Vaccines

Several conserved neutralizing epitopes have been identified in the HIV Env protein and among these, the MPER of gp41 has received great attention and is widely recognized as a promising target. However, little success has been achieved in eliciting MPER-specific HIV neutralizing antibodies by a number of different vaccine strategies. We investigated the ability of HA/gp41 chimeric protein-based vaccines, which were designed to enhance the exposure of the MPER in its native conformation, to induce MPER-specific HIV neutralizing antibodies. In characterization of the HA/gp41 chimeric protein, we found that by mutating an unpaired Cys residue (Cys-14) in its HA1 subunit to a Ser residue, the modified chimeric protein HA-C14S/gp41 showed increased reactivity to a conformation-sensitive monoclonal antibody against HA and formed more stable trimers in VLPs. On the other hand, HA-C14S/gp41 and HA/gp41 chimeric proteins expressed on the cell surfaces exhibited similar reactivity to monoclonal antibodies 2F5 and 4E10. Immunization of guinea pigs using the HA-C14S/gp41 DNA or VLP vaccines induced antibodies against the HIV gp41 as well as to a peptide corresponding to a segment of MPER at higher levels than immunization by standard HIV VLPs. Further, sera from vaccinated guinea pigs were found to exhibit HIV neutralizing activities. Moreover, sera from guinea pigs vaccinated by HA-C14S/gp41 DNA and VLP vaccines but not the standard HIV VLPs, were found to neutralize HIV pseudovirions containing a SIV-4E10 chimeric Env protein. The virus neutralization could be blocked by a MPER-specific peptide, thus demonstrating induction of MPER-specific HIV neutralizing antibodies by this novel vaccine strategy. These results show that induction of MPER-specific HIV neutralizing antibodies can be achieved through a rationally designed vaccine strategy