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      HIV transmission. Selection bias at the heterosexual HIV-1 transmission bottleneck.

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          Abstract

          Heterosexual transmission of HIV-1 typically results in one genetic variant establishing systemic infection. We compared, for 137 linked transmission pairs, the amino acid sequences encoded by non-envelope genes of viruses in both partners and demonstrate a selection bias for transmission of residues that are predicted to confer increased in vivo fitness on viruses in the newly infected, immunologically naïve recipient. Although tempered by transmission risk factors, such as donor viral load, genital inflammation, and recipient gender, this selection bias provides an overall transmission advantage for viral quasispecies that are dominated by viruses with high in vivo fitness. Thus, preventative or therapeutic approaches that even marginally reduce viral fitness may lower the overall transmission rates and offer long-term benefits even upon successful transmission.

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          Most cited references45

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          Chemokine receptors as HIV-1 coreceptors: roles in viral entry, tropism, and disease.

          In addition to CD4, the human immunodeficiency virus (HIV) requires a coreceptor for entry into target cells. The chemokine receptors CXCR4 and CCR5, members of the G protein-coupled receptor superfamily, have been identified as the principal coreceptors for T cell line-tropic and macrophage-tropic HIV-1 isolates, respectively. The updated coreceptor repertoire includes numerous members, mostly chemokine receptors and related orphans. These discoveries provide a new framework for understanding critical features of the basic biology of HIV-1, including the selective tropism of individual viral variants for different CD4+ target cells and the membrane fusion mechanism governing virus entry. The coreceptors also provide molecular perspectives on central puzzles of HIV-1 disease, including the selective transmission of macrophage-tropic variants, the appearance of T cell line-tropic variants in many infected persons during progression to AIDS, and differing susceptibilities of individuals to infection and disease progression. Genetic findings have yielded major insights into the in vivo roles of individual coreceptors and their ligands; of particular importance is the discovery of an inactivating mutation in the CCR5 gene which, in homozygous form, confers strong resistance to HIV-1 infection. Beyond providing new perspectives on fundamental aspects of HIV-1 transmission and pathogenesis, the coreceptors suggest new avenues for developing novel therapeutic and preventative strategies to combat the AIDS epidemic.
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            Probability of HIV-1 transmission per coital act in monogamous, heterosexual, HIV-1-discordant couples in Rakai, Uganda.

            The probability of HIV-1 transmission per coital act in representative African populations is unknown. We aimed to calculate this probability overall, and to estimate how it is affected by various factors thought to influence infectivity. 174 monogamous couples, in which one partner was HIV-1 positive, were retrospectively identified from a population cohort in Rakai, Uganda. Frequency of intercourse and reliability of reporting within couples was assessed prospectively. HIV-1 seroconversion was determined in the uninfected partners, and HIV-1 viral load was measured in the infected partners. Adjusted rate ratios of transmission per coital act were estimated by Poisson regression. Probabilities of transmission per act were estimated by log-log binomial regression for quartiles of age and HIV-1 viral load, and for symptoms or diagnoses of sexually transmitted diseases (STDs) in the HIV-1-infected partners. The mean frequency of intercourse was 8.9 per month, which declined with age and HIV-1 viral load. Members of couples reported similar frequencies of intercourse. The overall unadjusted probability of HIV-1 transmission per coital act was 0.0011 (95% CI 0.0008-0.0015). Transmission probabilities increased from 0.0001 per act at viral loads of less than 1700 copies/mL to 0.0023 per act at 38 500 copies/mL or more (p=0.002), and were 0.0041 with genital ulceration versus 0.0011 without (p=0.02). Transmission probabilities per act did not differ significantly by HIV-1 subtypes A and D, sex, STDs, or symptoms of discharge or dysuria in the HIV-1-positive partner. Higher viral load and genital ulceration are the main determinants of HIV-1 transmission per coital act in this Ugandan population.
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              Deciphering human immunodeficiency virus type 1 transmission and early envelope diversification by single-genome amplification and sequencing.

              Accurate identification of the transmitted virus and sequences evolving from it could be instrumental in elucidating the transmission of human immunodeficiency virus type 1 (HIV-1) and in developing vaccines, drugs, or microbicides to prevent infection. Here we describe an experimental approach to analyze HIV-1 env genes as intact genetic units amplified from plasma virion RNA by single-genome amplification (SGA), followed by direct sequencing of uncloned DNA amplicons. We show that this strategy precludes in vitro artifacts caused by Taq-induced nucleotide substitutions and template switching, provides an accurate representation of the env quasispecies in vivo, and has an overall error rate (including nucleotide misincorporation, insertion, and deletion) of less than 8 x 10(-5). Applying this method to the analysis of virus in plasma from 12 Zambian subjects from whom samples were obtained within 3 months of seroconversion, we show that transmitted or early founder viruses can be identified and that molecular pathways and rates of early env diversification can be defined. Specifically, we show that 8 of the 12 subjects were each infected by a single virus, while 4 others acquired more than one virus; that the rate of virus evolution in one subject during an 80-day period spanning seroconversion was 1.7 x 10(-5) substitutions per site per day; and that evidence of strong immunologic selection can be seen in Env and overlapping Rev sequences based on nonrandom accumulation of nonsynonymous mutations. We also compared the results of the SGA approach with those of more-conventional bulk PCR amplification methods performed on the same patient samples and found that the latter is associated with excessive rates of Taq-induced recombination, nucleotide misincorporation, template resampling, and cloning bias. These findings indicate that HIV-1 env genes, other viral genes, and even full-length viral genomes responsible for productive clinical infection can be identified by SGA analysis of plasma virus sampled at intervals typical in large-scale vaccine trials and that pathways of viral diversification and immune escape can be determined accurately.
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                Author and article information

                Journal
                Science
                Science (New York, N.Y.)
                American Association for the Advancement of Science (AAAS)
                1095-9203
                0036-8075
                Jul 11 2014
                : 345
                : 6193
                Affiliations
                [1 ] Microsoft Research, Redmond, WA 98052, USA. carlson@microsoft.com ehunte4@emory.edu.
                [2 ] Emory Vaccine Center at Yerkes National Primate Research Center, Emory University, Atlanta, GA 30329, USA.
                [3 ] Ragon Institute of Massachusetts General Hospital, Massachusetts Institute of Technology and Harvard University, Cambridge, MA 02114, USA.
                [4 ] Microsoft Research, Redmond, WA 98052, USA.
                [5 ] Division of Infectious Diseases, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA.
                [6 ] Nuffield Department of Clinical Medicine, University of Oxford, Oxford OX1 7BN, UK. National Institute of Health Research, Oxford Biomedical Research Centre, Oxford OX3 7LE, UK. Oxford Martin School, University of Oxford, Oxford OX1 3BD, UK.
                [7 ] Ragon Institute of Massachusetts General Hospital, Massachusetts Institute of Technology and Harvard University, Cambridge, MA 02114, USA. HIV Pathogenesis Programme, Doris Duke Medical Research Institute, Nelson R. Mandela School of Medicine, University of KwaZulu-Natal, Durban 4013, South Africa. KwaZulu-Natal Research Institute for Tuberculosis and HIV (K-RITH), Nelson R. Mandela School of Medicine, University of KwaZulu-Natal, Durban 4001, South Africa. Max Planck Institute for Infection Biology, D-10117 Berlin, Germany.
                [8 ] Department of Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
                [9 ] International AIDS Vaccine Initiative, London SW10 9NH, UK. Imperial College of Science Technology and Medicine, London SW10 9NH, UK.
                [10 ] International AIDS Vaccine Initiative, San Francisco, CA 94105, USA. Department of Epidemiology and Biostatistics, University of California, San Francisco, San Francisco, CA 94105, USA.
                [11 ] Rwanda-Zambia HIV Research Group: Zambia-Emory HIV Research Project, Lusaka, Zambia.
                [12 ] Microsoft Research, Los Angeles, CA 98117, USA.
                [13 ] HIV Pathogenesis Programme, Doris Duke Medical Research Institute, Nelson R. Mandela School of Medicine, University of KwaZulu-Natal, Durban 4013, South Africa. Department of Paediatrics, University of Oxford, Oxford OX1 3SY, UK.
                [14 ] Rwanda-Zambia HIV Research Group: Zambia-Emory HIV Research Project, Lusaka, Zambia. Department of Pathology and Laboratory Medicine, Emory University, Atlanta, GA 30322, USA. Department of Global Health, Rollins School of Public Health, Emory University, Atlanta, GA 30322, USA.
                [15 ] International AIDS Vaccine Initiative, San Francisco, CA 94105, USA. Microsoft Research, Los Angeles, CA 98117, USA. Department of Paediatrics, University of Oxford, Oxford OX1 3SY, UK.
                [16 ] Emory Vaccine Center at Yerkes National Primate Research Center, Emory University, Atlanta, GA 30329, USA. Rwanda-Zambia HIV Research Group: Zambia-Emory HIV Research Project, Lusaka, Zambia. Department of Pathology and Laboratory Medicine, Emory University, Atlanta, GA 30322, USA. carlson@microsoft.com ehunte4@emory.edu.
                Article
                345/6193/1254031 NIHMS646325
                10.1126/science.1254031
                4289910
                25013080
                2fcc65c6-08ed-4dfb-b9f5-58c2d55130eb
                History

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