Showing papers by "Myron S. Cohen published in 2009"

Genetic identity, biological phenotype, and evolutionary pathways of transmitted/founder viruses in acute and early HIV-1 infection.

Abstract: Identification of full-length transmitted HIV-1 genomes could be instrumental in HIV-1 pathogenesis, microbicide, and vaccine research by enabling the direct analysis of those viruses actually responsible for productive clinical infection. We show in 12 acutely infected subjects (9 clade B and 3 clade C) that complete HIV-1 genomes of transmitted/founder viruses can be inferred by single genome amplification and sequencing of plasma virion RNA. This allowed for the molecular cloning and biological analysis of transmitted/founder viruses and a comprehensive genome-wide assessment of the genetic imprint left on the evolving virus quasispecies by a composite of host selection pressures. Transmitted viruses encoded intact canonical genes ( gag-pol-vif-vpr-tat-rev-vpu-env-nef ) and replicated efficiently in primary human CD4+ T lymphocytes but much less so in monocyte-derived macrophages. Transmitted viruses were CD4 and CCR5 tropic and demonstrated concealment of coreceptor binding surfaces of the envelope bridging sheet and variable loop 3. 2 mo after infection, transmitted/founder viruses in three subjects were nearly completely replaced by viruses differing at two to five highly selected genomic loci; by 12–20 mo, viruses exhibited concentrated mutations at 17–34 discrete locations. These findings reveal viral properties associated with mucosal HIV-1 transmission and a limited set of rapidly evolving adaptive mutations driven primarily, but not exclusively, by early cytotoxic T cell responses.

The first T cell response to transmitted/founder virus contributes to the control of acute viremia in HIV-1 infection

Abstract: Identification of the transmitted/founder virus makes possible, for the first time, a genome-wide analysis of host immune responses against the infecting HIV-1 proteome. A complete dissection was made of the primary HIV-1–specific T cell response induced in three acutely infected patients. Cellular assays, together with new algorithms which identify sites of positive selection in the virus genome, showed that primary HIV-1–specific T cells rapidly select escape mutations concurrent with falling virus load in acute infection. Kinetic analysis and mathematical modeling of virus immune escape showed that the contribution of CD8 T cell–mediated killing of productively infected cells was earlier and much greater than previously recognized and that it contributed to the initial decline of plasma virus in acute infection. After virus escape, these first T cell responses often rapidly waned, leaving or being succeeded by T cell responses to epitopes which escaped more slowly or were invariant. These latter responses are likely to be important in maintaining the already established virus set point. In addition to mutations selected by T cells, there were other selected regions that accrued mutations more gradually but were not associated with a T cell response. These included clusters of mutations in envelope that were targeted by NAbs, a few isolated sites that reverted to the consensus sequence, and bystander mutations in linkage with T cell–driven escape.

Quantitating the Multiplicity of Infection with Human Immunodeficiency Virus Type 1 Subtype C Reveals a Non-Poisson Distribution of Transmitted Variants

Abstract: Identifying the specific genetic characteristics of successfully transmitted variants may prove central to the development of effective vaccine and microbicide interventions. Although human immunodeficiency virus transmission is associated with a population bottleneck, the extent to which different factors influence the diversity of transmitted viruses is unclear. We estimate here the number of transmitted variants in 69 heterosexual men and women with primary subtype C infections. From 1,505 env sequences obtained using a single genome amplification approach we show that 78% of infections involved single variant transmission and 22% involved multiple variant transmissions (median of 3). We found evidence for mutations selected for cytotoxic-T-lymphocyte or antibody escape and a high prevalence of recombination in individuals infected with multiple variants representing another potential escape pathway in these individuals. In a combined analysis of 171 subtype B and C transmission events, we found that infection with more than one variant does not follow a Poisson distribution, indicating that transmission of individual virions cannot be seen as independent events, each occurring with low probability. While most transmissions resulted from a single infectious unit, multiple variant transmissions represent a significant fraction of transmission events, suggesting that there may be important mechanistic differences between these groups that are not yet understood.

Polyclonal B cell differentiation and loss of gastrointestinal tract germinal centers in the earliest stages of HIV-1 infection.

Abstract: Background The antibody response to HIV-1 does not appear in the plasma until approximately 2–5 weeks after transmission, and neutralizing antibodies to autologous HIV-1 generally do not become detectable until 12 weeks or more after transmission. Moreover, levels of HIV-1–specific antibodies decline on antiretroviral treatment. The mechanisms of this delay in the appearance of anti-HIV-1 antibodies and of their subsequent rapid decline are not known. While the effect of HIV-1 on depletion of gut CD4+ T cells in acute HIV-1 infection is well described, we studied blood and tissue B cells soon after infection to determine the effect of early HIV-1 on these cells. Methods and Findings In human participants, we analyzed B cells in blood as early as 17 days after HIV-1 infection, and in terminal ileum inductive and effector microenvironments beginning at 47 days after infection. We found that HIV-1 infection rapidly induced polyclonal activation and terminal differentiation of B cells in blood and in gut-associated lymphoid tissue (GALT) B cells. The specificities of antibodies produced by GALT memory B cells in acute HIV-1 infection (AHI) included not only HIV-1–specific antibodies, but also influenza-specific and autoreactive antibodies, indicating very early onset of HIV-1–induced polyclonal B cell activation. Follicular damage or germinal center loss in terminal ileum Peyer's patches was seen with 88% of follicles exhibiting B or T cell apoptosis and follicular lysis. Conclusions Early induction of polyclonal B cell differentiation, coupled with follicular damage and germinal center loss soon after HIV-1 infection, may explain both the high rate of decline in HIV-1–induced antibody responses and the delay in plasma antibody responses to HIV-1. Please see later in the article for Editors' Summary

Evaluation of azithromycin resistance in Treponema pallidum specimens from madagascar

Abstract: Treponema pallidum resistance to azithromycin has been documented in the US, Canada, and Ireland. We found no evidence of resistance to azithromycin in specimens from 141 patients with syphilitic lesions in Madagascar suggesting resistance is geographically isolated and supporting use of azithromycin as alternative treatment for early syphilis in Madagascar.

Factors Related to Female Sex Workers' Willingness to Utilize VCT Service: A Qualitative Study in Jinan City, Northern China

Abstract: While national HIV prevalence remains low in China, female sex workers (FSWs) have become infected at high rates. Free voluntary HIV counseling and testing (VCT) has been offered in recent years; however, its utilization rate is low. This study explored factors related to FSWs' willingness to utilize a VCT clinic. Qualitative interviews informed by the Ecological Perspective were conducted to interview 17 FSWs and 12 managers from 23 selected entertainment establishments in Jinan, the capital of Shandong province in northern China. While the majority of FSWs professed willingness to use VCT services, they described barriers to actual utilization of services which included: misunderstandings about HIV; low perceived risk and HIV prevalence; mistrust of the free VCT; and especially anxiety about the implications of possible test results. This research suggests that increasing FSWs' utilization of VCT will require increased knowledge of HIV and VCT, and acceptance of testing and on-site VCT services.

Using antiretrovirals to prevent HIV transmission

Abstract: Publisher Summary This chapter describes the ways in which antiretrovirals (ART) can be used for prevention as well as treatment of HIV. ART has drastically reduced HIV-associated mortality and improved the quality of lives of those living with HIV infection. More recently, global initiatives to expand the use of ART in resource poor countries have achieved some degree of success. The transmission of HIV depends on the infectiousness of the host and the susceptibility of the partner. The likelihood of transmission can be described in terms of “efficiency,” which varies greatly by the route of transmission and, for sexual transmission, the details of the sexual behavior. Transmission of HIV by all routes has been most strongly associated with HIV viral load in the blood. The association between HIV viral load and sexual transmission must reflect a correlation between the concentration of HIV in genital secretions and in blood. Antiretroviral agents differ greatly in their ability to penetrate the genital tract. Since highly protein-bound antiretroviral agents achieve lower concentrations in genital tract than in blood plasma, affinity for albumin and a 1–acid glycoprotein may prevent penetration of antiviral agents into genital secretions. There are three ways ART can be used to prevent HIV transmission: by reducing HIV viral load in people who know they are infected, as post-exposure prophylaxis, and as pre-exposure prophylaxis both orally and as a topical microbicide. Antiretroviral therapy will prolong survival, but at the same time will greatly increase the time available for viral transmission and the transmission of resistant isolates. The expanded use of ART for prevention in research, clinical, and casual practice seems inevitable.

Performance of serological tests for syphilis in sexually transmitted diseases clinics in Guangxi Autonomous Region, China: implications for syphilis surveillance and control

Abstract: Background: China is experiencing a growing syphilis epidemic. Individuals are currently screened and cases are confirmed using traditional serological testing methods. Methods: A total of 11 558 serum specimens from patients at 14 sexually transmitted diseases (STD) clinics at provincial, prefecture and county levels in Guangxi Autonomous Region were tested at local clinics using the toluidine red unheated serum test (TRUST) and the SD Bioline Syphilis 3.0 Treponema Pallidum (SD-TP) test and then transported to the National STD Reference Laboratory for TRUST and confirmatory Treponema pallidum particle assay (TPPA) testing. Results: In local clinics, 13.2% of specimens were TRUST positive and 12.8% were TRUST and SD-TP positive. At the Reference Laboratory, 15.4% of specimens were TRUST positive and 11.8% were TRUST and TPPA positive. Local clinics showed a significantly higher prevalence of active syphilis compared with results from the Reference Laboratory (12.8 v. 11.8%, χ2 = 4.59, P = 0.03). The local TRUST tests had consistent results with Reference Laboratory tests qualitatively among 96.2% of the specimens and quantitatively among 95.5% of the specimens. The algorithm of TRUST screening and then SD-TP confirmation among positive TRUST specimens at local STD clinics had 96.6% sensitivity and 99.3% specificity in diagnosing active syphilis compared with the ‘gold standard’ based on TRUST and TPPA positivity at the Reference Laboratory (positive predictive value 95.1% and negative predictive value 99.5%). Conclusion: The TRUST screening and SD-TP confirmation in combination can be used at local STD clinics for the efficient diagnosis of serologically active syphilis. However, continuing capacity building and quality assurance remain critical in ensuring the quality of syphilis diagnosis at local clinics.

Biological activity of 19-nor, 10-keto, 25-hydroxyvitamin D3.

Abstract: 19 nor, 10 keto, 25-hydroxyvitamin D3 (19/10–25OHD3) is a metabolite of 25-OHD3 produced in vitro by various phagocytes including normal human blood monocytes and transformed cell lines, U937 and HL-60. We recently reported that 19/10–25OHD3 induced differentiation of U937 cells. In these studies, 19/10–25OHD3 alone produced no detectable effect on the growth rates, surface adherence, and oxidative metabolism of U937 and HL-60 cells. When combined with lymphocyte-conditioned medium (LCM), 19/10–25OHD3 reduced proliferation, increased surface adherence and stimulated luminol-dependent luminescence (LDL) of the U937 cells. In contrast, the combination of 19/10–25OHD3 and LCM had no effect on the growth of HL-60 cells but did increase the surface adherence and the expression of a complement receptor component. 19/10–25OHD3 competed for tritium-labeled 1,25(OH)2D3 binding to receptors extracted from cultured human skin fibroblasts. This displacement capacity was 600 times weaker than that of unlabeled 1,25(OH)2D3. Incubation of human skin fibroblasts for 24 hr with 19/10–25OHD3 induced 25OHD3-24-hydroxylase activity in the fibroblasts. The inductive potency of 19/10–25OHD3 was 1/50 that of 1,25(OH)2D3. These results demonstrate bioactivity of 19/10–25OHD3 in several systems. At least one of these responses, the induction of 25OHD3-24-hydroxylase, is a receptor-mediated event. Some of the other responses may be independent of the cellular receptor for 1,25(OH)2D3. Interestingly, the potency of 19/10–25OHD3 was highest in the receptor-mediated response (1:50) and lower in the other parameters, ranging from 1: 100 to 1:600 compared to 1,25(OH)2D3. This range of bioactivity in phagocytes and fibroblasts is presently unexplained.

P01-01. The blood transcriptional response to early acute HIV infection is transient and responsive to antiretroviral therapy

Abstract: Address: 1Baylor Institute for Immunology Research, Dallas, TX, USA, 2Baylor Health Care System, Dallas, TX, USA, 3Dept. of Pediatrics, UTSW, Dallas, TX, USA, 4University of North Carolina, Chapel Hill, NC, USA, 5Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA, 6Duke Institute for Genome Sciences and Policy, Duke University, Durham, NC, USA, 7Duke University School of Medicine, Durham, NC, USA and 8Weatherall Institute of Molecular Medicine, Oxford, UK * Corresponding author