Although substantial progress has been made on understanding the mechanism of HIV-1 entry into cells, much less is known about the process of virus transmission in vivo. What structural and functional properties of the viral Env protein differentiate the transmitted virus from other variants and facilitate transmission across mucosal surfaces? In this application, we propose to characterize genetically and biologically HIV-1 virus populations isolated from both the donor and recipient immediately following a transmission event in a unique cohort of discordant couples in Zambia. These studies will provide a unique opportunity to investigate the virologic determinants of heterosexual transmission specified by the variable regions of gp120 in biologically relevant viral envelope genes using samples from a large, well-characterized discordant couple cohort that represents the predominant subtype (C) of HIV-1 worldwide. Our hypothesis is that the extreme genetic bottleneck that we have observed, which appears to select for viruses with more compact, neutralization sensitive envelope glycoproteins selects for a virus, which has biological properties that confer unique advantages for transmission and establishment of infection. Partners in concordantly positive couples, particularly those where both are infected by different viruses, are at high risk for superinfection and subsequent virus recombination. We hypothesize that risk of superinfection will depend on virus diversity, will be enhanced by acute infection in one partner, will reflect an inability to immunologically defend against the incoming virus, and that studies of these events will inform on the breadth of protection conferred by immunity to natural infection. For these studies we will follow prospectively, in both Rwanda and Zambia, both partners of couples where we have documented infection of the seronegative partner by a genetically unrelated virus from that in their spouse and monitor for superinfection. Specifically we will: 1. Determine which biological properties of subtype C newly transmitted variants could facilitate establishment of infection in a new host and correlate these with structural features of Env that characterize these isolates, 2. Determine whether a genetic bottleneck occurs in the genital compartment of subtype C infected donor partners or if there is a biological restriction of the transmitted virus population in the genital compartment of the recipients, and 3. Determine the frequency, kinetics and the virologic and immunologic ramifications of HIV superinfection in both partners following acute/early infection. The results of the proposed studies, which are aimed at characterizing the biological properties of newly infecting HIV-1, the origin of the genetic bottleneck observed in acutely infected individuals, and the details and consequences of HIV-1 superinfection, will enhance our understanding of the heterosexual transmission process and will yield novel information that is critical to the design and testing of globally effective vaccine candidates.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Method to Extend Research in Time (MERIT) Award (R37)
Project #
5R37AI051231-11
Application #
8240102
Study Section
AIDS Molecular and Cellular Biology Study Section (AMCB)
Program Officer
Sharma, Opendra K
Project Start
2002-03-15
Project End
2013-03-31
Budget Start
2012-04-01
Budget End
2013-03-31
Support Year
11
Fiscal Year
2012
Total Cost
$832,606
Indirect Cost
$311,729
Name
Emory University
Department
Pathology
Type
Schools of Medicine
DUNS #
066469933
City
Atlanta
State
GA
Country
United States
Zip Code
30322
Haddad, Lisa B; Wall, Kristin M; Kilembe, William et al. (2018) Bacterial vaginosis modifies the association between hormonal contraception and HIV acquisition. AIDS 32:595-604
Joseph Davey, Dvora Leah; Wall, Kristin M; Kilembe, William et al. (2018) Difficult decisions: Evaluating individual and couple-level fertility intentions and HIV acquisition among HIV serodiscordant couples in Zambia. PLoS One 13:e0189869
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Wall, Kristin M; Kilembe, William; Vwalika, Bellington et al. (2017) Risk of heterosexual HIV transmission attributable to sexually transmitted infections and non-specific genital inflammation in Zambian discordant couples, 1994-2012. Int J Epidemiol 46:1593-1606
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Joseph Davey, Dvora; Kilembe, William; Wall, Kristin M et al. (2017) Risky Sex and HIV Acquisition Among HIV Serodiscordant Couples in Zambia, 2002-2012: What Does Alcohol Have To Do With It? AIDS Behav 21:1892-1903
Sutherland, Katherine A; Collier, Dami A; Claiborne, Daniel T et al. (2016) Wide variation in susceptibility of transmitted/founder HIV-1 subtype C Isolates to protease inhibitors and association with in vitro replication efficiency. Sci Rep 6:38153

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