Despite enormous efforts, no effective vaccine is currently available against HIV/AIDS. This is largely due to the virus's ability to evade neutralizing antibodies. The trimeric HIV envelope glycoprotein gp160 (HIV Env), which is exposed to the host immune response on the surface of the virion, effectively conceals epitopes from antibodies while maintaining its ability to promote viral entry. The few exposed antibody-binding sites are structurally unstable and sustain substantial sequence variability. Consequently, few broadly neutralizing antibodies have been identified. Here we will develop single molecule Fluorescence Resonance Energy Transfer (smFRET) imaging to monitor the conformational landscape of individual native Env molecules on the surface of an HIV virus. We will apply new enzymatic methods to introduce organic fluorophores into HIV Env at positions that don't interfere with infectivity. The placement of two dyes within one Env molecule will allow the application of smFRET to report conformational changes of the unliganded HIV Env from various angles. Following the characterization of the unliganded HIV Env, we will determine how its conformation dynamics change in response to receptor and antibody binding. Our approach will identify critical conformational states of HIV Env that should be targeted for vaccine development, reveal the molecular mechanism underlying immune evasion, and understand the potency of existing neutralizing antibodies.

Public Health Relevance

This application proposes the development of single-molecule Fluorescence Resonance Energy Transfer (smFRET) imaging to monitor the conformational landscape of individual trimeric HIV Env molecules on the surface of native HIV viruses. smFRET technology has the potential to elucidate the mechanism of immune evasion and antibody neutralization, and will aid in the rational design of vaccines directed against HIV Env.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Exploratory/Developmental Grants (R21)
Project #
5R21AI100696-02
Application #
8607498
Study Section
HIV/AIDS Vaccines Study Section (VACC)
Program Officer
Sharma, Opendra K
Project Start
2013-02-01
Project End
2015-01-31
Budget Start
2014-02-01
Budget End
2015-01-31
Support Year
2
Fiscal Year
2014
Total Cost
$188,651
Indirect Cost
$39,199
Name
Yale University
Department
Microbiology/Immun/Virology
Type
Schools of Medicine
DUNS #
043207562
City
New Haven
State
CT
Country
United States
Zip Code
06520
Munro, James B; Mothes, Walther (2014) The HIV-1 Env trimer in HD. Structure 22:935-6
Pancera, Marie; Zhou, Tongqing; Druz, Aliaksandr et al. (2014) Structure and immune recognition of trimeric pre-fusion HIV-1 Env. Nature 514:455-61
Munro, James B; Gorman, Jason; Ma, Xiaochu et al. (2014) Conformational dynamics of single HIV-1 envelope trimers on the surface of native virions. Science 346:759-63