Background/Rationale: A limited number of persons infected with HIV-1 develop circulating plasma antibodies that potently neutralize a wide variety of HIV-1 isolates. The characteristics and specificities of such antibodies can guide the development of HIV-1 vaccine candidates. Current methods for the study of these antibodies include isolation of antibodies from memory B cells, which may not always reflect the circulating antibodies. Our research has focused on the identification and characterization of broad neutralizing antibodies directly from patient plasma (without potential bias of selection). We have noted particular biochemical signatures that point to a common dominant, acidic epitope that is targeted on the envelope of HIV. Objectives: The specific hypothesis of this proposal is that a shared acidic epitope on the gp120 envelope binds a shared immunoglobulin gene family giving rise to the broad HIV-1 neutralizing response in plasma.
The specific aims of the project are to 1) Directly isolate and sequence the antibodies responsible for the broad neutralization from the plasma of HIV-1 infected individuals with broad neutralization, 2) Define the gene family usage of neutralizing versus non-neutralizing antibodies to test the hypothesis that a shared immunoglobulin gene family is responsible for the broad HIV-1 neutralization response in plasma, 3) Map the corresponding epitope(s) of the broad neutralizing antibodies to test the hypothesis that a shared acidic epitope of gp120 is responsible for the broad HIV-1 neutralization response in plasma. Methods: We have identified 10 patients with broad neutralization, of which 3 will be studied in detail. The affinity purification (antigen, subclass, and light chain specific) and fractionation (free-flow isoelectric focusing) scheme can narrow the antibodies of interest, directly, from the plasma to individual species, which will be tested for broad neutralization. Upon confirmation, the individual antibody bands will be sequenced de novo using LC-MS. Epitope mapping of the new mAbs will be undertaken with Elisa, mutagenesis studies, and X-ray crystallography. Once the epitope is identified, Elisa and mutagenesis studies will be used to test the active fraction o the other 7 individuals to determine if this epitope is responsible for broad neutralization. We wil also define the gene family usage of neutralizing versus non-neutralizing antibodies in 20 patients. Anticipated results will be isolation of new mAbs and the identification of a common acidic epitope that can direct broad HIV-1 neutralization. We have completed enough work on the techniques described herein (as well as each alternative plan) to ensure that the aims are feasible and will be completed. Impact: If our hypothesis proves correct, then the results will be novel in its method, and directl applicable to the study of HIV vaccines. This study will provide a deeper understanding of possibilities of the broad HIV-1 neutralizing response in humans, and it will also have identified a naturally occurring epitope(s) that can be the target of potent cross-clade antibodies against HIV-1 as well as the gene family(ies) responsible.

Public Health Relevance

Rare HIV-infected individuals have antibodies that strongly neutralize many different types of HIV, preventing HIV from infecting cells (which is also how a vaccine works). This project proposes to study the common characteristics of these antibodies and directly isolate them from the blood of these individuals. Once the antibodies are isolated, we will determine their sequence (allowing the antibodies to be easily recreated for further study) and determine which part of the HIV virus these special antibodies target. It is our hope that this research will help in the development of a successful HIV vaccine.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI110259-05
Application #
9603700
Study Section
HIV/AIDS Vaccines Study Section (VACC)
Program Officer
Malaspina, Angela
Project Start
2014-12-01
Project End
2019-11-30
Budget Start
2018-12-01
Budget End
2019-11-30
Support Year
5
Fiscal Year
2019
Total Cost
Indirect Cost
Name
University of Maryland Baltimore
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
188435911
City
Baltimore
State
MD
Country
United States
Zip Code
21201
Sajadi, Mohammad Mohseni; Dashti, Amir; Rikhtegaran Tehrani, Zahra et al. (2018) Identification of Near-Pan-neutralizing Antibodies against HIV-1 by Deconvolution of Plasma Humoral Responses. Cell 173:1783-1795.e14
Stafford, Kristen A; Rikhtegaran Tehrani, Zahra; Saadat, Saman et al. (2017) Long-term follow-up of elite controllers: Higher risk of complications with HCV coinfection, no association with HIV disease progression. Medicine (Baltimore) 96:e7348
So-Armah, Kaku A; Tate, Janet P; Chang, Chung-Chou H et al. (2016) Do Biomarkers of Inflammation, Monocyte Activation, and Altered Coagulation Explain Excess Mortality Between HIV Infected and Uninfected People? J Acquir Immune Defic Syndr 72:206-13
Buckner, Clarisa M; Kardava, Lela; Zhang, Xiaozhen et al. (2016) Maintenance of HIV-Specific Memory B-Cell Responses in Elite Controllers Despite Low Viral Burdens. J Infect Dis 214:390-8
Sajadi, Mohammad M; Farshidpour, Maham; Brown, Eric P et al. (2016) ? Light Chain Bias Associated With Enhanced Binding and Function of Anti-HIV Env Glycoprotein Antibodies. J Infect Dis 213:156-64
Gohain, Neelakshi; Tolbert, William D; Acharya, Priyamvada et al. (2015) Cocrystal Structures of Antibody N60-i3 and Antibody JR4 in Complex with gp120 Define More Cluster A Epitopes Involved in Effective Antibody-Dependent Effector Function against HIV-1. J Virol 89:8840-54