In addition to neutralization, antibodies can mediate a variety of Fc-dependent effector functions and defining the role of these in vivo could be critical to determine the antibody response or combination of responses that offer the most optimal protection against HIV exposure. Using the SHIV/macaque model and the broadly neutralizing human lgG1 b12 antibody, we have demonstrated that interaction with Fc gamma receptors (FcyRs) plays an important role in IgG-mediated protection. We have investigated the specificity of this interaction in more detail and recently showed that FcYRIila-mediated ADCC may be less important than commonly thought. In ongoing studies, we are performing an in vivo investigation of the role of FcyRiia- mediated phagocytosis in antibody protection and are confident that we will soon have a clear picture of which FcyRs and corresponding effector functions contribute to lgG1 b12-mediated protection. To expand our investigation and gain a quantitative assessment of effector function contribution to protection, we propose to investigate additional antibody specificities and isotypes in a fully primatized model.
The specific aims are: (1) To determine the magnitude and nature of effector function contribution to protection against mucosal SHIV challenge by the highly potent broadly neutralizing antibody PGT121 as a fully primatized antibody, (2) To determine the importance of antibody isotype in protection against mucosal SHIV challenge by comparing topically administered primatized secretory IgA (SIgA) PGT121 to IgG PGT121, and (3) To correlate neutralization, extra-neutralizing properties and epitope availability with in vivo protection for neutralizing and non-neutralizing antibodies.

Public Health Relevance

Understanding antibody-mediated protection against HIV is crucial for vaccine design. The significance of this project is that it allows for a direct investigation of the antibody properties that contribute to protection in vivo. Neutralization is a well-established and highly desirable property, but accumulating evidence strongly suggests that Fc-mediated effector functions also play an important role in antibody-mediated protection in vivo. In vaccine design, the main problem has been creating immunogens that elicit broadly neutralizing antibodies and many laboratories, including our own, have efforts in this area. If we can correlate protection with in vitro assays measuring Fc-mediated effector function, perhaps in addition to neutralization, we would then be able to determine the type of antibody responses that will provide greatest benefit in the context of a vaccine.

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 #
5R37AI055332-13
Application #
8994252
Study Section
Special Emphasis Panel (NSS)
Program Officer
Malaspina, Angela
Project Start
2003-05-15
Project End
2019-01-31
Budget Start
2016-02-01
Budget End
2017-01-31
Support Year
13
Fiscal Year
2016
Total Cost
Indirect Cost
Name
Scripps Research Institute
Department
Type
DUNS #
781613492
City
La Jolla
State
CA
Country
United States
Zip Code
92037
Moldt, Brian; Le, Khoa; Carnathan, Diane G et al. (2016) Neutralizing antibody affords comparable protection against vaginal and rectal SHIV challenge in macaques. AIDS :
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von Bredow, Benjamin; Arias, Juan F; Heyer, Lisa N et al. (2016) Comparison of Antibody-Dependent Cell-Mediated Cytotoxicity and Virus Neutralization by HIV-1 Env-Specific Monoclonal Antibodies. J Virol 90:6127-6139
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Trist, Halina M; Tan, Peck Szee; Wines, Bruce D et al. (2014) Polymorphisms and interspecies differences of the activating and inhibitory Fc?RII of Macaca nemestrina influence the binding of human IgG subclasses. J Immunol 192:792-803
Barouch, Dan H; Whitney, James B; Moldt, Brian et al. (2013) Therapeutic efficacy of potent neutralizing HIV-1-specific monoclonal antibodies in SHIV-infected rhesus monkeys. Nature 503:224-8
Jaworski, J Pablo; Kobie, James; Brower, Zachary et al. (2013) Neutralizing polyclonal IgG present during acute infection prevents rapid disease onset in simian-human immunodeficiency virus SHIVSF162P3-infected infant rhesus macaques. J Virol 87:10447-59
Poignard, Pascal; Moldt, Brian; Maloveste, Karla et al. (2012) Protection against high-dose highly pathogenic mucosal SIV challenge at very low serum neutralizing titers of the antibody-like molecule CD4-IgG2. PLoS One 7:e42209

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