Broadly neutralizing antibodies (bNAbs) may be crucial component of the protective immunity conferred by an effective HIV-1 vaccine. Ab responses in natural HIV-1 infection are overwhelmingly non-neutralizing. However, a fraction of patients do eventually develop exceptionally broad and potent bNAb responses. We hypothesize that a better understanding of the specificities that underlie this broad serum neutralization will enable us to identify the most desirable targets and develop a full spectrum of vaccine design strategies. New epitopes may be particularly amenable to design or attractive by being unusually broad or potent. Researchers have recently accessed various monoclonal bNAbs (mbNAbs) by high throughput functional screening and/or by targeted selection of memory B cells from infected donors who exhibit broad serum NAb responses. However, these efforts remain challenging, in part due to the rarity of desirable memory B cells and the lack of authentic baits to select new specificities. Based on the premise that native Env trimers are the exclusive targets of NAbs, here we propose using virus-like particles (VLPs) bearing only native Env trimers as baits to retrieve novel mbNAbs that will illuminate novel sites of vulnerability.
Our Specific Aims are:
Specific Aim 1 : To investigate monoclonal bNAb relationships on native trimer VLPs. We will determine the binding relationships of various mbNAb pairs by trimer VLP ELISA. Any antagonistic or synergistic combinations we identify could impact the therapeutic or prophylactic applications of mbNAb combinations. Selected mbMAb combinations will be further investigated in neutralization synergy assays.
Specific Aim 2 : To map the specificities of broadly neutralizing sera using native trimer VLPs. We will evaluate the ability of a panel of broadly neutralizing HIV+ sera to inhibit trimer VLP binding by the panel of mbNAbs used in Aim 1. This will allow us to prioritize B cell selections (Aim 3) from donor PBMCs whose sera exhibit novel NAb specificities.
Specific Aim 3 : To rescue mbNAbs using fluorescent trimer VLPs as baits. With an expert collaborator, we will develop methods to use fluorescently labeled trimer VLPs as baits and probe donor PBMCs to label and retrieve mbNAb clones responsible for broad serum neutralization. We will prioritize donors whose sera appear to target unique epitopes from mapping studies in Aim 2.
Specific Aim 4 : To characterize new mbNAbs. We will determine the specificity, breadth and potency of new mbNAbs. We will examine their binding relationships with other mbNAb specificities on the native trimer, as in Aim 1. To better understand their ontogeny, we will also examine their sequences, segment usage and divergence from nearest germline.

Public Health Relevance

The public health relevance of this proposal is to better understand why bNAbs generated in HIV-1-infected individuals are far more effective than any NAbs thus far induced by vaccination. We will focus on expanding the repertoire of completely new specificities. This will provide new knowledge on the vulnerable sites on HIV-1 and impetus to induce similar responses in vaccine setting. New antibodies may also be useful in prophylactic or therapeutic settings, especially if they recognize novel sites on the virus, are potent, broad and/or act in synergy with others.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
7R01AI100790-03
Application #
8841172
Study Section
HIV/AIDS Vaccines Study Section (VACC)
Program Officer
Li, Yen
Project Start
2014-05-01
Project End
2017-04-30
Budget Start
2014-05-01
Budget End
2015-04-30
Support Year
3
Fiscal Year
2014
Total Cost
$263,676
Indirect Cost
$13,676
Name
San Diego Biomedical Research Institute
Department
Type
DUNS #
079166097
City
San Diego
State
CA
Country
United States
Zip Code
92121
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Huang, Jinghe; Kang, Byong H; Pancera, Marie et al. (2014) Broad and potent HIV-1 neutralization by a human antibody that binds the gp41-gp120 interface. Nature 515:138-42
Tong, Tommy; Crooks, Ema T; Osawa, Keiko et al. (2014) Multi-Parameter Exploration of HIV-1 Virus-Like Particles as Neutralizing Antibody Immunogens in Guinea Pigs, Rabbits and Macaques. Virology 456-457:55-69
Bontjer, Ilja; Melchers, Mark; Tong, Tommy et al. (2013) Comparative Immunogenicity of Evolved V1V2-Deleted HIV-1 Envelope Glycoprotein Trimers. PLoS One 8:e67484
Gach, Johannes S; Quendler, Heribert; Tong, Tommy et al. (2013) A human antibody to the CD4 binding site of gp120 capable of highly potent but sporadic cross clade neutralization of primary HIV-1. PLoS One 8:e72054
Tong, Tommy; Osawa, Keiko; Robinson, James E et al. (2013) Topological analysis of HIV-1 glycoproteins expressed in situ on virus surfaces reveals tighter packing but greater conformational flexibility than for soluble gp120. J Virol 87:9233-49
Löving, Robin; Sjöberg, Mathilda; Wu, Shang-Rung et al. (2013) Inhibition of the HIV-1 spike by single-PG9/16-antibody binding suggests a coordinated-activation model for its three protomeric units. J Virol 87:7000-7
Selhorst, Philippe; Grupping, Katrijn; Tong, Tommy et al. (2013) M48U1 CD4 mimetic has a sustained inhibitory effect on cell-associated HIV-1 by attenuating virion infectivity through gp120 shedding. Retrovirology 10:12
Ota, Takayuki; Doyle-Cooper, Colleen; Cooper, Anthony B et al. (2012) Anti-HIV B Cell lines as candidate vaccine biosensors. J Immunol 189:4816-24
Tong, Tommy; Crooks, Ema T; Osawa, Keiko et al. (2012) HIV-1 virus-like particles bearing pure env trimers expose neutralizing epitopes but occlude nonneutralizing epitopes. J Virol 86:3574-87

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