Annual and Interim Progress Report Summaries
Principal Investigator: Barton Haynes
Project: Broadly Reactive Neutralizing Antibodies: Novel Strategies for Vaccine Design
Submitted February 1, 2010 (Interim Report)
Our overall goal is to acquire proof of concept data that manipulation of the immunoregulatory controls of B cell immune responses to HIV-1 Env, coupled with enhanced immunogen design, can lead to safe induction of broadly reactive neutralizing antibody responses. We are using a two armed approach to the problem of induction of antibodies that broadly neutralize HIV.
The Kelsoe, Haynes and Thorpe laboratories are developing immunogen formulations that trigger B cells normally tolerant to the desired envelope epitopes and regions. Garnett Kelsoe is determining the origins, development, physiology, and fates of marginal zone, transitional and B1 B cell populations in animal models including mice and non-human primates. Laurent Verkoczy has constructed broadly neutralizing 2F5 and 4E10 human mAb VH +VL knock-in mice. Importantly the mouse models developed by Kelsoe as well as by Verkoczy are now being used for immunization with the group’s lead immunogens to determine the immunoregulatory mechanisms involved in control of these types of antibodies. Haynes is determining the role of tolerance mechanisms, and TLR signaling on control of broadly-reactive B cell activation, and Philip Thorpe is determining the role of lipid binding of anti-HIV antibodies and anti-phosphatidylserine (PS) autoantibodies to protection from HIV infection.
The Harrison, Alam, Spicer, Shaw, Robinson and Hahn laboratories are developing immunogens that are in native conformations and are being tested for induction of neutralizing antibodies. These include HIV Env immunogens with a spectrum of affinities for binding to broadly reactive neutralizing antibodies, and immunogens with low entropic barriers to Mab binding and therefore are thermodynamically stable. Steve Harrison, Bing Chen and Larry Liao have made single chain Fv 4E10 antibodies and whole IgG1 2F5 Mabs with mutations that selectively eliminate gp41 or lipid reactivity. They have demonstrated that both 2F5 and 4E10 require the capacity to bind to lipids to neutralize HIV-1. They are now using the Fvs and Mabs in co-crystallization efforts with trimeric gp120/gp41 constructs. Munir Alam has designed lead candidate gp41 peptide lipid conjugates using 4E10 and 2F5 epitopes peptides, and as well has the lead candidate immunogen liposomes in which the gp41 intermediate form of Chen and Harrison have been incorporated into liposomes with TLR ligands and cytokines. Spicer is studying the lipid-peptide conjugates for their structures by NMR. George Shaw and Beatrice Hahn have constructed HIV-1/HIV-2 chimeras with HIV-2 neutralizing determinants in HIV-1 scaffolds, to study the neutralization of HIV-2 with James Robinson. Dimiter Dimitrov at the NCI has used phage-displayed library technology to isolate a 2F5-like monoclonal antibody from a patient with 2F5-like broadly neutralizing antibodies.