Lab of Immunoregulation•Berkower Lab Weiss Lab -- Angelo Spadaccini-- Angelo Spadaccini -- Russell Vassell -- Russell Vassell -- Yisheng Ni -- Yong He-- Yisheng Ni -- Yong He

– Hong Chen Hong Chen -- Wei Wang -- Wei Wang– Students: Chiraag Patel -- Nidhi GuptaStudents: Chiraag Patel -- Nidhi Gupta Megan RaymondMegan Raymond

Ton Pinar Ton Pinar NIH Rebecca Lynch -- Paul Rebecca Lynch -- Paul

WingfieldWingfield Sumitra Paul Sumitra Paul

• LVBVD

-- Jacqueline Muller, EM-- Jacqueline Muller, EM

• VRC -- Sanjay Phogat-- Sanjay Phogat

Lab of Immunoregulation• Regulatory AreasRegulatory Areas

– Licensed vaccines: Licensed vaccines: approved Hep A/Hep B vaccine approved Hep A/Hep B vaccine – Clinical trials of new vaccines: Clinical trials of new vaccines: reviewed >250 IND documentsreviewed >250 IND documents– Therapeutic vaccines for HIV infection: Therapeutic vaccines for HIV infection: completed review of first phase 3 trial (3000 subjects) completed review of first phase 3 trial (3000 subjects) – Vaccine Policy: Vaccine Policy: Guidance for peptidesGuidance for peptides Eliminating BSE risk in vaccinesEliminating BSE risk in vaccines Interagency committee on select agents ofInteragency committee on select agents of bioterrorismbioterrorism

• Research Focus: Factors affecting vaccine Factors affecting vaccine potency and efficacy, including biology of the potency and efficacy, including biology of the virus and immune response of the hostvirus and immune response of the host

• Our goals: -- To advance the science of AIDS vaccines -- To advance the science of AIDS vaccines

– To improve our expertise and add value at each To improve our expertise and add value at each step of the regulatory processstep of the regulatory process

Weiss Lab Research FocusWeiss Lab Research Focus• HIV VaccinesHIV Vaccines

– Defining conserved neutralizing determinants in Env Defining conserved neutralizing determinants in Env

– Characterizing Env structures as immunogens for eliciting broadly Characterizing Env structures as immunogens for eliciting broadly

neutralizing antibodiesneutralizing antibodies

– Elucidating the mechanism of antibody neutralization Elucidating the mechanism of antibody neutralization

– Assessing neutralization assaysAssessing neutralization assays

• Smallpox VaccinesSmallpox Vaccines

– Dissecting neutralizing antibodies elicited by DryvaxDissecting neutralizing antibodies elicited by Dryvax

– Evaluating role of those antibodies in protection Evaluating role of those antibodies in protection

HIV Vaccines: Major Research HIV Vaccines: Major Research Findings Findings

• Showed that two highly conserved sites in Env fusion intermediate can be targeted Showed that two highly conserved sites in Env fusion intermediate can be targeted for inhibitionfor inhibition

• Designed structure-based strategy for raising antibodies to these conserved sites Designed structure-based strategy for raising antibodies to these conserved sites

• Evaluated the antibodies for neutralizing activity and studied potential barriers to Evaluated the antibodies for neutralizing activity and studied potential barriers to antibody accessantibody access

• Identified Env mutations and potential resistance mechanisms for escaping Identified Env mutations and potential resistance mechanisms for escaping inhibition at these sites inhibition at these sites

HIV Vaccines: Research RelevanceHIV Vaccines: Research Relevance

• New strategies for developing vaccines that New strategies for developing vaccines that induce broadly neutralizing antibodiesinduce broadly neutralizing antibodies

• New methods for characterizing Env immunogensNew methods for characterizing Env immunogens

• Mechanisms of Env escape from inhibitors Mechanisms of Env escape from inhibitors (resistance)(resistance)

• Expertise in neutralizing assays and potential Expertise in neutralizing assays and potential correlates of protectioncorrelates of protection

Smallpox Vaccines: Major Research Smallpox Vaccines: Major Research FindingsFindings

• Demonstrated that a recombinant vaccinia Demonstrated that a recombinant vaccinia protein (A27) elicits potent neutralizing and protein (A27) elicits potent neutralizing and protective antibodies thatprotective antibodies that– Passively protect immunocompromised animalsPassively protect immunocompromised animals

– Augment vaccinia immune globulin (VIG)Augment vaccinia immune globulin (VIG)

• Showed that A27 antibodies are a minor Showed that A27 antibodies are a minor component of antibodies induced by Dryvaxcomponent of antibodies induced by Dryvax

Smallpox Vaccines: Research Smallpox Vaccines: Research RelevanceRelevance

• Understanding the protective response to Dryvax Understanding the protective response to Dryvax will aid in development of new vaccineswill aid in development of new vaccines

• Identifying viral antigens that induce protective Identifying viral antigens that induce protective antibodies that may be maximized in new antibodies that may be maximized in new vaccinesvaccines

• Providing ways to improve therapeutic Providing ways to improve therapeutic immunoglobulins (to augment or replace VIG)immunoglobulins (to augment or replace VIG)

1. Many successful vaccines are virus-like particles

Can we enhance HIV vaccine potency by incorporatingCan we enhance HIV vaccine potency by incorporating gp120 or gp41into virus-like particles?gp120 or gp41into virus-like particles?

2. HIV envelope has conserved and variable antigenic determinants, and it migrates between two forms, which can be described as open and closed.

Can we modify envelope to keep it in the open form? Can we modify envelope to keep it in the open form? This would expose conserved sites and favor the This would expose conserved sites and favor the induction of broadly crossreactive antibodies.induction of broadly crossreactive antibodies.

Berkower Lab Research Focus

Particle Formation

env

226/42 125/205

HBsAg

503

NH2

Summary of Results

• gp120 Particles– Hybrid proteins assemble efficiently into 20-30 nm particles rich in

gp120.– gp120 is in the native conformation, which changes in response to CD4

receptor binding. It functions like gp120 on the virus.

– Immunogenicity: elicits neutralizing antibodies earlier than native gp120, but these are still limited to the immunizing strain.

• Progress since the site visit– gp120 exists in two conformations: unliganded (closed form) or bound to

CD4 (open form). All gp120 vaccines so far have been in the closed form.

– We have identified five structural loops that change position as gp120 changes to the open form. Removing one of the loops favors the open form and exposes the CD4 binding site for antibody binding.

– This mutant will allow us to immunize with the open form and may lead to vaccines that elicit antibodies to conserved neutralizing sites that are normally hidden.

Relevance of Antibody Research for Immunity to HIV

1. HIV-infected patients make broadly crossreactive neutralizing antibodies

2. Monoclonal antibodies derived from these patients target shared neutralizing determinants on gp120 and gp41

3. A cocktail of monoclonals gave the most potent protection ever seen in the macaque challenge model, with sterilizing immunity in most cases.

4. A vaccine that exposes the functional sites targeted by these antibodies would have the best chance of inducing protective immunity.

Impact of Research

1. A successful AIDS vaccine most likely will elicitboth neutralizing antibodies and effector T cells.

2. Antibodies that target essential viral functions, such as receptor binding or viral membrane fusion, can crossreact broadly. 3. Successfully modified forms of gp120, with exposed neutralizing determinants, can lead to immunogens with enhanced vaccine potency. 4. Studies of viral neutralization will help us to evaluate new vaccine candidates and define the correlates of immunity.