The Structural Biology Section (SBS) seeks to apply structural biology to the development of an effective HIV-1 vaccine. Despite the enormous potential of atomic-level design—successfully used, for example, in the development of potent drugs against the HIV-1 protease—current vaccine development makes little use of atomic-level information. We are trying to change this.
One area in which we and others have already made an impact is in understanding how HIV-1 is able to evade the humoral immune system. Determination of the structure of the HIV-1 gp120 envelope glycoprotein (Kwong 1998 Nature 393, 648-659), provided a physical map of the primary target of neutralizing antibodies against HIV-1 and showed how gp120 conformational diversity can prevent antibody-mediated neutralization (Kwong 2002 Nature 420, 678-682) and how N-linked carbohydrates can form an "evolving glycan shield" (Wei 2003 Nature 422, 307-312). These and other studies—including the determination of the crystal structure of the entire spike ectodomain (Pancera 2014 Nature 514, 455-461)—have led to an understanding of the molecular trickery that protects HIV-1 from the humoral immune response.
A second area in which we and others have made an impact is in understanding how human antibodies neutralize diverse HIV-1 isolates. The VRC01 antibody uses mimicry of the CD4 receptor to neutralize over 90 percent of HIV-1 isolates, though the inability of germline versions of VRC01 to bind to HIV-1 Env and its extraordinary level of somatic hypermutation suggest roadblocks to eliciting similar antibodies (Zhou 2010 Science 329, 811-817). Antibodies that bind the V1V2-region of HIV-1 such as CAP256-VRC26, by contrast, use an anionic loop formed by recombination and neutralize at much lower levels of somatic hypermutation (Doria-Rose 2014 Nature 509, 55-62).
But can one use structural biology in vaccine design? Currently, we are following three lines of investigation.
One line involves understanding the B cell pathways that produce broadly neutralizing antibodies and seeking to replicate their development. We’ve observed select broadly neutralizing antibodies to develop similarly in multiple donors (e.g., Wu 2011 Science 333, 1593-1602; Zhou 2013 Immunity 39, 245-258; Bonsignori 2011 J. Virol. 85, 9998-10009; Doria-Rose 2014 Nature 509, 55-62) suggesting that—for select antibodies—a common set of immunogens might spur the induction and maturation of similar antibodies in the general population.
A second line involves the precise delineation of functional constraints to identify potential footholds of conservation and exposure. One functional constraint involves receptor binding—with the site on HIV-1 Env involved in binding the CD4 receptor providing a “supersite of vulnerability.” Analysis of recognition of the CD4 supersite in 14 donors suggest that steric access to the CD4 supersite is a primary physical constraint limiting antibody recognition (Zhou 2015 Cell 161, 1280-1292). We are now following up on these and other clues, such as from llama VHH recognition, which indicate that removable of just a few N-linked glycans around the CD4 supersite might allow sufficient steric access to stimulate the induction of broadly neutralizing CD4-binding-site-directed antibodies.
A third line involves the structure-based engineering of the trimeric spike ectodomain into nanoparticles with the ability to stimulate the induction of broadly neutralizing antibodies. The success of this line of investigation depends in part on the design of spike mimics, which are specific for broadly neutralizing antibodies and not recognized by the non- or poorly neutralizing antibodies that typically dominant the humoral immune response (Kwong 2015 NSMB 22, 522-531). We’ve found that Env requirements for cleavage could be substituted by a flexible linker (e.g., Georgiev 2015 J. Virol. 89, 5318-5329) and are working to produce HIV-1 Env nanoparticles of appropriate antigenicity.
While structure-based vaccine development with HIV-1 is proceeding, we have also been working to test our structure-based approach with other viral pathogens. Recently, we engineered a promising vaccine antigen against respiratory syncytial virus (RSV), the leading cause of hospitalization for children under five years of age. Our “conformational fixation” approach focused on a metastable neutralization-sensitive site called antigenic site Ø (zero), at the membrane-distal apex of the RSV fusion (F) glycoprotein. Immunization of mice and nonhuman primates with a site Ø-stabilized version of RSV F (called DS-Cav1) elicited antibodies many times the protective threshold (McLellan 2013 Science 342, 592-598).
We are now working to apply the insights gleaned from our RSV work to HIV-1.
Dr. Kwong joined the VRC as chief of the Structural Biology Section in the Laboratory of Virology in 2001. Dr. Kwong comes to the Washington area from New York City, where he conducted research in the department of biochemistry and molecular biophysics at Columbia University.
Kwon YD, Pancera M, Acharya P, Georgiev IS, Crooks ET, Gorman J, Joyce MG, Guttman M, Ma X, Narpala S, Soto C, Terry DS, Yang Y, Zhou T, Ahlsen G, Bailer RT, Chambers M, Chuang GY, Doria-Rose NA, Druz A, Hallen MA, Harned A, Kirys T, Louder MK, O'Dell S, Ofek G, Osawa K, Prabhakaran M, Sastry M, Stewart-Jones GB, Stuckey J, Thomas PV, Tittley T, Williams C, Zhang B, Zhao H, Zhou Z, Donald BR, Lee LK, Zolla-Pazner S, Baxa U, Schön A, Freire E, Shapiro L, Lee KK, Arthos J, Munro JB, Blanchard SC, Mothes W, Binley JM, McDermott AB, Mascola JR, Kwong PD. Crystal structure, conformational fixation and entry-related interactions of mature ligand-free HIV-1 Env. Nat Struct Mol Biol. 2015 Jul;22(7):522-31.
Pancera M, Zhou T, Druz A, Georgiev IS, Soto C, Gorman J, Huang J, Acharya P, Chuang GY, Ofek G, Stewart-Jones GB, Stuckey J, Bailer RT, Joyce MG, Louder MK, Tumba N, Yang Y, Zhang B, Cohen MS, Haynes BF, Mascola JR, Morris L, Munro JB, Blanchard SC, Mothes W, Connors M, Kwong PD. Structure and immune recognition of trimeric pre-fusion HIV-1 Env. Nature. 2014 Oct 23;514(7523):455-61.
McLellan JS, Chen M, Joyce MG, Sastry M, Stewart-Jones GB, Yang Y, Zhang B, Chen L, Srivatsan S, Zheng A, Zhou T, Graepel KW, Kumar A, Moin S, Boyington JC, Chuang GY, Soto C, Baxa U, Bakker AQ, Spits H, Beaumont T, Zheng Z, Xia N, Ko SY, Todd JP, Rao S, Graham BS, Kwong PD. Structure-based design of a fusion glycoprotein vaccine for respiratory syncytial virus. Science. 2013 Nov 1;342(6158):592-8.
Zhou T, Georgiev I, Wu X, Yang ZY, Dai K, Finzi A, Kwon YD, Scheid JF, Shi W, Xu L, Yang Y, Zhu J, Nussenzweig MC, Sodroski J, Shapiro L, Nabel GJ, Mascola JR, Kwong PD. Structural basis for broad and potent neutralization of HIV-1 by antibody VRC01. Science. 2010 Aug 13;329(5993):811-7.
Zhou T, Xu L, Dey B, Hessell AJ, Van Ryk D, Xiang SH, Yang X, Zhang MY, Zwick MB, Arthos J, Burton DR, Dimitrov DS, Sodroski J, Wyatt R, Nabel GJ, Kwong PD. Structural definition of a conserved neutralization epitope on HIV-1 gp120. Nature. 2007 Feb 15;445(7129):732-7.
Kwong PD, Wyatt R, Robinson J, Sweet RW, Sodroski J, Hendrickson WA. Structure of an HIV gp120 envelope glycoprotein in complex with the CD4 receptor and a neutralizing human antibody. Nature. 1998 Jun 18;393(6686):648-59.
Visit PubMed for a complete publication listing.
Trimeric gp120 models have been superseded by the atomic-level crystal structure of trimeric HIV-1 Env 4TVP.
Trimeric 4TVP without antibodies (PDB)
Docked gp120 : CD4 : CCR5Nt (PDB)
Visit the RCSB PDB for a more complete listing of SBS structures.
For more information on research conducted by Dr. Kwong, visit the Structural Bioinformatics Core Section.
Last Updated August 24, 2015