Our overall research goal is to understand the ability of the HIV-1 envelope (Env) to elicit a broad and potent neutralizing antibody response. The HIV-1 Env-specific binding antibodies are readily elicited in natural infection and through immunizations; however, most of the Env-binding antibodies cannot neutralize the virus. Hence, understanding how a subset of the Env-binding antibodies acquires the neutralization function is critical for antibody-based vaccine development.
Research project 1: To determine the key changes in transition from narrow autologous to broad heterologous antibody neutralization during HIV-1 infection
The HIV-1 Env has been considered poor in its ability to elicit broad and potent neutralizing antibodies. Only a small fraction of HIV-1 infected individuals mount broad and potent neutralizing antibody responses, and such responses typically do not appear until two years after infection. However, almost all HIV-1 infected individuals make neutralizing antibodies against their own initial infecting viral strains (autologous strains). Currently we do not understand how the early narrow autologous neutralizing antibodies in some individuals later become broad and capable of neutralizing strains from other individuals (heterologous strains). The interpretation of current data is that the early narrow autologous neutralizing antibodies are directed to highly variable regions such as the V1V2, while the later broadly neutralizing antibodies arise by targeting relatively conserved regions such as the CD4-binding site (CD4bs). To date, there is no evidence of the V1V2-specific antibodies changing their specificity to the CD4bs during the course of infection; therefore, these antibody epitopes are likely to be separated and not a continuous process that could be explained by antibody affinity maturation within individual antibody clones.
To facilitate our understanding about how antibody specificities diversify and how broadly neutralizing antibodies arise in vivo, we propose to follow the antibody response longitudinally to determine the key changes in transitioning from neutralizing only narrow autologous strains to broad heterologous strains. We hypothesize that broadly neutralizing antibodies arise through two mechanisms: 1) through founder B cells that precisely target a conserved neutralizing epitope; in this case, once the antibody obtains sufficient somatic hypermutation to neutralize autologous viral strains, it simultaneously acquires neutralization breadth against heterologous strains; 2) through founder B cells that target suboptimal epitopes with narrow autologous neutralizing activity that shift later (by additional somatic mutations) to optimal epitopes in response to autologous viral escape to acquire neutralization breadth.
Research project 2: To determine the maturation pathways of antibody clonal lineages by characterizing the naïve B cell reactivity with HIV-1 Env and by 454 deep sequencing of the human antibodyome
Broadly neutralizing antibodies are products of HIV-1 Env-stimulated naïve founder B cells that go through activation, clonal expansion, and somatic hypermutation. Vaccine candidates that can trigger the "ancestral states" of B cells that give rise to neutralizing antibodies may be promising. To evaluate such vaccine candidates, identification and characterization of the ancestral states of antibodies become essential. To begin defining the ancestral states of neutralizing antibodies, we propose to study the reactivity of naïve B cell pool with the HIV-1 Env, and apply 454 deep sequencing technologies to maximize coverage of the diverse human antibody repertoire. We will test the hypothesis that the HIV-1 Env-reactive B cells that give rise to broadly neutralizing antibodies could be identified in the naïve B cell pool. Results of the fully characterized neutralizing antibody lineages will provide valuable information about the antibody maturation pathways, and allow recapitulation of the antibody response through immunization.
Research project 3: To isolate and characterize broadly neutralizing antibodies from HIV-1 infected pediatric donors
Currently known broadly neutralizing antibodies were all isolated from adults, and a common feature of these antibodies is high levels of somatic hypermutation. Current data suggest that compared to adults, antibody somatic mutation levels in response to infections are relatively low in children. However, HIV-1 vertically infected children could develop high titers of neutralizing antibodies in serum against autologous viruses. Therefore, we are interested in determining if neutralizing antibodies in children are broad, and if so, how these antibodies achieve breadth and potency. We will test the hypothesis that some HIV-1 broadly neutralizing antibodies only require moderate levels of somatic hypermutation; alternatively, whereas children generally have low antibody somatic mutations in response to infections, this may not be the case with HIV-1 infection, and the HIV-1 broadly neutralizing antibodies in children may exhibit similarly high levels of somatic hypermutation as adults do. To test this hypothesis, we propose to isolate and study monoclonal antibodies from the HIV-1 infected pediatric donors.
- Wu, X., C. Wang, S. O'Dell, Y. Li, B. Keele, Z. Yang, H. Imamichi, N. Doria-Rose, J. Hoxie, M. Connors, G. Shaw, R. Wyatt and J. Mascola. Selection pressure on HIV-1 envelope by broadly neutralizing antibodies to the conserved CD4-binding site. Journal of Virology 2012, 86: 5844-5856 [view]
- Wu, X.*, T. Zhou*, J. Zhu*, B. Zhang, I. Georgiev, C. Wang, X. Chen, N. Longo, M. Louder, K. McKee, S. O'Dell, S. Perfetto, S. Schmidt, W. Shi, L. Wu, Y. Yang, Z. Yang, Z. Yang, Z. Zhang, M. Bonsignori, J. Crump, S. Kapiga, N. Sam, B. Haynes, M. Simek, D. Burton, W. Koff, N. Doria-Rose, M. Connors, NISC Comparative Sequencing Program, J. Mullikin, G. Nabel, M. Roederer, L. Shapiro, P. Kwong* and J. Mascola*. Focused evolution of HIV-1 neutralizing antibodies revealed by structures and deep sequencing. Science 2011, 333: 1593-1602 Cover feature *equal contribution [view]
- Wu, X., A. Changela, S. O'Dell, S. Schmidt, M. Pancera, Y. Yang, B. Zhang, M. Gorny, S. Phogat, J. Robinson, L. Stamatatos, S. Zolla-Pazner, P. Kwong and J. Mascola. Immunotypes of a quaternary site of HIV-1 vulnerability and their recognition by antibodies. Journal of Virology 2011, 85: 4578-4585 [view]
- Wu, X.*, Z. Yang*, Y. Li*, C. Hogerkorp, W. Schief, M. Seaman, T. Zhou, S. Schmidt, L. Wu, L. Xu, S. O'Dell, K. McKee, N. Longo, M. Louder, D. Wycuff, Y. Feng, J. Guenaga, N. Doria-Rose, M. Connors, P. Kwong, M. Roederer, R. Wyatt, G. Nabel* and J. Mascola*. Rational design of envelope identifies broadly neutralizing human monoclonal antibodies to HIV-1. Science 2010, 329: 856-861 *equal contribution [view]
- Zhou, T., I. Georgiev*, Wu, X.*, Z. Yang*, K. Dai, A. Finzi, Y. Kwon, J. Scheid, W. Shi, L. Xu, Y. Yang, J. Zhu, M. Nussenzweig, J. Sodroski, L. Shapiro, G. Nabel, J. Mascola and P. Kwong. Structural basis for broad and potent neutralization of HIV-1 by antibody VRC01. Science 2010, 329: 811-817 *equal contribution [view]
- Chen, L.*, Kwon, Y.*, Zhou, T.*, Wu, X., S. O'Dell, L. Cavacini, A. Hessell, M. Pancera, M. Tang, L. Xu, Z. Yang, M. Zhang, J. Arthos, D. Burton, D. Dimitrov, G. Nabel, M. Posner, J. Sodroski, R. Wyatt, J. Mascola and P. Kwong. Structural basis of immune evasion at the site of CD4 attachment on HIV-1 gp120. Science 2009, 326: 1123-1127 *equal contribution [view]
- Wu, X.*, T. Zhou*, S. O'Dell, R. Wyatt, P. Kwong and J. Mascola. Mechanism of HIV-1 resistance to monoclonal antibody b12 that effectively targets the site of CD4 attachment. Journal of Virology 2009, 83: 10892-10907 Spotlight paper *equal contribution [view]
- Wu, X., A. Parast, B. Richardson, R. Nduati, G. John-Stewart, D. Mbori-Ngacha, S. Rainwater and J. Overbaugh. Neutralization escape variants of HIV-1 are transmitted from mother to infant. Journal of Virology 2006, 80: 835-844 Spotlight paper [view]
- Sagar, M., Wu, X., S. Lee and J. Overbaugh. Human immunodeficiency virus type 1 V1-V2 envelope loop sequences expand and add glycosylation sites over the course of infection, and these modifications affect antibody neutralization sensitivity. Journal of Virology 2006, 80: 9586-9598 [view]
- Wu, X., S. Hall and S. Jackson. Tropism-restricted neutralization by secretory IgA from parotid saliva of HIV-1-infected individuals. AIDS Research and Human Retroviruses 2003, 19: 275-281 [view]