Browsing by Subject "GERMINAL-CENTERS"

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    Functional Relevance of Improbable Antibody Mutations for HIV Broadly Neutralizing Antibody Development.
    (Cell host & microbe, 2018-06) Wiehe, Kevin; Bradley, Todd; Meyerhoff, R Ryan; Hart, Connor; Williams, Wilton B; Easterhoff, David; Faison, William J; Kepler, Thomas B; Saunders, Kevin O; Alam, S Munir; Bonsignori, Mattia; Haynes, Barton F
    HIV-1 broadly neutralizing antibodies (bnAbs) require high levels of activation-induced cytidine deaminase (AID)-catalyzed somatic mutations for optimal neutralization potency. Probable mutations occur at sites of frequent AID activity, while improbable mutations occur where AID activity is infrequent. One bottleneck for induction of bnAbs is the evolution of viral envelopes (Envs) that can select bnAb B cell receptors (BCR) with improbable mutations. Here we define the probability of bnAb mutations and demonstrate the functional significance of key improbable mutations in three bnAb B cell lineages. We show that bnAbs are enriched for improbable mutations, which implies that their elicitation will be critical for successful vaccine induction of potent bnAb B cell lineages. We discuss a mutation-guided vaccine strategy for identification of Envs that can select B cells with BCRs that have key improbable mutations required for bnAb development.
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    ItemOpen Access
    Initiation of HIV neutralizing B cell lineages with sequential envelope immunizations.
    (Nature communications, 2017-11-23) Williams, Wilton B; Zhang, Jinsong; Jiang, Chuancang; Nicely, Nathan I; Fera, Daniela; Luo, Kan; Moody, M Anthony; Liao, Hua-Xin; Alam, S Munir; Kepler, Thomas B; Ramesh, Akshaya; Wiehe, Kevin; Holland, James A; Bradley, Todd; Vandergrift, Nathan; Saunders, Kevin O; Parks, Robert; Foulger, Andrew; Xia, Shi-Mao; Bonsignori, Mattia; Montefiori, David C; Louder, Mark; Eaton, Amanda; Santra, Sampa; Scearce, Richard; Sutherland, Laura; Newman, Amanda; Bouton-Verville, Hilary; Bowman, Cindy; Bomze, Howard; Gao, Feng; Marshall, Dawn J; Whitesides, John F; Nie, Xiaoyan; Kelsoe, Garnett; Reed, Steven G; Fox, Christopher B; Clary, Kim; Koutsoukos, Marguerite; Franco, David; Mascola, John R; Harrison, Stephen C; Haynes, Barton F; Verkoczy, Laurent
    A strategy for HIV-1 vaccine development is to define envelope (Env) evolution of broadly neutralizing antibodies (bnAbs) in infection and to recreate those events by vaccination. Here, we report host tolerance mechanisms that limit the development of CD4-binding site (CD4bs), HCDR3-binder bnAbs via sequential HIV-1 Env vaccination. Vaccine-induced macaque CD4bs antibodies neutralize 7% of HIV-1 strains, recognize open Env trimers, and accumulate relatively modest somatic mutations. In naive CD4bs, unmutated common ancestor knock-in mice Env+B cell clones develop anergy and partial deletion at the transitional to mature B cell stage, but become Env- upon receptor editing. In comparison with repetitive Env immunizations, sequential Env administration rescue anergic Env+ (non-edited) precursor B cells. Thus, stepwise immunization initiates CD4bs-bnAb responses, but immune tolerance mechanisms restrict their development, suggesting that sequential immunogen-based vaccine regimens will likely need to incorporate strategies to expand bnAb precursor pools.