scholarly journals Long-lasting germinal center responses to a priming immunization with continuous proliferation and somatic mutation

2021 ◽  
Author(s):  
Jeong Hyun Lee ◽  
Henry J. Sutton ◽  
Christopher A. Cottrell ◽  
Ivy Phung ◽  
Gabriel Ozorowski ◽  
...  
Keyword(s):  
B Cells ◽  
Neutralizing Antibodies ◽  
Somatic Hypermutation ◽  
Transcriptional Profiling ◽  
Cell Lineage ◽  
Booster Immunization ◽  
Selection For ◽  
Env Protein ◽  
Additional Antigen ◽  
Immunodominant Epitopes

Germinal centers (GCs) are the engines of antibody evolution. Using HIV Env protein immunogen priming in rhesus monkeys (RM) followed by a long period without further immunization, we demonstrate GC B cells (BGC) lasted at least 6 months (29 weeks), all the while maintaining rapid proliferation. A 186-fold BGC cell increase was present by week 10 compared to a conventional immunization. Single cell transcriptional profiling revealed that both light zone and dark zone GC states were sustained throughout the 6 months. Antibody somatic hypermutation (SHM) of BGC cells continued to accumulate throughout the 29 week priming period, with evidence of selective pressure. Additionally, Env-binding BGC cells were still 49-fold above baseline 29 weeks after immunization, suggesting that they could be active for significantly longer periods of time. High titers of HIV neutralizing antibodies were generated after a single booster immunization. Fully glycosylated HIV trimer protein is a complex antigen, posing significant immunodominance challenges for B cells, among other difficulties. Memory B cells (BMem) generated under these long priming conditions had higher levels of SHM, and both BMem cells and antibodies were more likely to recognize non-immunodominant epitopes. Numerous BGC cell lineage phylogenies spanning the >6-month GC period were identified, demonstrating continuous GC activity and selection for at least 191 days, with no additional antigen exposure. A long prime, adjuvanted, slow delivery (12-day) immunization approach holds promise for difficult vaccine targets, and suggests that patience can have great value for tuning GCs to maximize antibody responses.

scholarly journals B cells expressing authentic naive human VRC01-class BCRs can be primed and recruited to germinal centers in multiple independent mouse models

2020 ◽  
Author(s):  
Deli Huang ◽  
Robert K. Abbott ◽  
Colin Havenar-Daughton ◽  
Patrick D. Skog ◽  
Rita Al-Kolla ◽  
...  
Keyword(s):  
B Cells ◽  
B Cell ◽  
Neutralizing Antibodies ◽  
Vaccine Development ◽  
Somatic Hypermutation ◽  
Germinal Centers ◽  
Healthy Human ◽  
Central Tenet ◽  
Class B ◽  
Precursor Frequency

ABSTRACTAnimal models of human antigen-specific B cell receptors (BCR) generally depend on “inferred germline” sequences, and thus their relationship to authentic naive human B cell BCR sequences and affinities is unclear. Here, BCR sequences from authentic naive human VRC01-class B cells from healthy human donors were selected for the generation of three new BCR knock-in mice. The BCRs span the physiological range of affinities found in humans, and use three different light chains (VK3-20, VK1-5, and VK1-33) found among subclasses of naive human VRC01-class B cells and HIV broadly neutralizing antibodies (bnAbs). The germline-targeting HIV immunogen eOD-GT8 60mer is currently in clinical trial as a candidate bnAb vaccine priming immunogen. To attempt to model human immune responses to the eOD-GT8 60mer, we tested each authentic naive human VRC01-class BCR mouse model under rare human physiological B cell precursor frequency conditions. B cells with high (HuGL18HL) or medium (HuGL17HL) affinity BCRs were primed, recruited to germinal centers, accrued substantial somatic hypermutation, and formed memory B cells. Precursor frequency and affinity interdependently influenced responses. Taken together, these experiments utilizing authentic naive human VRC01-class BCRs validate a central tenet of germline-targeting vaccine design and extend the overall concept of the reverse vaccinology approach to vaccine development.

scholarly journals Sequence intrinsic somatic mutation mechanisms contribute to affinity maturation of VRC01-class HIV-1 broadly neutralizing antibodies

2017 ◽  
Vol 114 (32) ◽  
pp. 8614-8619 ◽  
Author(s):  
Joyce K. Hwang ◽  
Chong Wang ◽  
Zhou Du ◽  
Robin M. Meyers ◽  
Thomas B. Kepler ◽  
...  
Keyword(s):  
B Cells ◽  
Neutralizing Antibodies ◽  
Somatic Hypermutation ◽  
Human Subjects ◽  
Variable Region ◽  
Affinity Maturation ◽  
Broadly Neutralizing Antibodies ◽  
Variable Regions ◽  
Complementarity Determining Regions ◽  
Hiv 1

Variable regions of Ig chains provide the antigen recognition portion of B-cell receptors and derivative antibodies. Ig heavy-chain variable region exons are assembled developmentally from V, D, J gene segments. Each variable region contains three antigen-contacting complementarity-determining regions (CDRs), with CDR1 and CDR2 encoded by the V segment and CDR3 encoded by the V(D)J junction region. Antigen-stimulated germinal center (GC) B cells undergo somatic hypermutation (SHM) of V(D)J exons followed by selection for SHMs that increase antigen-binding affinity. Some HIV-1–infected human subjects develop broadly neutralizing antibodies (bnAbs), such as the potent VRC01-class bnAbs, that neutralize diverse HIV-1 strains. Mature VRC01-class bnAbs, including VRC-PG04, accumulate very high SHM levels, a property that hinders development of vaccine strategies to elicit them. Because many VRC01-class bnAb SHMs are not required for broad neutralization, high overall SHM may be required to achieve certain functional SHMs. To elucidate such requirements, we used a V(D)J passenger allele system to assay, in mouse GC B cells, sequence-intrinsic SHM-targeting rates of nucleotides across substrates representing maturation stages of human VRC-PG04. We identify rate-limiting SHM positions for VRC-PG04 maturation, as well as SHM hotspots and intrinsically frequent deletions associated with SHM. We find that mature VRC-PG04 has low SHM capability due to hotspot saturation but also demonstrate that generation of new SHM hotspots and saturation of existing hotspot regions (e.g., CDR3) does not majorly influence intrinsic SHM in unmutated portions of VRC-PG04 progenitor sequences. We discuss implications of our findings for bnAb affinity maturation mechanisms.

scholarly journals The germinal center antibody response in health and disease

F1000Research ◽  
2016 ◽  
Vol 5 ◽  
pp. 999 ◽  
Author(s):  
Anthony L. DeFranco
Keyword(s):  
B Cells ◽  
Antibody Response ◽  
Germinal Center ◽  
Neutralizing Antibodies ◽  
Plasma Cells ◽  
Somatic Hypermutation ◽  
Effective Control ◽  
Immune Recognition ◽  
Immunoglobulin Gene ◽  
Variable Regions

The germinal center response is the delayed but sustained phase of the antibody response that is responsible for producing high-affinity antibodies of the IgG, IgA and/or IgE isotypes. B cells in the germinal center undergo re-iterative cycles of somatic hypermutation of immunoglobulin gene variable regions, clonal expansion, and Darwinian selection for cells expressing higher-affinity antibody variants. Alternatively, selected B cells can terminally differentiate into long-lived plasma cells or into a broad diversity of mutated memory B cells; the former secrete the improved antibodies to fight an infection and to provide continuing protection from re-infection, whereas the latter may jumpstart immune responses to subsequent infections with related but distinct infecting agents. Our understanding of the molecules involved in the germinal center reaction has been informed by studies of human immunodeficiency patients with selective defects in the production of antibodies. Recent studies have begun to reveal how innate immune recognition via Toll-like receptors can enhance the magnitude and selective properties of the germinal center, leading to more effective control of infection by a subset of viruses. Just as early insights into the nature of the germinal center found application in the development of the highly successful conjugate vaccines, more recent insights may find application in the current efforts to develop new generations of vaccines, including vaccines that can induce broadly protective neutralizing antibodies against influenza virus or HIV-1.

scholarly journals Vaccine Elicitation of HIV Broadly Neutralizing Antibodies from Engineered B cells

2020 ◽  
Author(s):  
Deli Huang ◽  
Jenny Tuyet Tran ◽  
Alex Olson ◽  
Thomas Vollbrecht ◽  
Mariia V. Guryleva ◽  
...  
Keyword(s):  
B Cells ◽  
B Cell ◽  
Neutralizing Antibodies ◽  
Plasma Cells ◽  
Somatic Hypermutation ◽  
Wild Type ◽  
Broadly Neutralizing Antibodies ◽  
Low Frequencies ◽  
Primary Mouse ◽  
Functional Receptor

HIV broadly neutralizing antibodies (bnAbs) can suppress viremia and protect against infection1. However, their elicitation is made difficult by low frequencies of appropriate precursor B cell receptors and the complex maturation pathways required to generate bnAbs from these precursors2. Antibody genes can be engineered into B cells for expression as both a functional receptor on cell surfaces and as secreted antibody3–5. Here, we show that HIV bnAb-engineered primary mouse B cells can be adoptively transferred and vaccinated in immunocompetent wild-type animals resulting in the expansion of durable bnAb memory and long-lived plasma cells. Somatic hypermutation after immunization indicated that engineered cells have the capacity to respond to an evolving pathogen. These results encourage further exploration of engineered B cell vaccines as a strategy for durable elicitation of HIV bnAbs to protect against infection and as a contributor to a functional cure.

scholarly journals Vaccine elicitation of HIV broadly neutralizing antibodies from engineered B cells

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Deli Huang ◽  
Jenny Tuyet Tran ◽  
Alex Olson ◽  
Thomas Vollbrecht ◽  
Mary Tenuta ◽  
...  
Keyword(s):  
B Cells ◽  
B Cell ◽  
Neutralizing Antibodies ◽  
Plasma Cells ◽  
Somatic Hypermutation ◽  
Hiv Cure ◽  
Broadly Neutralizing Antibodies ◽  
Low Frequencies ◽  
Primary Mouse ◽  
Immunocompetent Mice

AbstractHIV broadly neutralizing antibodies (bnAbs) can suppress viremia and protect against HIV infection. However, their elicitation is made difficult by low frequencies of appropriate precursor B cell receptors and the complex maturation pathways required to generate bnAbs from these precursors. Antibody genes can be engineered into B cells for expression as both a functional antigen receptor on cell surfaces and as secreted antibody. Here, we show that HIV bnAb-engineered primary mouse B cells can be adoptively transferred and vaccinated in immunocompetent mice resulting in the expansion of durable bnAb memory and long-lived plasma cells. Somatic hypermutation after immunization indicates that engineered cells have the capacity to respond to an evolving pathogen. These results encourage further exploration of engineered B cell vaccines as a strategy for durable elicitation of HIV bnAbs to protect against infection and as a contributor to a functional HIV cure.

scholarly journals Stereotypic neutralizing VH antibodies against SARS-CoV-2 spike protein receptor binding domain in COVID-19 patients and healthy individuals

2021 ◽  
pp. eabd6990
Author(s):  
Sang Il Kim ◽  
Jinsung Noh ◽  
Sujeong Kim ◽  
Younggeun Choi ◽  
Duck Kyun Yoo ◽  
...  
Keyword(s):  
B Cells ◽  
Receptor Binding ◽  
Neutralizing Antibodies ◽  
De Novo ◽  
Binding Domain ◽  
Host Cells ◽  
Spike Protein ◽  
Receptor Binding Domain ◽  
Healthy Individuals

Stereotypic antibody clonotypes exist in healthy individuals and may provide protective immunity against viral infections by neutralization. We observed that 13 out of 17 patients with COVID-19 had stereotypic variable heavy chain (VH) antibody clonotypes directed against the receptor-binding domain (RBD) of SARS-CoV-2 spike protein. These antibody clonotypes were comprised of immunoglobulin heavy variable (IGHV)3-53 or IGHV3-66 and immunoglobulin heavy joining (IGHJ)6 genes. These clonotypes included IgM, IgG3, IgG1, IgA1, IgG2, and IgA2 subtypes and had minimal somatic mutations, which suggested swift class switching after SARS-CoV-2 infection. The different immunoglobulin heavy variable chains were paired with diverse light chains resulting in binding to the RBD of SARS-CoV-2 spike protein. Human antibodies specific for the RBD can neutralize SARS-CoV-2 by inhibiting entry into host cells. We observed that one of these stereotypic neutralizing antibodies could inhibit viral replication in vitro using a clinical isolate of SARS-CoV-2. We also found that these VH clonotypes existed in six out of 10 healthy individuals, with IgM isotypes predominating. These findings suggest that stereotypic clonotypes can develop de novo from naïve B cells and not from memory B cells established from prior exposure to similar viruses. The expeditious and stereotypic expansion of these clonotypes may have occurred in patients infected with SARS-CoV-2 because they were already present.

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