Biology subjects

Koo, J.-H.

Publications and source records attributed to Koo, J.-H..

4 recordsLinked to original sources

bioRxiv2025

A Single Structure-Derived Computational Metric Predicts High-Affinity Antibody Selection Against a Malaria Antigen

There is an increasing need for improved malaria antibodies that can be used in passive immunization strategies to reduce the burden of malaria in endemic regions. Despite considerable progress, the identification or development of variants that meet stringent performance requirements remains a challenge. A key strategy has been the improvement of prototypic antibodies targeting the repeat antigens on Plasmodium falciparum circumsporozoite protein (PfCSP). In this work, we derive a computational metric from predicted protein structures that efficiently captures affinity information of antibody variants of the PfCSP-targeting antibody, CIS43. We then use this metric to rapidly explore sequence space as large as >3x10^47 variants using principles of the germinal center, deriving new high-affinity CIS43 variants from the method. We further extend this framework to generate high-affinity variants of an unrelated PfCSP-targeting antibody, L9, by maturing both homotypic and antigen-binding interactions, which demonstrates substantial flexibility of the approach. Taken together, we show that coupling micro-evolutionarily selected mutations to in silico screening permits the selection of high-affinity malaria antibodies.

immunology↗

bioRxiv2025

Protective immunity against malaria by a nanoparticle CIS43-based junctional vaccine alone or in combination with R21

Repetitive display of the major repeats of the Plasmodium falciparum circumsporozoite protein (PfCSP) is the basis for two WHO-recommended vaccines: RTS,S/AS01 and R21/Matrix-M. Recently, however, the CIS43 monoclonal antibody that preferentially targets the junctional region of PfCSP has been shown to be highly protective in humans, highlighting its junctional epitope as a key vaccine target. Here, we develop a vaccine based on the tandem repeats of the junctional epitope displayed on a self-assembling nanoparticle, and compare this CIS43-based junctional vaccine alone or in combination with the benchmark R21 vaccine, using both B cell analysis and monoclonal antibody isolation to define targeting of the immune response. Comparable reduction in liver burden was observed following vaccination with junctional and R21 vaccines at a dose of 1 g. At a dose of 0.25 g, a modest reduction of malaria-liver burden with the junctional vaccine was observed compared to R21. Further, combining junctional and R21 vaccines induced modestly enhanced protection compared to either vaccine alone. While the R21 vaccine elicited antibodies primarily against the major repeats, the junctional vaccine elicited antibodies against both junctional and major repeat regions. In vivo-B cell analysis and isolation of monoclonal antibodies confirmed differences in vaccine-induced antibody specificities. Altogether, these data suggest the nanoparticle-formatted tandem-repeated CIS43-junctional vaccine to be a promising approach to broaden immunity against malaria, either as a standalone intervention or in combination with R21. HIGHLIGHTSO_LIDeveloped a self-assembling nanoparticle-displayed junctional vaccine of PfCSP based on tandem repeats of the epitope preferentially targeted by the highly protective CIS43 antibody C_LIO_LIThe CIS43-based junctional vaccine at low doses significantly reduced liver burden following malaria challenge in mice C_LIO_LIFollowing either low or high doses of the junctional vaccine in naive mice, adoptively transferred B cells expressing the CIS43 inferred germline sequence yielded a high frequency of germinal center and ASC responses C_LIO_LIThe CIS43-based junctional vaccine elicits antibodies against junctional and major repeat regions whereas the R21 vaccine elicits responses primarily against the major repeat region C_LIO_LIAt low dose, the CIS43-based junctional vaccine given together with the R21 vaccine showed modestly improved control of liver burden compared to either vaccine alone C_LI

immunology↗

bioRxiv2022

Humanized V(D)J-rearranging and TdT-expressing Mouse Vaccine Models with Physiological HIV-1 Broadly Neutralizing Antibody Precursors

Antibody heavy chain (HC) and light chain (LC) variable region exons are assembled by V(D)J recombination. V(D)J junctional regions encode complementarity-determining-region 3 (CDR3), an antigen-contact region immensely diversified through non-templated nucleotide additions ("N-regions") by terminal deoxynucleotidyl transferase (TdT). HIV-1 vaccine strategies seek to elicit human HIV-1 broadly neutralizing antibodies (bnAbs), such as the potent CD4-binding site VRC01-class bnAbs. Mice with primary B cells that express receptors (BCRs) representing bnAb precursors are used as vaccination models. VRC01-class bnAbs uniformly use human HC VH1-2 and commonly use human LCs V{kappa}3-20 or V{kappa}1-33 associated with an exceptionally short 5-amino-acid (5-aa) CDR3. Prior VRC01-class models had non-physiological precursor levels and/or limited precursor diversity. Here, we describe VRC01-class rearranging mice that generate more physiological primary VRC01-class BCR repertoires via rearrangement of VH1-2, as well as V{kappa}1-33 and/or V{kappa}3-20 in association with diverse CDR3s. Human-like TdT expression in mouse precursor B cells increased LC CDR3 length and diversity and also promoted generation of shorter LC CDR3s via N-region suppression of dominant microhomology-mediated V{kappa}-to-J{kappa} joins. Priming immunization with eOD-GT8 60mer, which strongly engages VRC01 precursors, induced robust VRC01-class germinal center (GC) B cell responses. V{kappa}3-20-based responses were enhanced by N-region addition, which generates V{kappa}3-20-to-J{kappa} junctional sequence combinations that encode VRC01-class 5-aa CDR3s with a critical E residue. VRC01-class-rearranging models should facilitate further evaluation of VRC01-class prime and boost immunogens. These new VRC01-class mouse models establish a prototype for generation of vaccine-testing mouse models for other HIV-1 bnAb lineages that employ different HC or LC Vs. Significance StatementMouse models that express human precursors of HIV-1 broadly neutralizing antibodies (bnAbs) are useful for evaluating vaccination strategies for eliciting such bnAbs in humans. Prior models were handicapped by non-physiological frequency and/or diversity of B lymphocytes that express the bnAb precursors. We describe a new class of mouse models in which the mice express humanized bnAb precursors at a more physiologically relevant level through developmental rearrangement of both antibody heavy and light chain gene segments that encode the precursors. The model also incorporated a human enzyme that diversifies the rearranging gene segments and promotes generation of certain variable region sequences needed for the response. This new class of mouse models should facilitate preclinical evaluation of candidate human HIV-1 vaccination strategies.

immunology↗

bioRxiv2022

Bystander memory-phenotype conventional CD4+ T cells exacerbating autoimmune neuroinflammation

Memory-phenotype (MP) CD4+ T cells are a substantial population of conventional T cells that exist in steady-state mice, and their immunologic functions in autoimmune disease have not yet been studied. In this work, we unveil a unique phenotype of MP CD4+ T cells by analyzing single-cell transcriptomics and T cell receptor (TCR) repertoires. We found that steady-state MP CD4+ T cells exist regardless of germ and food-antigen which are composed of heterogenous effector subpopulations. Distinct subpopulations of MP CD4+ T cells are specifically activated by IL-1 family cytokines and STAT activators, revealing that the cells have TCR-independent effector functions. Especially, CCR6high MP CD4+ T cells are major responders to IL-1{beta} and IL-23 without MOG35-55 antigen reactivity, which gives them pathogenic-Th17 characteristics and allows them to contribute to autoimmune encephalomyelitis. We identified Bhlhe40 in CCR6high MP CD4+ T cells drives the expression of GM-CSF, contributing to CNS pathology in experimental autoimmune encephalomyelitis. Collectively, our findings reveal heterogeneity of MP CD4+ T cells that can contribute to autoimmune neuroinflammation in bystander manner synergistically with antigen-specific T cells.

immunology↗