Abstract
The diversity of virus-specific antibodies and of B cells among different individuals is unknown. Using single-cell cloning of antibody genes, we generated recombinant human monoclonal antibodies from influenza nucleoprotein-specific memory B cells in four adult humans with and without preceding influenza vaccination. We examined the diversity of the antibody repertoires and found that NP-specific B cells used numerous immunoglobulin genes. The heavy chains (HCs) originated from 26 and the kappa light chains (LCs) from 19 different germ line genes. Matching HC and LC chains gave rise to 43 genetically distinct antibodies that bound influenza NP. The median lengths of the CDR3 of the HC, kappa and lambda LC were 14, 9 and 11 amino acids, respectively. We identified changes at 13.6% of the amino acid positions in the V gene of the antibody heavy chain, at 8.4 % in the kappa and at 10.6 % in the lambda V gene. We identified somatic insertions or deletions in 8.1% of the variable genes. We also found several small groups of clonal relatives that were highly diversified. Our findings demonstrate broadly diverse memory B cell repertoires for the influenza nucleoprotein. We found extensive variation within individuals with a high number of point mutations, insertions, and deletions, and extensive clonal diversification. Thus, structurally conserved proteins can elicit broadly diverse and highly mutated B-cell responses.
Highlights
The repertoire of antigen-specific B cells in humans remains largely unexplored due to difficulties in generating large sets of antibodies with defined specificity
The percentage of heavy chains (HCs)/light chains (LCs) pairs that gave rise to influenza virus NP-specific antibodies was negatively correlated with the percentage of isolated B cell samples from which gene sequence pairs could be amplified
Affinity maturation of B cells leads to variant progenies with point mutations in the variable regions of the HC and LC antibody genes
Summary
The repertoire of antigen-specific B cells in humans remains largely unexplored due to difficulties in generating large sets of antibodies with defined specificity. Two of the earliest studies using the BcR amplification technique generated influenza-specific antibodies from plasmablasts and HIV gp120-specific and gp41-specific antibodies from memory B cells [4, 5]. Single-cell antibody cloning has been used to generate and characterize antibodies against influenza virus [5,6,7], HIV [4, 8, 9], rotavirus [10], and Plasmodium falciparum [11]. Scheid et al obtained monoclonal antibodies by isolating memory B cells from individuals with chronic HIV infection [4]. Between 5 and 51 distinct B cell variants were identified within each individual, indicating that the BcR repertoires of the HIV glycoprotein-specific memory B cells are highly diverse. Our results indicate that the influenza NP-specific memory B cell response in humans is broad and diverse and is unique within each individual
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