H5N1 Vaccine–Elicited Memory B Cells Are Genetically Constrained by the IGHV Locus in the Recognition of a Neutralizing Epitope in the Hemagglutinin Stem

Abstract

Due to significant viral diversity, vaccines that elicit durable and broad protection against influenza have been elusive. Recent research has focused on the potential of highly conserved regions of the viral hemagglutinin (HA) as targets for broadly neutralizing antibody responses. Antibodies that bind the highly conserved stem or stalk of HA can be elicited by vaccination in humans and animal models and neutralize diverse influenza strains. However, the frequency and phenotype of HA stem-specific B cells in vivo remains unclear. Here we characterize HA stem-specific B cell responses following H5N1 vaccination and describe the re-expansion of a pre-existing population of memory B cells specific for stem epitopes. This population utilizes primarily, but not exclusively, IGHV1-69-based immunoglobulins for HA recognition. However within some subjects, allelic polymorphism at the ighv1-69 locus can limit IGHV1-69 immunodominance and may reduce circulating frequencies of stem-reactive B cells in vivo. The accurate definition of allelic selection, recombination requirements and ontogeny of neutralizing antibody responses to influenza will aid rational influenza vaccine design.

Vaccine-Induced Antibodies that Neutralize Group 1 and Group 2 Influenza A Viruses

“…We used recombinant group 1-specific (H5) and group 2-specific (H3) HA probes – modified to prevent sialic acid binding (HAΔSA) (Wheatley et al, 2015; Whittle et al, 2014) – to co-stain and sort PBMCs isolated two weeks post H5N1 MIV boost (Figure 1C and S2). We recovered sequences of memory B cell immunoglobulin gene transcripts from six of the ten studied subjects (Figure 1D).…”

“…In terms of reproducibility, the HV1-69-derived antibodies have the additional advantage of utilizing heavy chain-only recognition, and prior studies have shown their vaccine-induced elicitation (Khurana et al, 2013; Ledgerwood et al, 2011; Ledgerwood et al, 2013; Sui et al, 2009; Wheatley et al, 2015; Whittle et al, 2014). However, HV1-69-derived antibodies generally do not neutralize both group 1 and 2 strains of influenza A, and, only a single HV1-69-derived antibody has been identified (CR9114) capable of neutralizing both group 1 and 2 strains of influenza A (Dreyfus et al, 2012).…”

“…We previously showed that subjects enrolled in the phase I clinical trial, VRC 310 – who received an A/Indonesia/05/2005 monovalent inactivated virus (MIV) vaccine primed by an H5 DNA plasmid vaccine (Ledgerwood et al, 2011; Ledgerwood et al, 2013) (Table S1A) – showed transient expansion of H1- and H5-cross reactive memory B cells specific to the HA stem (Wheatley et al, 2015; Whittle et al, 2014). To determine whether these memory B cells might encode multidonor class antibodies capable of neutralizing group 1 and 2 influenza A virus, we sorted memory B cells that reacted with both H5 (group 1) and H3 (group 2) HAs.…”

Antibody Responses with Fc-Mediated Functions after Vaccination of HIV-Infected Subjects with Trivalent Influenza Vaccine

“…The role of vaccination in boosting preexisting versus generating new nonNAb responses remains to be clarified. Technologies to define influenza-specific B cells and sequence their Ig genes allow a more detailed probe of preexisting versus new influenza-specific Ab responses and could be applied to non-NAb responses (42).…”

Implications of broadly neutralizing antibodies in the development of a universal influenza vaccine

“…Interestingly, binding of antibodies with this re-arrangement to the stem domain has been shown to be mediated primarily by the heavy chain with little contribution of the light chain [28]. Additionally, while many antibodies are still able to retain their binding when reverted to the V H 1-69 germline sequence, the presence of multiple V H 1-69 polymorphisms that do not bind suggests that there may be a genetic bias in the ability to mount broadly neutralizing antibody responses, with certain alleles of V H 1-69 being more favorable in producing these antibodies [30,31*]. However, human-derived broadly neutralizing antibodies that do not use the V H 1-69 gene have also been characterized, signifying that cross-reactivity is not exclusively linked to the V H 1-69 allele [22].…”