Dichotomy in Neutralizing Antibody Induction to Peptide-Conjugated Vaccine in Squalene Emulsion Contrast With Aluminum Hydroxide Formulation

Abstract

W614A-3S peptide is a modified 3S motif of the HIV-gp41 (mutation W614A). We previously detected the presence of natural neutralizing antibodies directed against W614A-3S peptide (NAbs) in long-term non-progressor HIV+ patients. Here, we compared the efficacy of W614A-3S peptide formulated in either squalene emulsion (SQE) or in aluminum hydroxide (Alum) in inducing broadly-NAbs (bNAbs). Rabbit and mouse models were used to screen the induction of bNAbs following 4 immunizations. SQE was more efficient than Alum formulation in inducing W614A-3S-specific bNAbs with up to 67%–93% of HIV strains neutralized. We then analyzed the quality of peptide-specific murine B cells by single-cell gene expression by quantitative reverse transcription-PCR and single-cell V(D)J sequencing. We found more frequent germinal center B cells in SQE than in Alum, albeit with a different gene expression profile. The V(D)J sequencing of W614A-3S-specific BCR showed significant differences in BCR sequences and validates the dichotomy between adjuvant formulations. All sixteen BCR sequences which were cloned were specific of peptide. Adjuvant formulations of W614A-3S-peptide-conjugated immunogen impact the quantity and quality of B cell immune responses at both the gene expression level and BCR sequence.

Comprehending B-Cell Epitope Prediction to Develop Vaccines and Immunodiagnostics

“…Nevertheless, BCEP can support the development of vaccines and immunodiagnostics provided that its limitations are adequately comprehended and addressed. be produced from peptides comprising disordered BCEs of selected target proteins (e.g., pathogen virulence factors), to elicit production of antipeptide antibodies (i.e., peptide antibodies (22)) that can neutralize the biological activity of the proteins (4,(23)(24)(25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35)(36). Such an approach is viable where the BCEs are disordered in both the peptides and the proteins; but if the BCEs are conformationally constrained (e.g., folded) in the proteins, their binding by the antipeptide antibodies may fail to occur, as is thought to be the case among unsuccessful attempts at peptide-based vaccine development (16).…”