Induction of broad multifunctional CD8+ and CD4+ T cells by hepatitis B virus antigen-based synthetic long peptides ex vivo

Abstract

IntroductionTherapeutic vaccination based on synthetic long peptides (SLP®) containing both CD4+ and CD8+ T cell epitopes is a promising treatment strategy for chronic hepatitis B infection (cHBV).MethodsWe designed SLPs for three HBV proteins, HBcAg and the non-secreted proteins polymerase and X, and investigated their ability to induce T cell responses ex vivo. A set of 17 SLPs was constructed based on viral protein conservation, functionality, predicted and validated binders for prevalent human leukocyte antigen (HLA) supertypes, validated HLA I epitopes, and chemical producibility.ResultsAll 17 SLPs were capable of inducing interferon gamma (IFNɣ) production in samples from four or more donors that had resolved an HBV infection in the past (resolver). Further analysis of the best performing SLPs demonstrated activation of both CD8+ and CD4+ multi-functional T cells in one or more resolver and patient sample(s). When investigating which SLP could activate HBV-specific T cells, the responses could be traced back to different peptides for each patient or resolver.DiscussionThis indicates that a large population of subjects with different HLA types can be covered by selecting a suitable mix of SLPs for therapeutic vaccine design. In conclusion, we designed a set of SLPs capable of inducing multifunctional CD8+ and CD4+ T cells ex vivo that create important components for a novel therapeutic vaccine to cure cHBV.

HLA class I peptidome analysis of synthetic long peptide-fed human dendritic cells for therapeutic vaccine design

“…This is exemplified by the identification of SLP-derived peptides HLYSHPIIL (Pol 502-510 ) and HLYSHPIILG (Pol 502-511 ). HLYSHPIIL but not HLYSHPIILG is a predicted HLA-A2:01-binder and demonstrated HLA-A2:01 epitope 8,63,64 . Both peptides are reproducibly found to be presented across all donors with high confidence (i.e.…”

“…Twelve HBV SLPs (Sup. Table 1) were gifted by ISA pharmaceuticals and designed and synthesized as described before 8 . Peripheral blood mononuclear cells (PBMCs) were isolated by Ficoll-Paque (Merck) density gradient centrifugation from blood of HLA-A*02:01+ HLA-A*11:01+ healthy donors collected from the local blood bank (Sanquin, The Netherlands).…”

“…One SLP may contain various HLA-I and class II (HLA-II) epitopes, creating a concentrated yet broad T cell priming potential 8,9 . Multiple SLPs can be combined to create a generic vaccine effective for each patient irrespective of their HLA type or viral genotype.…”

“…To find a cure for chronic hepatitis B virus infection (cHBV) that affects millions worldwide, we engaged in a study to design a HBV SLP-based therapeutic vaccine 8,30 . With this study we discovered components for a novel therapeutic vaccine.…”

“…Recently, the related SLP vaccine (ISA104) entered a phase I/II clinical safety and toxicity study (NCT05841095). In our studies we experienced that the design and testing of candidate SLPs and adjuvants relies heavily on in silico predictions and laborintensive in vitro T cell assays 8,26,30 . Moreover, these in vitro assays are skewed towards HLA-IImediated CD4+ T cell activation because of the scarcity of cross-presenting APCs in those cultures.…”