Identification of broad binding class I HLA supertype epitopes to provide universal coverage of influenza A virus

Abstract

Influenza virus remains a significant health concern with current circulating strains that affect millions each year plus the threat of newly emerging strains, such as swine-origin H1N1 and avian H5N1. Our hypothesis is that influenza-derived HLA-Class I-restricted epitopes can be identified for use as a reagent to monitor and quantitate human CD8 + T cell responses and for vaccine development to induce protective cellular immunity. Protein sequences from influenza A virus strains currently in circulation, agents of past pandemics and zoonotic infections of man were evaluated for sequences predicted to bind to alleles representative of the most frequent HLA-A and -B (Class I) types worldwide. Peptides that bound several different HLA molecules and were conserved among diverse influenza subtypes were tested for their capacity to recall influenzaspecific immune responses using human donor PBMC. Accordingly, 28 different epitopes antigenic for human donor PBMC were identified and 25 were 100% conserved in the newly emerged swine-origin H1N1 strain. The epitope set defined herein should provide a reagent applicable to quantitate CD8 + T cell human responses irrespective of influenza subtype and HLA composition of the responding population. Additionally, these epitopes may be suitable for vaccine applications directed at the induction of cellular immunity.

The Immunodominant Influenza A Virus M158–66Cytotoxic T Lymphocyte Epitope Exhibits Degenerate Class I Major Histocompatibility Complex Restriction in Humans

“…In influenza A virus infection, the paradigm in immunodominant human CTL responses among IAV antigens concerns the HLA-A*02-restricted M1 58 -66 peptide (GILG FVFTL). CTLs specific for GILGFVFTL can be observed in almost all HLA-A*02-positive (A*02 ϩ ) donors who have been naturally exposed to influenza A virus (28,29). In a cohort of recruited individuals, we aimed to confirm adequate CTL responses against influenza A virus, and therefore, we first sought to characterize the GILGFVFTL-specific responses in these individuals.…”

“…The M1 58 -66 epitope is highly conserved among seasonal and pandemic influenza A virus strains, with 93% conservation reported for 69 strains tested (29). The immunogenicity of this peptide in the context of HLA-A*02-restricted CTL responses has been well characterized.…”

Murine polyomavirus VLPs as a platform for cytotoxic T cell epitope-based influenza vaccine candidates

“…To avoid aggregation, only the soluble domain of this protein was fused to VP2C, which came in two variations, VP2C-M1-I and VP2C-M1-II. The M1-I domain contains several epitopes (Figure 1.2) comprising several HLA supertypes such as A2, A3, B44, and B12 (Adar et al 2009;Alexander et al 2010;Assarsson et al 2008;Babon et al 2009;Liu et al 2013;Reemers et al 2012), which would be good for broader cross-protection (Brown and Kelso 2009) and wider population coverage (Sette and Sidney 1998). VP1:VP2C-M1-II was not pursued further due to complication in purification related to the presence of the previously reported aggregates.…”

“…Some of these have further been shown to be positive Human Leukocyte Antigen (HLA, human MHC) binders and elicit Tc immune responses (Alexander et al 2010;Assarsson et al 2008;Bui et al 2007;Heiny et al 2007;Parida et al 2007;Somvanshi et al 2008;Tan et al 2010;Wang et al 2007;Wang et al 2010a). The Tc-epitope commonly used to test a vaccine candidate is the matrix 1 (M1) protein M158-66 epitope (Table 1.…”

“…M1-II consists of M1-I in addition to the rest of the downstream amino acids of the N-terminal domain. Beside M158-66 epitope (further termed IT1 in this thesis), other epitopes covering a number of HLAs (Alexander et al 2010;Assarsson et al 2008;Babon et al 2009;Lee et al 2008;Liu et al 2013;Tan et al 2010;Wang et al 2007) (Berthoud et al 2011) Figure 1.2 M1 protein soluble domain and epitope distribution. 3D structure of influenza M1 soluble domain (PDB 1EA3SID) (A).…”