title: Immune camouflage: relevance to vaccines and human immunology.
abstract: High strain sequence variability, interference with innate immune mechanisms, and epitope deletion are all examples of strategies that pathogens have evolved to subvert host defenses. To this list we would add another strategy: immune camouflage. Pathogens whose epitope sequences are cross-conserved with multiple human proteins at the TCR-facing residues may be exploiting "ignorance and tolerance," which are mechanisms by which mature T cells avoid immune responses to self-antigens. By adopting amino acid configurations that may be recognized by autologous regulatory T cells, pathogens may be actively suppressing protective immunity. Using the new JanusMatrix TCR-homology-mapping tool, we have identified several such 'camouflaged' tolerizing epitopes that are present in the viral genomes of pathogens such as emerging H7N9 influenza. Thus in addition to the overall low number of T helper epitopes that is present in H7 hemaglutinin (as described previously, see http://dx.doi.org/10.4161/hv.24939), the presence of such tolerizing epitopes in H7N9 could explain why, in recent vaccine trials, whole H7N9-HA was poorly immunogenic and associated with low seroconversion rates (see http://dx.doi.org/10.4161/hv.28135). In this commentary, we provide an overview of the immunoinformatics process leading to the discovery of tolerizing epitopes in pathogen genomic sequences, provide a brief summary of laboratory data that validates the discovery, and point the way forward. Removal of viral, bacterial and parasite tolerizing epitopes may permit researchers to develop more effective vaccines and immunotherapeutics in the future.
authors.affiliation: a EpiVax Inc. ; Providence , RI USA.
authors.forename: Anne S
authors.initials: AS
authors.lastname: De Groot
authors.forename: Lenny
authors.initials: L
authors.lastname: Moise
authors.forename: Rui
authors.initials: R
authors.lastname: Liu
authors.forename: Andres H
authors.initials: AH
authors.lastname: Gutierrez
authors.forename: Ryan
authors.initials: R
authors.lastname: Tassone
authors.forename: Chris
authors.initials: C
authors.lastname: Bailey-Kellogg
authors.forename: William
authors.initials: W
authors.lastname: Martin
mesh_terms: D003429:Cross Reactions; D018984:Epitopes, T-Lymphocyte; D006801:Humans; D057131:Immune Evasion; D007108:Immune Tolerance; D064766:Influenza A Virus, H7N9 Subtype / Q000276:immunology; D011948:Receptors, Antigen, T-Cell / Q000502:physiology; D014612:Vaccines / Q000276:immunology*
chemical_list: D018984:Epitopes, T-Lymphocyte; D011948:Receptors, Antigen, T-Cell; D014612:Vaccines
keywords: Biologic; Deimmunization; EpiMatrix; HA, hemagglutinin; HCV, Hepatitis C virus; HIV, human immunodeficiency virus; HLA, human leukocyte antigen; IAVs, influenza A viruses; JanusMatrix; TCR, T cell receptor; Td response, T cell-driven response; Tolerance; Treg; Treg, regulatory T cell; Tregitope; Tregitope, Treg epitope; Vaccine; nTreg, natural regulatory T cells