A HEMAGGLUTININ-BASED MULTIPEPTIDE CONSTRUCT ELICITS ENHANCED PROTECTIVE IMMUNE-RESPONSE IN MICE AGAINST INFLUENZA-A VIRUS-INFECTION

Multipeptide constructs, comprising adjacent sequences of the 317-341 intersubunit region of immature influenza A hemagglutinin (H1N1), were designed and the functional properties of these branched peptides wer e compared to that of the corresponding linear peptides. In vivo studi es revealed that the immunogenicity of the peptides was dependent on t he presence of the hydrophobic fusion peptide (comprised in FP3), enco mpassing the N-terminal 1-13 sequence of the HA2 subunit. Antibody and T cell recognition, however, was directed against the 317-329 HA1 seq uence, comprised in the P4 peptide. Multiple copies of P4, covalently linked by branched lysine residues, significantly enhanced the efficie ncy of antibody binding and the capacity of peptides to elicit B- and T-cell responses. A fraction of peptide induced antibodies reacted wit h immature or with proteolitically cleaved hemagglutinin (HA) molecule s pretreated at low pH. Immunization with a multipeptide construct, (P 4)(4)-FP3, not only resulted in elevated antibody and T cell responses but conferred enhanced protection against lethal A/PR/8/34 (H1N1) inf ection as compared to its subunit peptides. The beneficial functional properties of this artificial peptide antigen may be acquired by multi ple properties including: (i) stabilized peptide conformation which pr omotes strong, polyvalent binding to both antibodies and MHC class II molecules; (ii) appropriate P4 conformation for antibody recognition s tabilized by the covalently coupled fusion peptide, resulting in the p roduction of virus cross reactive antibodies which inhibit the fusion activity of the virus; (iii) activation of peptide specific B cells wh ich potentiate antigen presentation and peptide specific T cell respon ses; and (iv) generation of helper T cells which secrete lymphokines a ctive in the resolution of infection. (C) 1998 Elsevier Science B.V. A ll rights reserved.