BRANCHED POLYPEPTIDES AS ANTIGENS FOR INFLUENZA-VIRUS HEMAGGLUTININ AND T-CELL RECEPTOR SUBUNITS

The multiple antigenic peptide (MAP) method was applied to improve the immunogenicity of synthetic peptides representing distinct regions of the influenza virus hemagglutinin (HA). A tetrameric MAP with multipl y incorporated overlapping B-and T-cell epitopes was combined with a p articular HA sequence representing the slightly modified fusion peptid e on the C-terminus of the Lys core (MAP-1). As a result of repeated i njections of BALB/c mice with MAP-1 but not with the monomeric HA1C[Ar g] peptide, the appearance of MAP-1-specific antibodies crossreactive with the acid-pretreated virus could be observed. In vitro studies rev ealed the potency of the MAP-1 structure to induce proliferation of HA 1C[Arg]-primed T-cells, and in vivo studies demonstrated the protectiv e feature of the immune response elicited by MAP-1 and to a lesser ext ent by the monomeric HA1C[Arg]. The increased level of MAP-1-specific antibodies upon viral challenge shows the activation of MAP-1-specific B- and/or T-cells. The advantage of the previously verified FP3 helpe r T-cell epitope included in MAP-1 was further utilized to synthesize chimeric structures comprising short fragments of the zeta (MAP-2) or 8 (MAP-3) subunits of the T-cell antigen receptor (TCR) complex. The s elected peptides of the zeta- and delta-chain regions failed to elicit an antibody response in BALB/c mice as tetra- or octamers, but the in clusion of the modified fusion region resulted in an immunogenic const ruction. The chimeric MAP-2 and MAP-3 were successfully used to develo p polyclonal and monoclonal antibodies recognizing the corresponding m ultimeric peptides, but they were unable to bind to the cell membrane- expressed form of the subunits. The MAP constructions that were design ed, including appropriately selected B- and helper T-cell epitopes, we re proven to be immunogenic; but the crossreactivity of the induced an tibodies with the corresponding native proteins was highly dependent o n the individual characteristics of the resultant combinations.