Liposome entrapment and immunogenic studies of a synthetic lipophilic multiple antigenic peptide bearing VP1 and VP3 domains of the hepatitis A virus: a robust method for vaccine design

Abstract

Multiple antigen peptides (MAP) have been demonstrated to be efficient immunological reagents for the induction of immune responses to a variety of infectious agents. Several peptide domains of the hepatitis A virus (HAV) capsid proteins, mainly VP1 and VP3, are the immunodominant targets for a protective antibody response. In the present study we analyse the immunogenic properties of a tetrameric heterogeneous palmitoyl-derivatised MAP containing two defined HAV peptide sequences, VP1(11–25) and VP3(102–121), in rabbits immunised with either Freund’s adjuvant or multilamellar liposomes. The immune response was evaluated with a specific enzyme immunoassay using MAP[VP1+VP3], VP1 and VP3 as targets. The avidity of the immune response was measured by a non-competitive enzyme-linked immunosorbent assay and by the surface plasmon resonance technology. Antisera raised against the lipo-MAP peptide entrapped in liposomes demonstrated high avidity of binding with affinity rate constants approximately one order of magnitude greater than those obtained with the Freund’s protocol.