Bioactive fragment of human interleukin-1beta (163-171) modulates the immune response to synthetic peptides of RESA of Plasmodium falciparum.

In this study a bioactive fragment, residues 163-171 of human interleukin-1beta (hu IL-1beta), that mimics the functions of the whole IL-1 molecule was chemically linked to two peptide sequences of the ring erythrocyte surface antigen (RESA), an asexual blood stage antigen of Plasmodium falciparum. The immunogenicity of different formulations was studied in different haplotypes of inbred mice. The peptide-IL-1beta conjugates delivered in liposomes showed the maximal antibody production. Antigen entrapped in liposomes at a dose of 5 microg showed antibody levels comparable to that of peptide conjugate in alum. The IgG subclass profile with different RESA peptides and its conjugates at various doses in liposomes induced predominantly IgG2a/2b isotypes while alum-delivered formulations showed both IgG1 and IgG2a/2b isotypes. In vitro studies of merozoite reinvasion showed varying degree (50-85%) of inhibition, maximum being with the peptide conjugates in liposomes (80-87%). Thus, this approach suggests that linking of hu IL-1beta is instrumental in augmenting the immune response against otherwise poorly immunogenic synthetic peptides.