Antibodies to hepatitis B surface antigen (HBsAg) elicited by immunization with a synthetic peptide covalently linked to liposomes.

Peptides synthesized for potential application as antiviral vaccines have been mostly tested in the form of conjugates with carrier proteins. The possible use of several distinct synthetic vaccines in prophylaxis would be facilitated by the availability of fully synthetic immunogens. A synthetic peptide corresponding to residues 135 to 155 ( P135 -155) of hepatitis B surface antigen (HBsAg) failed to elicit in free form anti-peptide antibodies or anti-HBs. However, polymers of P135 -155 (prepared by linking to diaminoalkanes ) and synthetic conjugates prepared by binding P135 -155 to liposomes or polylysine were immunogenic. A poor correlation was observed between anti-peptide and anti-HBs responses elicited by these conjugates. Glutaraldehyde-fixed liposomes appeared to be the carriers of choice for inducing anti-HBs.