A virosome vaccine antigen delivery system does not stimulate an antiphospholipid antibody response in humans

A virosome vaccine delivery system comprised of the hemagglutinin of influenza A virus incorporated into unilamellar liposomes consisting of phosphatidylethanolamine (PE) and phosphatidylcholine (PC) or only PC was developed. The anti-PE and anti-PC antibody response was determined for human volunteers immunized with a virosome-formulated vaccine against hepatitis A, or a standard or virosome-formulated influenza vaccine. None of the 100 young adults who received two doses of the hepatitis A vaccine 1 year apart mounted a significant (greater than fourfold) antiphospholipid antibody response. Immunization with a single dose of trivalent influenza vaccine engendered a significant anti-PC and anti-PE antibody response in 1 of 32 elderly nursing home residents who received the virosome-formulated influenza vaccine and in 1 of the 31 residents who received a commercial subunit vaccine. These findings indicate that the virosome system can potentiate the human immune response to vaccine antigens without a concomitant rise in antiphospholipid antibodies.