POLY[DI(CARBOXYLATOPHENOXY)PHOSPHAZENE] (PCPP) IS A POTENT IMMUNOADJUVANT FOR AN INFLUENZA VACCINE

The adjuvant activity of poly[di(carboxylatophenoxy)phosphazene] (PCPP ) on the immunogenicity of formalin-inactivated influenza virions and commercial trivalent influenza vaccine was studied. Regardless of whic h antigen preparation is used, the addition of 100 mu g PCPP enhances the HAI antibody response 10-fold over the levels elicited by the vacc ine alone. Similarly, PCPP enhanced the IgM, IgG, and IgG1 ELISA antib ody titers to influenza antigens at least 10-fold higher than the vacc ine alone. In contrast, the IgG2a isotype titers were only enhanced ab out 2-fold, Immunization of aged mice (22 months old) with trivalent i nfluenza vaccine alone did not seroconvert these mice as measured by H AI or ELISA whereas significant sere-conversion was achieved when mice were immunized with PCPP-formulated trivalent vaccine. The adjuvant a ctivity of PCPP was shown to not be due to a site of injection depot e ffect. PCPP adjuvanticity was positively correlated to the molecular w eight of the polymer. (C) 1997 Elsevier Science Ltd.