The effect of liposomal charge on the neutralizing antibody response against inactivated encephalomyocarditis and Semliki Forest viruses.

The primary neutralizing antibody response to encephalomyocarditis (EMC) virus and Semliki Forest virus (SFV) is enhanced by addition of either negatively or positively charged liposomes. The purified u.v. light inactivated viruses were merely mixed with liposomes and injected intraperitoneally (i.p.) into mice. In contrast, neutral liposomes were unable to enhance the primary response to these viruses. Furthermore primary immunization with inactivated SFV mixed with either neutral, positively or negatively charged liposomes was associated with an enhancement of the secondary humoral response after i.p. booster injection of mice with inactivated virus alone. But neutral liposomes seemed to be less effective in this respect than either positively or negatively charged liposomes.