Postimmunization Clearance of Liposome Entrapped Adenovirus Type 5 Hexon

Abstract

Clearance rates of 125I-hexon administered in three different forms from injection sites were assessed in animals. Aqueous and liposome-entrapped hexons following parental administration were cleared in linear fashion with half-lives that ranged from 1.5 to 4 and 30 to 45 hr, respectively. In contrast, hexons emulsified in complete Freund's adjuvant were cleared in a biphasic manner and tended to remain localized with 23 to 55% persisting after 16 days. No significant antigen accumulation in blood or any internal organs was detected following the three modes of immunization. These data suggest that formation of a transient antigen “depot” at injection sites may contribute to the adjuvant effect of liposomes but the complete resolution of this “depot” may avoid significant local reactogenicity.