The relationship between soluble antigens and the virion of adenovirus type 3 III. Immunological identification of fiber antigen and isolated vertex capsomer antigen

Abstract

A previously not identified soluble adenovirus type 3 component was demonstrated in zonal centrifugation and gel filtration experiments. It accumulated at a position intermediate between 7 S bovine γ-globulin and albumin. It was demonstrated by its capacity to absorb hemagglutination-inhibiting (HI) antibodies and to react in complement-fixation (CF) tests with an antiserum against complete HA. Treatment of incomplete HA (penton antigen) with trypsin or guanidine-HC1 brought about the release of this component. It is postulated to represent the fiber antigen, i.e., isolated vertex projections. The major fraction of components capable of absorbing hemagglutination-enhancing (HE) antibodies, which have been postulated to react with vertex capsomers of adenovirus type 3, were found to be associated with incomplete HA. Treatment of the latter with trypsin completely destroyed its capacity to interact with HE antibodies. In contrast, treatment with guanidine-HCl caused a breakdown into two components. One, as mentioned above, was identified with the postulated fiber antigen, whereas the other could absorb HE antibodies. The latter component sedimented slightly more slowly than hexon antigen, and small quantities of spontaneously occurring HE antibody absorbing material with the same sedimentation characteristics were also detected. It is suggested that this kind of product represents isolated vertex capsomers. Gel filtration on Sephadex G-200 was found to be a useful technique for isolation and purification not only of the postulated fiber antigen, but also of incomplete HA and hexon antigen. These two components were eluted separately, in the sequence incomplete HA and hexon antigen, with a position intermediate between the peals of 19 S and 7 S bovine γ-globulin. The postulated fiber antigen of adenovirus type 3 and the corresponding component of types 4 and 5, all of which have different lenghts, could also be effectively separated by gel filtration on Sephadex G-200.