The relationship between the soluble antigens and the virion of adenovirus type 3: IV. Immunological complexity of soluble components

Abstract

Rabbit hyperimmune sera were prepared against purified structural components of adenovirus type 3. Antihexon sera contained complement-fixing (CF) antibodies with group, intersubgroup, subgroup, and type specificity. The type-specific antibodies were highly active in neutralization tests and in hemagglutination-inhibition (HI) tests with virion-associated hemagglutinin (HA). No HI antibody reacting with soluble HA and no hemagglutination-enhancing (HE) antibody was demonstrable in antihexon sera. The capacity of the sera to inhibit virion-HA was interpreted as being due to steric interference between IgG antibodies attached to paravertex hexons and fibers, whereby the latter were prevented from interacting with receptors on red cells. Immunological characteristics of antibodies against vertex capsomeres were studied by use of antipenton sera absorbed with fibers. These antisera contained group, intersubgroup and subgroup-specific HE antibodies, which could combine penton incomplete HA's into hemagglutinating aggregates. No neutralizing or HI antibody activity was carried by these sera. Antifiber sera contained only type-specific antibodies. These antibodies were active in HI tests with both soluble and virion-associated HA and also somewhat in neutralization tests. Cross-absorption experiments demonstrated that neutralizing antibody induced by fibers was qualitatively different from that induced by hexons.