Comparison between soluble components of adenovirus types 3 and 16 and of the intermediate strain 3–16 (the San Carlos Agent)

Abstract

The San Carlos agent, an adenovirus (type 3–16) sharing characteristics of type 3 by neutralization and of type 16 by hemagglutination inhibition (HI) tests, has been compared with types 3 and 16 with regard to physical-chemical properties of different structural components. No marked differences were found between the properties of isolated hexons, pentons (i.e., the incomplete hemagglutinin, HA, demonstrable in the presence of heterotypic immune sera), and fibers (i.e., the slowly sedimenting HI antibody-consuming components) of the three materials. However, the soluble complete HA's exhibited markedly different characteristics. The results indicate that they are carried by the following subunit aggregates: type 3—dodecahedral aggregates of pentons plus some extra structure; type 3–16—smaller polymers (probably dimers) of pentons; type 16—small polymers (probably dimers) of pentons or of fibers. Some members of Rosen's subgroup III (types 1, 2, 5, 6) show soluble complete HA subunit activities qualitatively similar to those of type 16. Soluble complete HA's containing small polymers of pentons were distinguished from those containing only fibers by the following properties; (a) a more rapid rate of sedimentation, (b) presence of toxin (cell-detachment) activity, (c) sensitivity to trypsin treatment, (d) presence of vertex capsomer antigen demonstrable by its hemagglutination enhancement antibody-consuming activity, and (e) a marked enhancement of the HA activity in the presence of heterotypic antisera.