Attachment and eclipse of adenovirus.

The attachment and eclipse of adenovirus have been studied with the aid of highly purified (14)C-threonine and (32)P-labeled adenovirus type 2 in KB cells in suspension cultures. Adenovirus particles and infectivity appear to attach at the same rate. The attachment rate appears to be highly dependent on the cell concentration and less dependent on virus concentration within the multiplicity range from 0.15 to 3 plaque-forming units per cell, probably corresponding to 4.5 to 90 particles per cell. Subsequent to attachment, 5 to 8% of the (14)C label is eluted from the cell at a structure level, corresponding to free hexon. The (32)P activity is rapidly associated with the cells and is converted within 20 to 30 min to 65 to 85% deoxyribonuclease-susceptible material. This process is unaffected by actinomycin and puromycin. The deoxyribonuclease-sensitive material is, however, associated with (14)C label for an extended period after infection, and does not sediment as free deoxyribonucleic acid in sucrose gradients. The implications of these findings on the penetration mechanism of animal viruses are discussed.