Analysis of an adenovirus type 12 temperature-sensitive mutant defective in interferon induction

Among several temperature sensitive mutants of human adenovirus type 12 (Ad12), H12ts15 was found to be defective in induction of interferon (IFN) in chick cells. This mutant was characterized as late mutant which synthesized defective III.a and penton-base antigens and failed to assemble into infectious particles at restrictive temperature. Moreover, its defect was manifested at permissive temperature, at which defective particles were readily formed. Temperature shift experiments revealed that an early event, but neither virus adsorption nor penetration, was blocked in the process of IFN induction. Therefore, it can be assumed that conformation of the adeno virion is important for IFN induction in chick cells. Conformation alteration caused by defective structural components of the capsid at restrictive temperature prevented IFN induction. This change, however, did not affect infectivity under similar conditions.