Titration of adenovirus by counting cells containing virus-induced inclusion bodies

Genetic Analysis of Adenovirus Type 2 II. Preliminary Phenotypic Characterization of Temperature-Sensitive Mutants

The properties of temperature-sensitive mutants of adenovirus type 2 representing 12 complementation groups were studied. All mutants were normal with respect to adsorption as measured by viral inclusion formation and viral DNA synthesis as shown by velocity sedimentation in alkaline sucrose gradients. One mutant, however, formed viral inclusions of altered morphology at the nonpermissive temperature. The synthesis of the major capsid proteins was examined by immunodiffusion. On this basis, the complementation groups could be arranged as follows: (i) one group was negative for all three proteins; (ii) three groups failed to synthesize penton bases; (iii) eight groups were positive for hexons, pentons, and fibers. The assembly of virus particles at 39 C was examined by equilibrium sedimentation in CsCl; three groups were found defective, whereas two of the penton-negative groups were positive for virion production. Tests of the thermolability of virions at 50 C revealed eight groups labile whereas the remainder were insensitive to heat inactivation. None of five mutants inoculated in newborn rats induced tumors, although three of them were capable of in vitro transformation.

Morphological method for estimation of simian virus 40 infectious titer

The cytomorphologic method previously reported for titration of adenoviruses has been employed for estimating the infectious titer of simian virus 40 (SV 40). Infected cells forming intranuclear inclusions were determined. The method examined possesses a number of advantages over virus titration by plaque assay and cytopathic effect. The virus titer estimated by the method of inclusion counting and expressed as IFU/ml (Inclusion Forming Units/ml) corresponds to that estimated by plaque count and expressed as PFU/ml.

Genetic analysis of adenovirus type 2. I. Isolation and genetic characterization of temperature-sensitive mutants

Temperature-sensitive mutants which replicate normally at 33 C but poorly at 39 C were isolated from nitrosoguanidine- or nitrous acid-mutagenized adenovirus 2 by (i) testing the cytopathic effect or inclusion body-forming capacity of random plaque isolates, or (ii) reduced plaque enlargement upon shifting from 33 to 39 C. Thirty-six mutants were isolated with 33 C/39 C plaque ratios varying from 20 to 10-5. Some of these mutants could be arranged into 13 groups by the complementation test. By means of recombination analysis a provisional linear genetic map was constructed.