Studies on adenoviruses (APC-RI-ARD) in tissue culture. Correlation between the amount of virus inoculated and the time needed for production of cellular degeneration

Respiratory viruses in a residential nursery

A longitudinal survey of respiratory illness in a Sheffield residential nursery is described. Over 8 months, outbreaks of respiratory illness occurred, two of which were associated with infection by Influenza A and Parainfluenza 3 viruses. The symptomatology is described of the illnesses resulting from these infections. The incidence of adenovirus recoveries over the same period was also investigated and suggests that adenoviruses of Types 1, 2 and 5 may be components of the normal viral flora of the nasopharynx in infants.

The kinetics of adenovirus infection and spread in cell cultures infected with low multiplicity

The cause for the long "incubation period" required till the appearance of the CPE in cell cultures inoculated with small amounts of adenovirus was investigated with adenovirus type 5 in HeLa cell cultures. The spread of virus in a culture from cell to cell is minimal, as shown in cultures with antiserum in the medium. The spread by spontaneously released virus via the medium is more important. It can be accelerated by repeated subcultivation after freezing and thawing the cells in 2 or 3 days' intervals. The quantity of virus produced by one infected HeLa cell was found to be 200 TCID50 within 48 hours, independent of the MOI. The growth cycle too is largely independent of the virus dose. The data suggest that the long duration of the "incubation period" is fully explained by a burst size of 200, a cycle length of 40 to 48 hours and the assumption of a slow and steadily working process of spontaneous release of virus into the medium. Some other possible causes, like impurities in the inoculum or slow and asynchronous early stages of infection, have been ruled out by appropriate experiments.