English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

SUMMARY: Study of the dose-response curves in titrations of adenovirus type 5 in cultures of HeLa cells suggests two different mechanisms of cytopathic effect. A late effect, caused by relatively small virus doses, is considered to be a manifesta- tion of virus infectivity and is in good agreement with the hypothesis of independent action of virus units in the initiation of infection. The early effect, on the other hand, requires large virus doses and is considered to be of a toxic nature. Infective and toxic properties of adenovirus type 5 are distinguished by the greater sensitivity of the latter to inactivation by ultraviolet light. The methods used for infectivity titrations of adenoviruses are based on the cytopathic action of these agents in tissue cultures. Titration techniques described by different workers vary in several respects but in most cases the results are based on quanta1 responses in cultures incubated for a given period. A relationship between virus dose and time of onset of cytopathic effect has been described (Rowe, Huebner, Gilmore, Parrott & Ward, 1953), and Kjellen (1956) developed a method of titration based on the latent period which precedes the cytopathic effect. In the course of repeated titrations of adenovirus preparations we observed a difference between the slopes of dose-response curves of titrations read after varying periods of incubation. These differences suggest that the early effect of adenoviruses in HeLa cell cultures is of the nature of a toxic action, whereas the late effect is a manifestation of the infective property of the virus resulting from the independent action of single infective units. Studies on the dose-response curves of bacterial and virus titrations have been extensively reviewed and discussed (Beard, Sharp & Eckert, 1955; Bryan, 1955; Isaacs, 1957; Lauffer & Price, 1945; Luria, 1940; Meynell & Stocker, 1957). In most infectivity titrations the log dose-probit response curves show a slope equal to or lower than 2 (Peto, 1953), this being approximately the slope of the first term of the Poisson distribution (the ' one-particle curve '). This finding is generally accepted as evidence for the hypothesis of independent action of infective units, a single unit being sufficient to initiate infection. Deviations from the one-particle curve are attributed to variations in host susceptibility which cause a flattening of the curves. This is particularly evident with agents such as the tumour viruses where variation in host susceptibility greatly affects the slope of dose-response curves (Bryan, 1954; Beard et al. 1955). With bacteriophages, on the other hand, where host susceptibility is uniform, agree- ment with the one-particle curve is good (Feemster & Wells, 1933; Luria,

Dose-response Curves of Toxic and Infective Actions of Adenovirus in HeLa Cell Cultures