Synchrony and the Elimination of Chance Delays in the Growth of Poliovirus

Abstract

SUMMARYThe effect of multiplicity of infection on the growth kinetics of poliovirus suggests that the eclipse period usual for singly infected cells (3.6-3-8 hr) includes variable delays averaging about 1 hr. These delays are overcome at multiplicities above 3, and are sometimes spontaneously absent. They are ascribed largely to chance effects, and lead to markedly asynchronous maturation of virus ; in their absence, maturation is almost synchronous.The kinetics of acid-irreversible eclipse and of the development of antiserum resistance show that about half of the delays must occur during viral penetration; in support of this, virus growth initiated with infective RNA is 0.5 hr less delayed than that of intact virus, although otherwise similar. However, infective RNA synthesis was not detected earlier than 2 hr after infection, even in the absence of chance delays.

The Kinetics of the Appearance of Poliovirus Ribonucleic Acid

“…The eclipse period, as determined by assays of mature virus and infective centres (not shown), was 2.6 hr. This indicates that maturation was approximately synchronous (Cooper, 1964), and hence that all cells must have begun replication of viral RNA well before this time. More than 60% of the RNA found up to 2 hr was sensitive to ribonuclease when the cells were disrupted and treated with the enzyme before phenolic extraction.…”

“…This paper reports experiments on the rate of increase of poliovirus RNA under conditions lacking these complications. Random delays were largely absent so that maturation began almost synchronously (Cooper, 1964). Cells were infected with a light-sensitive inoculum (Wilson & Cooper, 1962).…”

“…per infective cell) were 24-2-7 hr and maturation was rapid and exponential. These criteria were regarded as essential to indicate the absence of random delays and asynchrony (Cooper, 1964). …”