An analysis of the growth curve obtained in vitro for influenza virus in chorioallantoic membrane has been made using two known viral inhibitors, methoxinine and α-amino-α p-methoxyphenylmethanesulfonic acid. The action of these compounds has been shown to be specific for particular phases of viral development. Further, this action is sequential indicating that the inhibited phases do not occur concurrently.
The sulfonic acid interferes with the initiation of infection and with the release of newly formed virus from the host-cell. The former effect is dependent upon the relative concentrations of viral inoculum and sulfonic acid. The latter effect is prevented by the action of the receptor-destroying enzyme obtained from cholera vibrio extracts. It is proposed that a function of the viral enzyme is to facilitate the release of virus from the host-cell. The intracellular concentration of virus necessary to initiate this release is increased in the presence of α-amino-α p-methoxyphenylmethanesulfonic acid.
It was found that infection can be initiated in the presence of methoxinine under which condition viral increase is disallowed. The function in viral development of one biochemical process which is inhibited by methoxinine was found to be completed at an interval after initiation of infection and before the appearance of the infectious form of the virus. It is possible to define four stages of viral development in terms of sensitivity to methoxinine and α-amino-α-p-methoxyphenylmethanesulfonic acid.