STUDIES ON THE STREPTOMYCES ANTIBIOTICS EFFECTIVE AGAINST INFLUENZA VIRUS

Many antivirals which will inhibit the growth of influenza virus in tissue culture system have been isolated in this laboratory from various streptomyces filtrates. Though almost all of them, except myxoviromycin, did not have any chemotherapeutic effect against experimental influenza in mice, site of action of these compounds have been studied in order to get further information on the diverse action of various antivirals. The result obtained in such studies are the subject of this series paper.<br>In this particular communication, the site of action of streptothricin-3 was studied.<br>The host-virus system was maintained in an Erlenmeyer flask using 3ml of modified Hanks' solution as medium. Each flask contained 400mg of chorioallantoic membrane from 15 days embryonated egg. The PR8 strain was used thoughout the work. The amount of virus in the fluid was estimated both by determining the infectious titer in tissue culture system and heniagglutinin.<br>The result will be summarized as follows:<br>1) One mg/ml of streptothricin-3 was the minimum concentration which inhibited the viral growth completely when 10⁵ TCID₅₀ of virus was used as the inoculum. During the incubation at 37°C, the degradation of the substance was almost 30% within first 6 hrs.<br>2) Depending upon the inoculum size, the effect of the substance on the growth of virus varied.<br>3) Neither virocidal activity nor inhibition of the adsorption stage to the host has been observed with this substance.<br>4) The course of viral development was influenced even when the antibiotic was added as late as 10 hrs. after infection.<br>5) Incomplete reversibility of the action of the substance to the host cell was found when normal chrioallantoic membrane was treated with the substnce as long as 7 hrs. before infection.