STUDIES ON THE STREPTOMYCES ANTIBIOTICS EFFECTIVE AGAINST INFLUENZA VIRUS, 4 TH REPORT

As the preliminary study, growth characteristics of four viruses, i.e. influenza A (FMI), influenza B (Lee), Hemagglutinating virus of Japan (HVJ, Fushimi) and NewCastle disease virus (46-9674) have been examined in the tissue culture system using a piece of chorioallantoic membrane removed from 15-day old chick embryos as the host tissue. Among the four viruses tested, HVJ showed a characteristic growth curve when compared to the other three, i.e. long latent period for the cycle growth. The tissue culture system employed was also discussed with regard to its sensitivity of estimating alive virus particles, when compared to the egg infectivity titrations. In general, the former technic was more insensitive when compared to the latter in detecting particles and the difference lying between there two methods was most remarkable with HVJ.In the culture system described above myxoviromycin, two different kinds of streptothricins, sinanomycin (netropsin) and G-72 (chartreucin) were tested for their activity to inhibit the virus growth. When the per cent inhibition was plotted on the ordinate against the log concentration of any drug on the abscissa, characteristic inhibition curve was obtained with each antibiotics. However, in order to inhibit the growth of four viruses, the concentration required with each antibiotics was almost in the same order. With higher inoculum size in the tissue culture system described above, higher concentration of myxoviromycin was necessary to inhibit the growth. However, the fact was not the case with the remaining antibiotics.