INFLUENCE OF CHEMICAL AND PHYSICAL MUTAGENIC FACTORS ON THE VIRUS of tick-BORNE ENCEPHALITIS
FORT DETRICK FREDERICK MD
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The possibility of obtaining variants of the tick-borne encephalitis virus under the influence of certain chemical and physical agents was studied. In experiments the chemicals azouridine, azouracil, 5-bromuracil, formaldehyde, urethan and proflavine were used as mutagenic agents. The influence of certain mutagenic factors on the vegetative virus of tick-borne encephalitis either sharply lowers the virulence of the causative agent tests with formaldehyde, or immediately lowers the peripheral activity of the virus tests with 5- bromuracil, or the peripheral activity of the virus is lowered with passaging tests with proflavine. Subject to further study is the problem of the reversibility of these properties, and also the fixing of these features and obtaining of pure lines of virus with reduced virulence. In addition to the influence of chemical mutagenic factors, the virus of tick-borne encephalitis was subjected to ultraviolet irradiation. Virus of the 5th passage after irradiation in a comparison with control had the cytopathogenic activity, but the incubation period of disease in mice during intracerebral infection for the control virus was 5.5 days, and for irradiated - 8 days. From these first results it is clear that under the stated conditions there is a possibility of multiple reactivation of the tick-borne encephalitis virus, and also the obtaining of different variants of this virus.