Mutations of Apathogenicity and Small Plaques In the Tick-Borne Encephalitis Virus Induced by N-Nitrosomethyl Urea

摘要

N-nitrosomethyl urea induces 100% mutations of apathogenicity in the virus of tick-borne encephalitis. The mutation from normal to small plaques are encountered 25% less frequently, and are not related to apathogenicity mutations. With respect to the degree of specificity, N-nitrosomethyl urea is superior to 1.4-bis-diasoacethyl butane, since the former evokes two types of mutation whereas 1.4-bis-diasoacethyl butane is characterized by three mutations. The nearly 100% mutation frequency brought about N-nitrosomethyl urea is achieved when the viability of the virus is decreased tenfold, and a 75% mutation frequency is obtained when the viability is decreased fivefold; this has never been observed up to now in experiments with other physical and chemical mutagens. (Author)