INFLUENCE OF TISSUE CULTURE PASSAGE ON VIRULENCE OF FOOT-AND-MOUTH DISEASE VIRUS FOR MOTHER MICE.

Campbell, Charles H. (Plum Island Animal Disease Laboratory, Greenport, N.Y.). Influence of tissue culture passage on virulence of foot-and-mouth disease virus for mother mice. J. Bacteriol. 86:593-597. 1963.-Foot-and-mouth disease virus serially passaged in bovine cell cultures was more lethal for mother mice than the parent virus from infected steers. In tests with virus from several pools of bovine tongue tissue, only 0 to 20% of the mice died. Serial passage of such virus in primary calf-kidney cell cultures progressively increased the lethality of the virus. By the eighth passage, after which no further appreciable increase was observed, the mortality was 60%. As the lethal capability of this virus population increased, the average time required for it to produce death decreased.