Factors Affecting the Propagation of Theiler's Gdvii Mouse Encephalomyelitis Virus in Tissue Cultures

Abstract

Summary The GDVII strain of Theiler's mouse encephalomyelitis has been carried through 50 serial passages in flasks of Simms' solution with minced brains of embryonic or one day mice; brains from mice as old as 9 days may be used. Temperature range for growth is 31–37 C; optimal pH is 7–9, the higher pH favors more rapid virus production. Culture flasks of medium and tissue stored for as long as 2 days at 5 C or 35 C before virus was added still yielded as much virus after incubation as if fresh tissue was used. Glucose increased yield of virus at pH 7 but not at pH 9. The following substances did not affect yield of virus in culture: CO, NH4Cl, NaF, Al, Cr, Sr, d-ribose, lactate, succinate, pyruvate, thiamine, riboflavin, nucleic acid, choline, alanine, phenylalanine, glutamic acid, thyroxin, sulfadiazine, para-aminobenzoic acid. The following substances decreased yield of virus, Mn, Zn, Fe, Cu, Co, Ni, NaCN, NaN3, iodoacetate and 2,4-dinitrophenol. Virus was also carried through 26 passages in tissue cultures of chick embryo brain but not other chick embryo tissues. Virus was passed 20 times in embryonated eggs of 8–16 days by intracerebral injection. Embryos usually survived without gross or histologic signs of infection.