Development of a Strain of Psittacosis Virus Partially Resistant to 5-Fluorouracil in a Tissue Culture System.

Abstract

A strain of psittacosis virus (TTF) developed resistance to 5-fluorouracil (FU) after serial passages of the original FU-sensitive virus in tissue culture cells with small concentration of FU in the medium. The FU-resistant strain of TTF virus multiplied and produced more than 105 infective units per ml in presence of 2 [mu]g FU/ml, at which level FU suppressed the original wild-type TTF virus completely. Reversion of character from FU-resistance to FU-sensitivity following serial passage in FU-free medium was not observed. This suggests that the acquisition of FU-resistance is due to certain gene mutation(s), rather than to enzymatic adaptation.