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

Abstract

Summary

A strain of psittacosis virus (TTF) developed resistance to 5–flourouracil (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 μg FU/ml, at which level FU suppressed the original wild–type TTF virus completely. Reversion of character from FU–resistance to FU–sensi–tivity following serial passages 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.