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The Development of Resistance to a Quinoxaline N-Oxide in Feline Pneumonitis Virus
Rima M. Greenland and James W. Moulder
The Journal of Infectious Diseases
Vol. 102, No. 3 (May - Jun., 1958), pp. 294-299
Published by: Oxford University Press
Stable URL: http://www.jstor.org/stable/30098412
Page Count: 6
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A strain of feline pneumonitis virus resistant to 2,3-dimethyl-quinoxaline-1, 4-dioxide was produced by five serial passages in the chick embryo yolk sac in the presence of the drug. The fully resistant virus was unaffected by doses of the drug which increased the mean survival time of embryos infected with parent virus by more than 5 days. This rapid increase in resistance suggests a higher rate of mutation than has been observed with other agents which inhibit the growth of the psittacosis group of viruses. Resistance to the quinoxaline oxide did not change during repeated drugless passage at high virus concentration. The level of drug resistance increased in three definite steps. When strains of resistant virus representing two of these levels of resistance were passed by the limiting dilution technique in the absence of the quinoxaline oxide, each resulting population exhibited the same degree of resistance as the strain from which it was derived, indicating a relatively homogeneous level of resistance at each step. It was concluded that feline pneumonitis virus probably becomes resistant to the quinoxaline oxide by a mechanism similar to that responsible for resistance to penicillin in bacteria. Quinoxaline oxide resistance has many features which recommend it as a marker in genetic studies with the psittacosis group of micro-organisms.
The Journal of Infectious Diseases © 1958 Oxford University Press