AbstractsBiology & Animal Science

The development of the Lee strain of type B influenza virus was shown to be inhibited by puromycin in tissue culture of the chick embryo chorioallantoic membrane. The compound is an antibiotic of unique structure which has been reported to possess a broad range of biological activity against unicellular and multicellular organisms. Investigations were carried out to examine the extent of inhibition induced by puromycin and to discover possible explanations for its antiviral activity. Puromycin caused complete inhibition of Lee influenza virus development in tissue cultures at a concentration of 8.0 micrograms per ml, marked inhibition at 4.0 micrograms per ml, and significant inhibition at 2.0 micrograms per ml. The compound inhibited the formation of infectious virus in tissue cultures, as well as virus hemagglutinin. At a concentration of 4.0 micrograms per ml it caused inhibition of cell growth, but did not block all metabolic activity. In vitro experiments indicated that the compound was not virucidal and did not influence the end point of the hemagglutination reaction. At a concentration of 4.0 micrograms per ml it did not interfere with the adsorption of virus to the chorioallantoic membrane in vitro. The combination of L-canavanine plus puromycin showed a synergistic effect on the inhlbition of virus development in tissue cultures. Combinations of ribonuclease plus puromycin, benzimidazole plus puromycin and m-tyrosine plus puromycin showed additive effects on virus inhibition in tissue cultures. None of a group of purines, pyrimidines or their nucleosides or nucleotides was able to reverse the inhibition caused by puromycin in tissue cultures. A dose of 1.0 mg of the compound administered twice daily for three days did not interfere with the development of influenza virus in mouse lung. The amino nucleoside of puromycin not only failed to inhibit the virus but actually gave a significant enhancement of virus yield in tissue culture fluids at a concentration of 0.20 mg/ml. Concentrations of 0.40 mg and 0.10 mg per ml caused a significant increase of the virus concentration in the culture fluid. This proved that the amino acid moiety of the molecule is necessary for the inhibition of influenza virus. It appears from the results obtained that the inhibition of virus development induced by puromycin may be due to its interference with normal synthesis or utilization of metabolites essential for the multiplication of the host cell and of the virus, possibly the synthesis of protein.