Interference in Cortisone-Treated Hosts. ∗

Discussion and Summary

The results reported herein have shown that prior injections of cortisone in embryonated eggs subsequently given minimal completely interfering doses of inactivated virus followed by challenge virus resulted in yields of viral hemagglutinins which were 7- to 10-fold greater than that found in untreated eggs. All 3 concentrations of cortisone (2.5, 5 and 7.5 mg) utilized in these experiments appeared to be equally effective in this respect.

An enhanced growth of influenza viruses in cortisone-treated eggs has been described previously (4), and the viral concentration of pooled allantoic fluids from cortisone-treated eggs was shown to be 123 to 155% of the viral concentration of control eggs (for influenza A virus). In the interference experiments reported in this paper, the yield of virus in cortisone-treated eggs was 700 to 1000% of the yield in untreated embryos. In view of this discrepancy in the increased yields of virus in the two reports, it would appear that enhancement of reproduction of challenge virus in residual free cells not blocked by interfering virus was not the sole determining factor in the increased yield of virus reported in this paper.