NDV-H is a potent inducer of type I interferon in the cotton rat lung. An IFN-α/β bioassay was performed with BAL fluid to determine the levels of induction at days 1, 2, 3, 4, and 7 after intranasal inoculations with 105 PFU NDV-H or MV Schwarz. Differences at days 1, 2, and 3 were statistically significant (analysis of variance [ANOVA]). The results reflect the means of four animals per group plus standard deviations (SD).