TABLE 1.

Interferon assay^a

Time (h)	IFN titer of virus
	Adapted	Initial
12	<4	<4
24	<4	<4
36	<4	16
48	<4	32
72	16	32

^aD2F2/E2 cells were infected with the initial or adapted virus at an MOI of 0.001. At various times, supernatant was harvested and assayed for IFN titer. Results are from one representative experiment.