FIG. 4.
(A) Production of alpha/beta interferon in infected L929 cells. Cells were infected with the virus indicated at an MOI of 0.2 TCID50/ml for 48 h. Cell culture supernatants were treated for 24 h at pH 2, neutralized, and used for priming of fresh L929 cells. Interferon concentrations were calculated by using a standard curve of serial dilutions of alpha/beta interferon. (B) Production of beta interferon in infected HeLa cells. Cells were infected with the virus indicated at an MOI of 0.2 TCID50/ml for 48 h. Beta interferon production in cell culture supernatants was measured by enzyme-linked immunosorbent assay. Means and standard deviations from three independent experiments are indicated.