FIG. 1.

Baculovirus (BV)-infected Sf9 cells and cultured media from infected cells protect MEF from the cytopathic effects of VSV. Baculovirus-infected and uninfected Sf9 cells were grown at 27°C for 1 week. Sf9 cells and cultured media were collected and centrifuged. The cells were suspended in D−10+NEAA at 5 × 10⁶ cells per ml and disrupted by multiple freeze-thaw cycles. Similar results were obtained with baculovirus-infected Sf9 cells that had not undergone freeze-thaw (data not shown). Immortalized MEF were treated with serial dilutions of either baculovirus-infected or uninfected Sf9 cells or cultured media. After 24 h, the cells were washed and treated with VSV. Cells were monitored for cytopathic death and stained with crystal violet at ∼18 h after infection. Each point represents the mean of triplicate wells.