FIG. 4.

Infectious virus isolated by coculture of activated PBMC from NIH miniature pig with ST-IOWA or human 293 cells. PBMC isolated from the NIH miniature pig were activated with PHA and PMA. Six days after activation, the cells were cocultured with ST-IOWA cells or human 293 cells. (A) Reverse transcriptase activity in cell culture medium removed at each of the days indicated. The mean values for counts per minute of [³H]TTP incorporated are shown on the y axis. The values for ST-IOWA cells cocultured with live PBMC are shown by closed circles, and those for ST-IOWA cells cocultured with lethally irradiated PBMC are shown by open circles. The results for the coculture of 293 cells with live PBMC are shown by closed squares, and those for 293 cells cocultured with lethally irradiated PBMC are shown by open squares. cpm, counts per minute. (B) Assay by RT-PCR followed by Southern blot analysis (described in Materials and Methods) of RNA obtained from 293 cells at the days indicated after coculture (numbers across the top) with either live PBMC (a), lethally irradiated PBMC (b), or control 293 (c) cultures. H, water only in lieu of cDNA template, a negative control for the PCR.