FIG. 5.

Detergent resistance of membrane-associated M1 from WSN virus-infected MDBK cells. (A and B) TX-100 treatment of membrane-associated M1 protein synthesized early (2.5 hpi) in the virus replication cycle. WSN virus-infected (MOI of 10) MDBK cells (5 × 10⁶) were labeled with 300 μCi at 2.5 hpi for 20 min (A) and chased for 3 h (B) in the presence of 1.0 mM cycloheximide. Cells were then harvested and fractionated, and membrane fractions were isolated from the 4K supernatant with a floatation gradient. The membrane fractions were then treated without (−) or with (+) 0.05% TX-100 and analyzed with a second floatation gradient. Fractions were immunoprecipitated and analyzed by SDS-PAGE. (C and D) Analysis of M1 protein synthesized late (6.5 hpi) in the virus replication cycle. WSN virus-infected MDBK cells were labeled with 300 μCi at 6.5 hpi for 20 min (C) and chased for 1 h (D) in the presence of cycloheximide as described above. Membrane fractions were isolated from virus-infected cells as described above, treated without (−) or with (+) 0.05% TX-100, and analyzed with a floatation gradient. Fractions were immunoprecipitated and analyzed by SDS-PAGE.