FIG. 4.
Examination of GP5 incorporated into mutant virions and synthesized in mutant virus-infected cells or in transfected cells. (A) Radiolabeled virions from culture supernatants of infected cells were pelleted, GP5 protein was immunoprecipitated, treated with Endo H (+) or not (−), and analyzed by electrophoresis. The positions of wt GP5 without and with Endo H digestion (lanes 1 and 2, respectively) are shown by white brackets. (B) Cells infected with various mutant viruses were radiolabeled, GP5 was immunoprecipitated, treated with Endo H (+) or not (−), and analyzed by electrophoresis. The positions of wt GP5 without and with Endo H digestion (lanes 2 and 3, respectively) are shown by white brackets. (C) Pulse-chase analysis and Endo H sensitivity of GP5 expressed in transfected cells. Cells were transfected with GP5-IE-M, pulse-labeled for 2 h (2hrP), and subsequently chased for 2 h (2hrC) or 4 h (4hrC). Proteins were immunoprecipitated with anti-GP5 antibody, digested with Endo H (+) or not (−), and analyzed by electrophoresis as described in Materials and Methods. (D) Pulse-chase analysis and Endo H sensitivity of GP5 in cells infected with wt PRRSV. The experiment was performed as in panel C. The mobility of proteins is shown in kilodaltons on the right side of each panel.