FIG. 8.

Protein quantification of affinity-purified coronavirus particles. LR7 cells were either mock infected, infected with MHV-WT, or infected with MHV-SGFP clone B. At 5 h p.i. cells were labeled for 1 h with ³⁵S-labeled amino acids and chased for another 2 h. Virus particles were affinity purified from the cleared culture medium with either the anti-M MAb (α-M MAb) or the anti-S MAb (α-S MAb) and analyzed by SDS-PAGE. The amounts of radioactivity in the M, S (total, i.e., S+S-GFP), and N proteins in the dried gels were determined by phosphorimager scanning. The ratios of the amounts of M to N, S to M, and S to N in affinity-purified MHV-SGFP relative to those in MHV-WT were calculated.