Analysis of the expression and incorporation into pseudotyped retroviruses of Ebola virus GPs with substitutions eliminating sites of N-linked glycosylation. Analysis was conducted as described in the legend to Fig. 4, except that no PNGase F was used. The migration positions of mature GP1, GP0 (the glycosylated but uncleaved form), GPpre (the N-glycosylated but not O-glycosylated uncleaved form), and GP2 are indicated. WT, wild type; Neg, ΦNX cells transfected with pcDNA3 vector.