FIG. 1.

Schematic illustration of the glycoprotein expression constructs. The coding regions of the different envelope expression constructs used in this study are shown schematically. The viral origins of the glycoproteins (virus) and the construct names (construct) are indicated to the left of the schematic outline. The individual constructs are described in detail in Materials and Methods. Ampho, amphotropic; LP, leader or signal peptide; SU, surface domain; TM, transmembrane domain; MSD, membrane-spanning domain.