FIG. 4.

Schematic representation of the variable-region exchange chimeric envelope constructs. Neutralization-sensitive envelope from pony 564 febrile episode II (hatched bars) and neutralization-resistant envelope from pony 564 febrile episode V (solid bars) were used as reference envelope species for the variable-region exchanges. The names of the new variable-region exchange chimeric viruses are listed in italics at the left of each construct, starting with the name of the backbone followed by the exchanged variable region in parentheses. The gp90 envelope variable regions V1 to V8 are schematically identified above the bars.