THE FIRST STEP: Making COS-env
cells
The first step is to create a line of hybrid cells that mimic HIV. Though the cells are not infectious themselves, they display HIV's gp 120 protein on their outer membranes.
How was this done? Simian fibroblastoid cells ( COS-7 ) were transfected to express functional envelope glycoproteins ( the transmembrane glycoprotein gp 41 and surface glycoprotein gp 120 ) from a primary HIV-1 isolate (168P).
This fusion-competent native complex was referred to as COS-env cells.