Lentivirus antigen purification and characterization: isolation of equine infectious anemia virus gag and env proteins in one step by reverse phase HPLC and application to human immunodeficiency virus glycoproteins.

We describe here a one step HPLC technique for purifying the four gag proteins (p26, p15, p11 and p9) and two env glycoproteins (gp90 and gp45) from purified equine infectious anemia virus (EIAV), a member of the lentivirus subfamily of retroviruses. The purification procedure employs a reverse-phase phenyl Radial-pak cartridge contained in a high pressure radial compression chamber in which a shallow, multistep acetonitrile gradient is applied at ambient temperatures. The purified proteins are recovered at an efficiency of 60-70%. Moreover, the isolated components retain their antigenicity and are suitable for a variety of biochemical analyses including protein sequencing. The purification of EIAV gp90 and gp45 represents the first successful isolation of a lentivirus glycoprotein from purified virus preparations. The availability of these separated proteins permitted direct protein sequencing which confirmed the previously reported env gene sequence and provides important antigens for the development of diagnostic immunoassays and subunit vaccines. The procedures described appear applicable to other lentiviruses, including human immunodeficiency virus (HIV), and perhaps to hydrophobic membrane proteins in general.