Abstract
Envelope proteins of the human immunodefiency virus (HIV) use the cell surface CD-4 molecule
of target cells to initiate infection which eventually lead to the acquired immunodeficiency
syndrome (AIDS). HIV-1 strains form three groups, namely the M, N and O, with the former
group further divided into at least ten equidistant subtypes or clades (i.e. A through J) classified
on the basis of sequence homologies in the envelope gene. Recombinant envelope proteins
expressed in transfected Chinese hamster ovary (CHO) cells were isolated and purified here (~
0.01 mg yield). An economical but efficient purification procedure using affinity chromatography
and freeze-drying was developed. The results obtained through SDS-PAGE, western blotting,
specific ELISA (using Galanthus nivalis a lectin with affinity for ENV glycoproteins) and partial
sequencing confirmed the purity (~ 85 - 90 %) and identity of the proteins. Since these proteins
were derived in a clade A (Uganda) and B (USA) environment we anticipated limited crossreactivity
with immune responses induced in a subtype C (RSA) environment. This was assessed
using ELISA (titers of 1000) and western blot analysis. The ability to induce apoptosis was used
to demonstrate functionality of the purified protein (Results showed that in-vitro induction of
apoptosis (65 %) using the continuous cell line PM1 was achieved).
Dr. Debra Meyer