Characterization of the Secreted, Native gp120 and gp160 of the Human Immunodeficiency Virus Type 1

Abstract

We have previously shown that the cell line 6D5(451) chronically infected with the HIV-1 isolate HTLV-III(451), secretes the HIV-1 envelope glycoproteins gp120 and gp160 in the extracellular medium. The HTLV-III(451) gp120 and gp160 were purified by sequential affinity chromatographic steps using a monoclonal antibody to HIV-1 gp41 and an anti-HIV-1-positive human serum. Amino acid sequence analysis of gp120 and gp160 showed the loss of the signal peptide. Digestion of the purified gp120 and gp160 with endoglycosidases revealed that both proteins are heavily glycosylated and contain complex carbohydrates, in contrast to the intracellular form of gp160 which has been shown to contain mannose-rich immature sugars. Competitive binding analysis showed that while both gp120 and gp160 bind CD4, the affinity of gp160 was five times lower than that of gp120. Both gp120 and gp160 inhibited syncytia formation by HIV-1-infected cells when mixed with CD4+ cells. Furthermore, both gp120 and gp160 had strong mitogenic effects on the T cells from HIV-1-infected gibbons but not on cells from uninfected gibbons.

A Replication Competent Adenovirus 5 Host Range Mutant-Simian Immunodeficiency Virus (SIV) Recombinant Priming/Subunit Protein Boosting Vaccine Regimen Induces Broad, Persistent SIV-Specific Cellular Immunity to Dominant and Subdominant Epitopes in Mamu-A*01 Rhesus Macaques

“…4 An additional Ad5hr-SIVgag recombinant carrying a rev-independent SIV mac239 gag gene (33) has been described elsewhere. 3 Native gp120 was purified from a productive tissue culture medium as previously described for HIV-1 gp120 (34). An SIV polypeptide representing covalently joined repeating 18-mer amino acid segments homologous to the CD4 binding region of SIV mac251 gp120 was synthesized as previously described (20,35,36).…”

Concordant Modulation of Neutralization Resistance and High Infectivity of the Primary Human Immunodeficiency Virus Type 1 MN Strain and Definition of a Potential gp41 Binding Site in gp120

“…The neutralization epitopes that are functional on primary envelopes tend to be conformation dependent (9,16,40). Accessibility of some of the epitopes depends on conformational changes that occur after engagement of CD4 (39,40).…”

Extensive C-terminal Deletion in Human Immunodeficiency Virus Type 1 Env Glycoprotein Arising After Long-term Culture of Chronically Infected Cells

“…'Spontaneous' secretion of gp160 by a chronically infected cell line (Kalyanaraman et al, 1988(Kalyanaraman et al, , 1990, and more recently secretion of a similarly truncated gpl60 (Hallenberger et al, 1993;Owens et al, 1994), have also been reported. In addition, unprocessed gpl60 may also be present on virions, especially when the cytoplasmic tail is shortened due to insertion of a translational stop in the env gene (Dubay et al, 1992).…”