Open AccessEnvelope Glycoprotein Determinants of Increased Fusogenicity in a Pathogenic Simian-Human Immunodeficiency Virus (SHIV-KB9) Passaged In Vivo
Author(s) -
Bijan Etemad-Moghadam,
Yu Sun,
Emma Nicholson,
Maria da Luz Fernandes,
Kwa Liou,
Raul Gomila,
Juliette Lee,
Joseph Sodroski
Publication year - 2000
Publication title -
journal of virology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.617
H-Index - 292
eISSN - 1070-6321
pISSN - 0022-538X
DOI - 10.1128/jvi.74.9.4433-4440.2000
Subject(s) - ectodomain , biology , gp41 , syncytium , glycoprotein , chemokine receptor , v3 loop , virology , viral envelope , viral entry , in vivo , chemokine , microbiology and biotechnology , virus , receptor , antibody , immunology , biochemistry , viral replication , genetics , epitope
Changes in the envelope glycoprotein ectodomains of a nonpathogenic simian-human immunodeficiency virus (SHIV-89.6) that was serially passaged in vivo have been shown to be responsible for the increased pathogenicity of the resulting virus, SHIV-KB9 (G. B. Karlsson, et al., J. Exp. Med. 188:1159–1171, 1998). The 12 amino acid changes in the envelope glycoprotein ectodomains resulted in increased chemokine receptor-binding and syncytium-forming abilities. Here we identify the envelope glycoprotein determinants of these properties. A single amino acid change in the gp120 third variable (V3) loop was both necessary and sufficient for the observed increase in the binding of the SHIV-KB9 gp120 glycoprotein to the CCR5 chemokine receptor. The increased syncytium-forming ability of SHIV-KB9 involved, in addition to the V3 loop change, changes in the second conserved (C2) region of gp120 (residue 225) and in the gp41 ectodomain (residues 564 and 567). The C2 and gp41 ectodomain changes influenced syncytium formation in a cooperative manner. Changes in the V1/V2 gp120 variable loops exerted a negative effect on syncytium formation and chemokine receptor binding, supporting a previously described role of these changes in immune evasion. The definition of the passage-associated changes that determine the efficiency of chemokine receptor binding and membrane fusogenicity will allow evaluation of the contribution of these properties to in vivo CD4-positive lymphocyte depletion.