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132 Antigenicity of a Recombinant Envelope Glycoprotein Derived from a Primary Isolate of HIV-1 Collected during Primary Infection
L. Dacheux1, F. Lemiale1, Y. Ataman-Onal2, B. Verrier2, D. Brand1, and F. Barin*1
1Univ. F Rabelais, Tours, France and 2Ecole Normale Supérieure, Lyon, France
Background: Neutralizing epitopes are differently expressed at the surface of TCLA viruses and primary isolates (PIs). We studied the exposure of highly conserved neutralizing epitopes on recombinant envelope glycoproteins derived from PIs.
Methods: We studied the recombinant envelopes from 10 PIs and 2 T-cell line-adapted (TCLA) strains. Env genes were amplified by PCR and then cloned and expressed using the Semliki Forest Virus (SFV) vector. Antigenicity was studied by RIPA and capture ELISA using neutralizing monoclonal antibodies (mAbs: IgG1b12, 2G12, and 2F5) and human sera from patients whose genotype of infecting strain was known.
Results: The neutralizing epitopes corresponding to the mAbs were irregularly presented. We observed that 1 gp120 from a clade B PI (gp160133) had particular antigenic properties. Its corresponding env gene was isolated during a primary infection. The gp160133 was not bound by IgG1b12 and weakly bound by 2G12 and 2F5. The mature extracellular gp120133 was not bound by mAbs IgG1b12 and 2G12. In contrast gp120133 was the most strongly bound by all the human sera. This observation was confirmed with 4 additional clones of the env gene derived from the same early sample (133).
Conclusions: One envelope, derived from a PI isolated during primary infection, was highly antigenic when probed by human sera although weakly bound by neutralizing mAbs. This observation should lead to further characterization of envelopes derived from viruses isolated at an early stage of infection. These studies may provide insight into the way in which early viruses mask neutralizing epitopes while exposing irrelevant epitopes.
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