ImmuneEscapebyHumanImmunodeficiency VirusType1 fromNeutralizing Antibodies: Evidence forMultiple Pathways

Serafrommany HIV-1-infected individuals contain broadly reactive, specific neutralizing antibodies. Despite their broadreactivity, variant viruses, resistant toneutralization, can beselected invitro inthe presenceofsuchantisera. We havepreviously shownthatneutralization resistance ofan escapemutantwith an aminoacidsubstitution inthetransmembrane protein (A582T) occurs because ofalteration ofa conformational epitope thatisrecognized byneutralizing antibodies directed against theCD4binding site. In thisreport we demonstrate thatimmuneescape viaa single-amino-acid substitution (A281V) within a