Antigenicity of truncated forms of the human immunodeficiency virus type 1 envelope glycoprotein

1 Department of Chemistry, University of York, Heslington, York YO1 5DD, UK 2 School of Animal & Microbial Sciences, University of Reading, Whiteknights, PO Box 228, Reading, UK 3 Department of Biochemistry, University of Bristol, University Walk, Bristol BS8 1TD, UK 4 Celltech Ltd, 216 Bath Road, Slough, Bucks SL1 4EN, UK Chinese hamster ovary (CHO) cell lines secreting a series of truncated forms of human immunodeficiency virus type 1 (HIV-1) IIIB (clone BH10) gp120 were assembled. Using purified glyco-proteins, we demonstrated the functional and structural integrity of these truncates by their reactivity with both sCD4 and anti-gp120 monoclonal antibodies (MAbs). Deletion of the V1, V2 and V3 regions had minimal effects on CD4 binding, but deletion of the NH 2 terminus affected the folding of the truncated molecule. Deletion of either V1/V2 or V1/V2/V3 regions led to enhanced recognition by some, but not all, MAbs mapping to the CD4 binding site. In contrast, deletion of the V1/V2 regions had no effect on the ability of V3-specific MAbs to bind to the truncate. These results support the use of truncated forms of gp120 as components of potential HIV vaccines. Present address: AIDS Collaborating Centre, NIBSC, Blanche Lane, South Mimms, Potters Bar, Herts EN6 3QG, UK. Received 5 December 1995; accepted 12 February 1996.