Sequence similarity between the envelope surface unit (SU) glycoproteins of primate and small ruminant lentiviruses

Sequence similarity has been previously described in the transmembrane doma in unit of envelope glycoproteins of primate and non-primate lentiviruses b ut similarity between the surface unit (SU) glycoprotein of these viruses i s less clear or absent. Here we describe a consistent and significant seque nce-similarity between the ovine/caprine lentivirus surface glycoprotein gp 135 and the primate lentivirus gp120 in the region between variable loops V 2 and V3. The biological relevance of this sequence similarity was indicate d by clustering of conserved motifs in regions of structural importance in the human immunodeficiency virus type 1 gp120, conservation of cysteine res idue pairs forming disulfide bonds and similar patterns of sequence variati on in gp135 and gp120 between strains. The results indicate that SU glycopr oteins from primate and small ruminant lentiviruses have structurally relat ed domains. (C) 2000 Elsevier Science B.V. All rights reserved.