Résumé : Nearest neighbor relationships between lipid and protein as well as between high-molecular-weight viral RNA and protein were investigated in bovine leukemia virus (BLV) particles using chemical crosslinking reagents. Separation of dimethyl suberimidate (DMS) induced lipid-protein complexes by sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed that the phosphoprotein pp 15 is linked to the lipid bilayer of the virus. By use of diepoxybutan (DEB) as crosslinking reagent p 12 and again pp 15 were found to be linked to the viral RNA. Based on these results and our previous data describing the spatial relationships of major structural proteins within BLV particles, a structural model of BLV is proposed. © 1984.