THE BOVINE LEUKEMIA-VIRUS (BLV) ENVELOPE GLYCOPROTEIN GP51 AS A GENERAL-MODEL FOR THE DESIGN OF A SUBUNIT VACCINE AGAINST RETROVIRAL INFECTION - MAPPING OF FUNCTIONAL SITES THROUGH IMMUNOLOGICAL AND STRUCTURALDATA

Further advances in retroviral vaccine development require a better un derstanding of the antigenic structure of the envelope complex which i s directly involved in infectivity events such as receptor recognition and membrane fusion. To design an optimal vaccine against BLV infecti on, we chose an approach based on the use of synthetic peptides coveri ng 78% of the gp51 sequence in order to select only those segments tha t could induce a protective response via cellular and humoral immunity . On the other hand, we built a model of the BLV env glycoprotein 3D o rganization, based upon the very sensitive hydrophobic cluster analysi s (HCA). The major information highlighted from this model is that the two loops, against which the most efficient neutralizing antipeptides antibodies are directed against, are in close proximity at the top of the ''head'' and could represent a potential site for receptor bindin g, These two peptides are of particular interest since they induce als o a helper T-cell response. We further propose that the BLV envelope g lycoprotein oligomerizes as a trimer.