Generation and characterization of monoclonal antibodies against multiple epitopes on the C‐terminal half of envelope gp46 of human T‐cell leukemia virus type‐I (HTLV‐I)

In order to study the antigenicity of envelope 46 kDa glycoprotein (gp46) of human T‐cell leukemia virus type‐l (HTLV‐I), we have generated monoclonal anti‐gp46 antibodies (MAbs), REY‐7, REY‐11, REY‐16, REY‐30, MET‐2 and MET‐3 from rats and mice. Immunoblot and immunofluorescence assays showed that these MAbs recognize gp46 and its related antigens, and specifically stained HTLV‐I‐bearing cells. All MAbs reacted with a recombinant gp46 antigen, NI47, expressing the 147 amino acids in the C‐terminal half of gp46. By using various synthetic peptides corresponding to the gp46 sequence, epitopes recognized by REY‐7 and MET‐3, REY‐11 and RE Y‐16, and REY‐30 were mapped to regions corresponding to the amino acids 175‐199, 253‐282 and 288‐312, respectively. MET‐2 did not react with any of the peptides used. These results indicate that the present MAbs are directed against at least 4 distinct epitopes expressed on the C‐terminal half of gp46. The binding of these MAbs to gp46 was specifically inhibited by sera from HTLV‐I‐infected individuals, but none of these MAbs inhibited the cell fusion activity of HTLV‐I.