RECOGNITION BY HUMAN SERA OF A VARIABLE REGION OF THE SURFACE GLYCOPROTEIN OF HTLV-I

The region comprised between the amino acids 175 and 199 of the HTLV-I envelope surface glycoprotein is one of the immunodominant domains of this molecule. In this region, which is well recognized by sera from HTLV-I infected patients, a substitution of the proline at position 19 2 by a serine has been described in some isolates. Because this mutati on could modify the secondary structure of the glycoprotein molecule, we studied the inference of the presence of proline or serine on the r ecognition of the region 175-199 by human sera. For this, three peptid es have been synthetized (a 25-mer 175-199 corresponding to the sequen ce of the ATK prototype, and two internal 10-mer 190-Pro-199 and 190-S er-199 having a proline or a serine at position 192) and tested by imm unosorbent assay. While most sera reacted with 190-Pro-199 and with 19 0-Ser-199 synthetic peptides, a differential recognition was observed according to the pathology associated to HTLV-I infection. Moreover se ra corresponding to patients infected with a virus harboring a serine at position 192 were found to recognize only the 10-mer with a serine. These data indicates that HTLV-I is subject to antigenic variability.