IMMUNOGENICITY OF VARIABLE REGIONS OF THE SURFACE ENVELOPE GLYCOPROTEIN OF HTLV TYPE-I AND IDENTIFICATION OF NEW MAJOR EPITOPES IN THE 239-261-REGION

The reactivity of sera of 96 individuals infected with human T-cell le ukemia virus type I (HTLV-I) was tested against various synthetic pept ides corresponding to the gp46 immunodominant antigenic domains: resid ues 86-107, 175-199, and 239-261. The frequency of reactive sera was h igher for 175-199 (93%) than for 239-261 (78%) or 86-107 (24%) with so me variations in geographical regions and in diseases, The region 239- 261 was extensively analyzed and five (linear or conformational) epito pes were found, The reactivity of sera toward functional or immunodomi nant domains may depend on the sequence of the infecting virus, and th e role of three frequent substitutions (asparagine by tyrosine, prolin e by serine, and serine by proline or leucine at positions 93, 192, an d 250 respectively) was established, Finally, the role of the genetic background of the host may condition the humoral immune response as in dividuals infected by HTLV-Is harboring the same predicted gp46 peptid e sequence may recognize one, several, or all regions examined.