Mapping of linear epitopes of the regulatory proteins of human T cell lymphotropic virus (HTLV) type II: identification of an HTLV-IIb-restricted epitope.

Epitope mapping analyses using synthetic peptides representing the RexII and TaxII proteins identified predominant seroreactivity to the carboxyl terminus of the HTLV-IIG12 TaxII protein (G12Tax 22-G12Tax24, amino acids [aa] 312-356). Moderate reactivity to only 1 RexII peptide (G12Rex9, aa 121-140) was found, while all other RexII and TaxII peptides exhibited minimal reactivity. Peptide G12Tax24 (aa 337-356) corresponded to the extended portion of the TaxII protein characteristic of HTLV-IIb viruses and appeared to represent an HTLV-IIb-restricted epitope. This study showed that this peptide can be used in immunoassays as a quick, simple serologic tool for assessing the minimal number of HTLV-IIb viruses present within specific populations, especially when genomic DNA is not available.