IDENTIFICATION AND CHARACTERIZATION OF AN EXTENDED TAX PROTEIN IN HUMAN T-CELL LYMPHOTROPIC VIRUS TYPE-II SUBTYPE-B ISOLATES

The tar gene sequence of human T-cell lymphotropic virus type II isola te G12 (HTLV-II(G12)) was found to encode an extended Tax protein when compared with that of HTLV-II(MoT). In vitro transcription-translatio n of the HTLV-II(G12) tar gene produced a 40-kDa Tax protein that spec ifically reacted with serum specimens from HTLV-II-infected individual s. Limited sequence analysis demonstrated that isolates with an extend ed Tax protein were all HTLV-II subtype b (HTLV-IIb). Therefore, the e xtended Tax protein appears to be a unique characteristic of most HTLV -IIb isolates and may be useful in designing immunoassays to distingui sh between HTLV-IIa and HTLV-IIb.