The HTLV-I orfl protein is recognized by serum antibodies from naturally infected humans and experimentally infected rabbits

The mechanism of T-cell transformation by human T-cell lymphotropic virus t ype I (HTLV-I), though not completely understood, appears to involve the in teractions of several viral and cellular proteins. One of these viral prote ins, p12(1), encoded by HTLV-I orfl, is a weak oncogene that binds the 16-k Da subunit of the vacuolar ATPase and interacts with the immature beta and gamma(c) chains of the IL-2 receptor. We have expressed the singly spliced om cDNA in the baculovirus system a nd used the recombinant protein as a to ol to assess the presence of antibodies in naturally or experimentally infe cted hosts In addition, rabbit antisera were raised against Various p12(1) synthetic peptides and used to identify three antigenic regions within p12( 1), one between the two putative transmembrane regions of p12(1) and two at the carboxy-terminus of the protein. Mote importantly, sera from a natural ly infected human (1 of 32) and experimentally infected rabbits (9 of 20) r ecognized the rp12(1), demonstrating orfl expression and immunogenicity in vivo. Taken together these data provide the first evidence of orfl expressi on during HTLV-I infections, (C) 2000 Academic Press.