LYMPHOPROLIFERATIVE DISEASE VIRUS OF TURKEYS - SEQUENCE-ANALYSIS AND TRANSCRIPTIONAL ACTIVITY OF THE LONG TERMINAL REPEAT

The lymphoproliferative disease virus (LPDV) is the etiological agent of a lymphoproliferative disease that naturally occurs in turkeys. Recently, we have cloned the LPDV provirus and established it as a replication-competent genome devoid of a viral oncogene [Gak et al., J. Virol. 63 (1989) 2877-2880]. This report presents the nucleotide sequence of its long terminal repeat (LTR) and establishes it as a potent transcriptional element. Several features of the LPDV LTR were similar to those found in the LTRs of the avian sarcoma-leukemia viruses (ASLV) and include the primer-binding site (tRNA(Trp)), the polypurine tract, the organization of the polyadenylation signal, the complexities of the U3, R and U5 regions, as well as a potential secondary structure in U5-R. The LTR sequence diverges significantly from the ASLV LTRs, which share a common structure and have extensive sequence homology mainly in the R and U5 domains. These findings support the conclusion that LPDV represents a distinct class of avian retrovirus, evolutionarily related to the ASLV family.