Identification of a human endogenous LTR-like sequence using HIV-1 LTR specific primers.

Using 'consensus' primers derived from the LTR region of 15 HIV-1 isolates, a fragment of 583 bp was amplified from human DNA. Even though specificity was confirmed by Southern blot analysis with a conserved LTR oligonucleotide probe, no significant homologies were detected to either retroviral regions or human or non-human published sequences. Nevertheless, when used as a probe, the 583-bp fragment identified a unique DNA sequence in the human genome on chromosome 1, and cross-reactive sequences in monkey, but not mouse, DNA. This novel, unique and conserved sequence of 583 bp was used to isolate a human HS-1 clone in which the structural property of a viral LTR could be identified

The Nucleotide Sequence of Koala (Phascolarctos cinereus) Retrovirus: a Novel Type C Endogenous Virus Related to Gibbon Ape Leukemia Virus

A novel retrovirus, morphologically consistent with mammalian C-type retroviruses, was detected by electron microscopy in mitogen-stimulated peripheral blood mononuclear cell cultures from 163 koalas and in lymphoma tissue from 3 koalas. PCR amplified provirus from the blood and tissues of 17 wild and captive koalas, and reverse transcriptase-PCR demonstrated viral mRNA, viral genomic RNA, and reverse transcriptase activity in koala serum and cell culture supernatants. Comparison of viral sequences derived from genomic DNA and mRNA showed identity indicative of a single retroviral species—here designated koala retrovirus (KoRV). Southern blot analysis of koala tissue genomic DNA using labelled KoRV probes demonstrated banding consistent with an endogenous retrovirus. Complete and apparently truncated proviruses were detected in DNA of both clinically normal koalas and those with hematopoietic disease. KoRV-related viruses were not detected in other marsupials, and phylogenetic analysis showed that KoRV paradoxically clusters with gibbon ape leukemia virus (GALV). The strong similarity between GALV and KoRV suggests that these viruses are closely related and that recent cross-host transmission has occurred. The complete proviral DNA sequence of KoRV is reported