A highly divergent retroviral sequence in the tuatara (Sphenodon)

Vertebrate retroviruses have been classified into a number of different genera, and although many mammalian and avian examples have been characterized, less information exists about the retroviruses present within other vertebrate classes. We designed oligonucleotide primers against two highly conserved motifs within retroviral protease and reverse transcriptase genes and used them to isolate a retroviral fragment from the reptile tuatara (Sphenodon). Sequence analysis of this element, termed SpeV, demonstrated that it is substantially different from previously reported viruses, and that it cannot easily be placed into any known retroviral genus. Furthermore SpeV suggests that there may be some major differences between the retroviral populations found in reptiles and those present in mammals and birds.