ALVE6 integration site showing 2 putative open reading frames. ALVE6 pol is truncated at the 5′ end but encodes the reverse transcriptase (RT) thumb domain, intact RNaseH (RH), and integrase (INT) domains. The envelope ORF is complete and features a mutated recognition site for the known inhibitory miRNA miR-155 (vertical bar). Abbreviations: ALVE, avian leukosis virus subgroup E; LTR, long terminal repeat; ORF, open reading frame; SU, surface; TM, transmembrane.