Interference between avian endogenous ev/J 4.1 and exogenous ALV-J retroviral envelopes

BASE, INRA Centre de Tours, 37380 Nouzilly, France Correspondence Caroline Denesvre denesvre{at}tours.inra.fr A new family of avian retroviral endogenous sequences designated ev/J or EAV-HP has been identified recently. Here an additional avian ev/J 4.1 endogenous sequence, ev/J 4.1 Rb, is reported. ev/J 4.1 Rb has the most extensive amino acid identity ever described for an endogenous envelope protein with the ALV-J avian leukosis virus. Here, we also demonstrate that ev/J 4.1 Rb functionally pseudotypes murine leukaemia virions and leads to a complete reciprocal interference with ALV-J envelopes. This is the first demonstration of such a high level of envelope interference between endogenous and exogenous avian retroviruses. Our results provide additional clues on the co-evolution of retroviral sequences among vertebrates. The accession numbers for the sequences described are AY157601 for ev/J 4.1 Rb and AY158693 for env ALV-J INRA-7.