The complete genome consensus sequence was determined for avian paramyxovirus (APMV) serotype 9 prototype strain PMV-9/domestic Duck/New York/22/78. The genome is 15,438 nucleotides (nt) long and encodes six non-overlapping genes in the order of 3'-N-P/V/W-M-F-HN-L-5' with intergenic regions of 0-30 nt. The genome length follows the "rule of six" and contains a 55-nt leader sequence at the 3' end and a 47-nt trailer sequence at the 5' end. The cleavage site of the F protein is I-R-E-G-R-I downward arrowF, which does not conform to the conventional cleavage site of the ubiquitous cellular protease furin. The virus required exogenous protease for in vitro replication and grew only in a few established cell lines, indicating a restricted host range. Alignment and phylogenetic analysis of the predicted amino acid sequences of APMV-9 proteins with the cognate proteins of viruses of all five genera of family Paramyxoviridae showed that APMV-9 is more closely related to APMV-1 than to other APMVs. The mean death time in embryonated chicken eggs was found to be more than 120h, indicating APMV-9 to be avirulent for chickens.