Subfamily: Avulavirinae

Genus: Orthoavulavirus

Distinguishing features

Members of all species of the genus Orthoavulavirus share greater sequence relatedness within the genus than with members of other genera.  

Virion

See discussion under family description.  

Genome organization and replication

See discussion under family description. 

Biology

The orthoavulaviruses include significant avian pathogens, of which Newcastle disease virus (NDV), a regulatory-defined strain of avian paramyxovirus 1 (APMV-1, species Avian orthoavulavirus 1), is the most important. Many strains of NDV, both virulent and avirulent for chickens and pigeons, have been extensively analyzed. The many other antigenically related avian paramyxoviruses are not well studied. Previously species were defined by the serotypes deduced from hemagglutination-inhibition tests, with weak interactions occurring between different types.  

Species demarcation criteria

Species demarcation is now entirely based on the distance in the phylogenic tree based on the comparison of complete large (L) protein amino acid sequences. Since the primary criterion is the tree topology, whether or not a virus belongs to the same species becomes a matter of branch length between the nearest node and the tip of the branch. This length is defined as 0.03 in the trees generated as described in the legend to Figure 3. .Paramyxoviridae.