Avian paramyxoviruses are viruses in the genusAvulavirus. Newcastle disease virus, also known as APMV-1, is a well-characterized species within the genus. Currently, avian paramyxoviruses (APMV) consist of eleven distinct known serotypes and the numbers will increase due to isolation of new unknown serotypes. The APMVs are separated into distinct serotypes using Hemagglutination assay and Neuraminidase assay. All the APMVs hemagglutinate chicken RBCs except for APMV-5 which does not hemagglutinate any species RBC making it unique among the APMVs. APMV-6 is also unique to the presence of SH gene between F and HN genes. APMV-11 has the longest genome length among the APMVs.