The pathogenicity of APMVs was first characterized by standard pathogenicity tests, namely the ICPI and MDT assays. We included two well-characterized strains of APMV-1, mesogenic BC and lentogenic LaSota, and compared their pathogenicity with that of APMV serotypes 2-9. This showed that APMV serotypes 2-9 were avirulent by both assays. Of types 2-9, only APMV-3 was associated with embryo death in the MTD assay and disease in the ICPI assay, although these effects were modest and APMV-3 was categorized as avirulent by the standards of these assays. By the MDT assay, the other types (types 2, 4, 5, 6, 7, 8, and 9) lacked detectable virulence and thus were less virulent than the well-known avirulent vaccine strain APMV-1 LaSota, and by the ICPI assay these APMVs were equivalent to LaSota in lacking detectable virulence. Thus, possession of a furin cleavage site and the ability to form syncytia by APMV-5 did not correlate with virulence in vivo, nor did the ability of APMV-2 to replicate to moderate titers in cell culture without the addition of trypsin.