“…These can be differentiated by nucleotide sequence analysis (Juhasz & Easton, 1994) and using monoclonal antibodies (mAbs) (Collins et al, 1993;Cook et al, 1993b). However, the emergence of a different APV type in the US, designated type C, has changed the situation, and this virus is believed to belong to a third subtype, if not a new serotype (Seal, 1998;Cook et al, 1999). Furthermore, the recent report from France of the existence of APV strains genetically distinct from subtypes A, B and C , referred to as type D, further complicates the situation.…”