Retrospectively, we demonstrated that seven pigs necropsied in 1989 had cha
racteristic porcine circovirus 2 (PCV-2) lymphoid tissue lesions of severe
lymphoid depletion, syncytial giant cell formation, and intracytoplasmic in
clusion bodies in macrophages. Immunohistochemically, PCV-2 antigen was det
ected in these tissues and the distribution of positive staining correspond
ed to the distribution of inclusion bodies. Electron microscopy demonstrate
d viral particles compatible with porcine PCV-2. Therefore, the disease occ
urred in Japan as early as 1989.