Experimental infection of chimpanzees with the HBsAg-associated delta (delta) agent: an ultrastructural study.

Characteristic cytoplasmic membranous structures and intranuclear aggregates of particles similar to those reported in non-A, non-B hepatitis were observed by electron microscopy in the liver biopsies of chimpanzees inoculated with human serum, infectious for the delta agent. The ultrastructural changes were maximal during the intrahepatic production of the delta antigen, but were detected also independently of delta-Ag expression. The ultrastructural analogies provide further evidence that delta has properties distinct from HBV.