Cytoplasmic inclusions in cells infected with the virus of equine infectious anemia (EIAV).

After infection with equine infectious anemia virus (EIAV) equine dermal (ED) cells revealed fluorescent spots in their cytoplasm which were detected with an indirect immunofluorescence technique. To characterize the nature of these cytoplasmic inclusions, comparative light and electron microscopic studies were performed. The cytoplasmic location of the spots observed in the indirect immunofluorescence assay coincided with the location of structures detected with the electron microscope. In ultrahistological studies, these spots were shown to be composed of smaller subunits which were ring-like, crescent shaped or oblong. They were always located in proximity to the endoplasmic reticulum. Cytochemical and ultracytochemical studies indicated the presence of RNA in these inclusions. EIAV-antigen was demonstrated in these cytoplasmic structures by immunoperoxidase labeling and subsequent examination by light and electron microscopy. A possible relationship of these EIAV-inclusions to the synthesis of viral particles is suggested.