We have studied the reactions of hamster embryo cells transformed by ultraviolet-inactivated herpes simplex type 2 (333-8-9 T cells) to infections with adeno-associated satellite virus (AAV) and its adenovirus helpers. Resident HSV structural antigens were not detectable in early or late passage of 333-8-9 T cells. AAV structural antigens were not detected in these cells unless the cells were coinfected with a helper adenovirus. In early passage 333-8-9 T cells were permissive to infections with simian adenovirus SV15 whereas normal hamster cell line LSH was nonpermissive. In some late passages of 333-8-9 T cells infections with SV15 adenovirus led to the production of viruslike particles whose morphology was identical with reoviruses.