Immunocompetent mice infected with LDVAG1Adeveloped autoantibodies against Golgi antigen as early as 6-7 days postinfection preceding anti-viral antibodies for nearly a week. The anti-Golgi antibody titres peaked between two and three weeks postinfection independent of the applied virus dose. Already one week postinfection anti-Golgi autoantibodies were prominent in IgG subclasses IgG2a and b. Spleen cells from these mice were fused with myeloma cells and the culture fluids were screened by indirect immunofluorescence for antibodies reactive with the Golgi antigen of normal cultured cells. A panel of cloned stable antibody-producing hybridomas has been obtained. Some antibodies showed broad cross-species reactivity, recognizing similar antigenic determinants in the Golgi region of mouse, rat and other mammalian cells and also in avian and piscine cells, whereas others recognized determinants in this cell compartment only in mammalian cells and one recognized Golgi antigen only in particular murine tumor cells. From 19 Golgi antibody producing hybridomas 3 secreted IgM-antibodies, 10 synthesized autoantibodies of the subclass IgG2a and 6 of IgG2b. Applied in immunoelectron microscopy mABs decorated the Golgi organelle. A considerable amount of LDVAGIA-induced hybridomas produced antibodies against conserved antigens associated with the cytoskeleton, mitochondria, and the nucleus. LDV-induced monoclonal anti-Golgi antibodies decorated the Golgi area in LDV- and mock-infected macrophages. However, cytoplasmic fluorescence characteristic for LDV-infected cells was not observed indicating that the anti-Golgi autoantibodies do not cross-react with the virus.