Persistence of Neospora caninum-specific immunoglobulin G antibodies in bovine blood and lung tissue stored at room temperature

Department of Parasitology SWEPAR, National Veterinary Institute, Uppsala, Sweden.

Blood and tissue samples obtained at necropsy from carcasses showing varying degrees of postmortem decomposition are sometimes used as sources of antibodies for serological tests, primarily in studies involving wild animals or in examination of aborted fetuses. To test the persistence of antibodies in blood and lung tissue kept at room temperature (approximately 20degreesC) for up to 48 and 118 days, respectively, serum and lung fluid from Neospora caninum-infected and uninfected cattle were tested using an indirect N. caninum immunostimulating complex enzyme-linked immunosorbent assay (ELISA). Testing of selected samples was also performed using a commercial Neospora competitive ELISA. Despite severe changes in the gross appearance of the samples, the blood collected through venipuncture from live animals remained essentially sterile, whereas the pieces of lung tissue showed a variety of bacterial and fungal growth. Nevertheless, there was no obvious reduction in antibody levels in either the blood or the tissue samples during the 2 observation periods. This study indicates that specific immunoglobulin G antibodies may be remarkably stable in sterile blood and decomposed lung tissue.