Evaluation of Vitality of Sarcocysts in Beef by the Dapi Fluorescence Test

Koudela B., L. Steinhauser: Evaluation of Vitality of Sarcocysts in Beef by the DAPI Fluorescence Test. Acta vet. Brno, 53,1984: 193-197. Vitality of Sarcocystis sp. cystozoites in beef was evaluated by means of the DAPI fluorescence test. Results were verified by biological assays in definitive hosts. Sarcocysts remained vital in beef kept at refrigerator temperature over a period of 20 days after slaughter. They did not survive in frozen ( -18°C, 48 hours), cooked (70 °C, 10 min.), and pickled (12 % sol. curing mixture, 12°C, 72 hours) meat. Preliminary experiments with other protozoa indicate that the DAPI fluorescence test will meet application in different parasitological topics. Cystozoite, fresh meat, chilled meat, frozen meat, cooked meat, pickled meat. There are three species of the genus Sarcocystis known in muscle tissue of cattle. Their definitive hosts are different and so are apparently their pathogenic effects on the intermediate host: S. cruzi has the dog as definitive host and acts as pathogenic organism for cattle, S. hirsuta with the cat as definitive host is less pathogenic for the ox; S. hominis who has the man as definitive host, seems not to be pathogenic for the intermediate host. Several ways have been designed how to evaluate vitality and infectivity of sarcocysts in beef meat. Gestrich and Heydorn (1974), Fayer (1975), Golubkov (1978), and Leek and Fayer (1978) performed assays in definitive hosts. Beside biological experiments, in vitro cultivation and dye-colouring by methylen or trypan blue were recommended (Bergler et aI., 1980). Our goal was to examine the availability of the DAPI fluorescence test fot the same purpose. DAPI (4,6-diamidino-2-phenylindol) (SERVA FEINBIOCHEMICA) is a substance with soecific affinity to intracellular DNA and emits intensive fluorescence in the UV light (Russel et aI., 1975). Schilling et al. (1979) and Niemann et al. (1981) worked with the DAPI fluorescence test to determine vitality of early embryonic stages in cattle and rabbit. After incubation of embrya with DAPI, nuclei of dead cells emitted fluorescence whereas the live ones did not. Russel et al. (1975) and Hyman and MacInnes (1979) based detecting of intracellular parasites, mycoplasms and viruses on the specific activity of DAPI to DNA. Materials and Methods Meat samples From 10 at random chosen cows aged 3 to 5 years, samples of diaphragmal muscles and m. longissimus dorsi were collected at each stage of meat processing: A. Fresh meat Samples of 100-150 g were collected one hour after slaughter. B. Chilled meat As the next step in meat processing, beef halves were cooled down to 16°C in the core by a stream of cold air in a quick-chilling tunnel for 10 hours, then cut to quarters and stored in the chilling