The detection of circulating antibodies against Sarcocystis in human and bovine sera by the enzyme-linked immunosorbent assay (ELISA) technique
Tadros, W.; Hazelhoff, W.; Laarman, J.J.
Acta Leidensia 47: 53-63
1979
ISSN/ISBN: 0065-1362 PMID: 122250 Document Number: 140806
The enzyme-linked immunosorbent assay (ELISA), using antigens of Sarcocystis hirsuta and S. cernae, successfully demonstrated circulating antibodies against Sarcocystis in the sera from cattle and humans. Almost identical results were obtained for both the antigens. The sera were also tested against S. hirsuta antigen using the indirect fluorescent antibody (IFA) test. The sera from 4 grazing cows were still serologically positive with ELISA at titres of more than or equal to 1:1280 and with IFA at 1:160. 3 pre-colostrum fed calves from serologically positive cows were negative in both tests. One calf experimentally infected with 32 700 sporocysts of S. hominis (from an infected human), exhibited a rise in titre by only one dilution in both tests. The sera from the human adults (which included 2 infected with Trichinella spiralis) were positive with both ELISA and IFA at 1:40. The IFA titres of 6 infected humans were consistently higher than those from randomly selected vegetarians (1:160 to 1:640 and 1:40 to 1:80, respectively). This distinction was less apparent with ELISA. Umbilical cord sera were positive for antibodies in 2 of 2 cases with IFA and in one of 2 with ELISA. The ELISA technique was applied as a microsystem in microtitre trays, using as antigen, crude distilled water extracts of micro-isolated sarcocysts of, respectively, S. hirsuta of cattle infective to Canidae and S. cernae of the mole infective to kestrels to test 10 cattle and 16 human serum samples. The serum samples were also tested against S. hirsuta antigen in the indirect fluorescent antibody (IFA) technique. All samples with no detectable IFA titres were negative in the ELISA, whereas all samples positive in the IFA were also positive in the ELISA. Practically identical titres were elicited in the ELISA by the bovine and rodent Sarcocystis antigen. Serum samples from free grazing cows were serologically positive, with ELISA titres of more than or equal to 1:1280 and IFA titres of 1:160. Three pre-colostrum fed calves, born to serologically positive dams were negative in both tests. A young calf, experimentally infected with 32 700 sporocysts of S. hominis shed by a human excretor, showed a rise in titre by only one dilution in both tests.