Evaluation of a serological test system for the diagnosis of Sarcocystis cruzi infection in cattle using S. cruzi merozoite antigen.
Fifty serum samples were examined by enzyme-linked immunosorbent assay (ELISA) for antibodies directed against crude antigens isolated from cystozoites and merozoites of Sarcocystis cruzi and Sarcocystis tenella/Sarcocystis arieticanis and merozoites of Toxoplasma gondii. Of these 50 samples, 25 were from cattle originating from an area where the prevalence of S. cruzi was found to be very low (9%) and in which no cystozoites were detected, and 25 were from cattle which were found by a digestion method to be heavily infected with S. cruzi. A very high correlation was observed between the parasitological data and the results obtained from the serological assays which used antigens from either cystozoites or merozoites of S. cruzi. The assay using the antigen derived from merozoites provided the best result for discriminating infected and non-infected animals. There was some cross-reactivity between the antigen derived from cystozoites of heterologous species of Sarcocystis and S. cruzi antibodies, and some cross-reactivity between antigen of T. gondii and antibodies to S. cruzi. The reproducibility of the assays was found to be high and similar results were observed when the sera were tested on two separate occasions. The unpurified S. cruzi merozoite antigen produced in vitro is relatively accurate in discriminating positive and negative animals and may be used for diagnosis in economically important hosts such as cattle and sheep.
Savini
G
G
School of Veterinary Studies, Murdoch University, Australia.
Dunsmore
J D
JD
Robertson
I D
ID
D000818:Animals; D000913:Antibodies, Protozoan / Q000097:blood*; D000953:Antigens, Protozoan / Q000276:immunology*; D002417:Cattle; D002418:Cattle Diseases / Q000175:diagnosis*; D003429:Cross Reactions; D004797:Enzyme-Linked Immunosorbent Assay; D005188:False Negative Reactions; D015203:Reproducibility of Results; D012522:Sarcocystis / Q000276:immunology*; D012523:Sarcocystosis / Q000175:diagnosis / Q000662:veterinary*; D014122:Toxoplasma / Q000276:immunology
D000913:Antibodies, Protozoan; D000953:Antigens, Protozoan