Effect of anti-immunoglobulin antibodies produced in cattle infected with Trypanosoma evansi on antigen detection ELISA.
The possibility of interference with the antigen-detection ELISA for trypanosomosis by anti-rodent IgG antibodies produced in cattle infected with Trypanosoma evansi was investigated. Two different ELISA for detection of trypanosome antigen and three different systems for anti-rodent IgG antibody detection were established. The former two were respectively polyclonal antibody-based and a combination of monoclonal and polyclonal antibody-based assays. The latter three were also adapted for detection of anti-mouse IgG, anti-rabbit IgG and anti-IgG antibodies cross-reactive with both rabbit and mouse IgGs. A total of 170 samples were collected from a dairy cattle farm where an outbreak of T. evansi infection was reported. One hundred and two cattle (59%) were found to be positive for trypanosome antigens by the polyclonal antibody-based assay and 86 (51%) were positive by the combination-based system. On the other hand, 51 (30%) and 10 (6%) of cattle had anti-rabbit and anti-mouse IgG antibodies respectively but none had antibodies cross-reactive with both IgGs. Of the 102 cattle positive for trypanosome antigens in the polyclonal antibody-based ELISA, 48 (47%) were also anti-rabbit IgG antibody positive. It is concluded that antigen detection ELISA based on a single-species immunoglobulin for capture and detection might misdiagnose T. evansi infection. Results indicate that this bias will be avoided if reagents for capture and detection are derived from different species.
National Institute of Animal Health, Bangkok, Thailand. kashiwa@mozart.inet.co.th
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Kashiwazaki
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Thammasart
D000818:Animals; D000911:Antibodies, Monoclonal; D000913:Antibodies, Protozoan / Q000097:blood*; D000953:Antigens, Protozoan / Q000276:immunology*; D002417:Cattle; D003429:Cross Reactions; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods / Q000662:veterinary*; D005189:False Positive Reactions; D007074:Immunoglobulin G / Q000097:blood; D051379:Mice; D011817:Rabbits; D013045:Species Specificity; D014345:Trypanosoma / Q000276:immunology*; D014354:Trypanosomiasis, Bovine / Q000276:immunology*
D000911:Antibodies, Monoclonal; D000913:Antibodies, Protozoan; D000953:Antigens, Protozoan; D007074:Immunoglobulin G