Development And Primary Application Of A Dipstick Colloidal Dye Immunoassay For Diagnosis Of Trypanosoma Evansi Infection In Cattle

Trypanosomiasis is a protozoosis,caused by Trypanosoma evansi.Trypanosoma evansi has a wide range of hosts and is very harmful to the hosts.The infectioned of Trypanosoma evansi can result in an acute form with high mortality and a chronic form with reduced fertility,generalized loss of body condition,neuropathy and immune suppression coupled with anemia and eventually death,which have seriously affected on the development of animal husbandry.Also,a case of human infected with Trypanosoma evansi had been reported firstly from Indian,so this this disease not only resulting in immeasurable economic losses,but also has underlying risks to the human health.Currently,the clinical conventional diagnosis of trypanosomiasis has many ways,such as haematocrit centrifuge technique(HCT),card agglutination test(CATT)and ELISA,etc.,but these methods are complicated to operate,time-consuming and require special equipment,so these methods are not suitable for using in the field and large-scale clinical detection.With the development of colloidal gold technology,the new diagnosis method of immune colloidal gold rapid diagnostic test for detecting this disease was developed and in recent years a new immune marker material of dye was appeared and it showes a better choice advantages than that colloidal gold such as lower cost,easier access,better stability,longer shelf life and so on.In this study,by using colloidal dye labeled technology and immunochromatography technology we try to establish a new diagnostic method for detecting Trypanosoma evansi infection..The affinity-purified anti-Trypanosoma evansi monoclonal antibody OB6 was marked by colloidal dye.The detection zone(T line)and the control region(C line)in NC membrane were caoted by Trypanosoma evansi monoclonal TB7 or OB6 and goat anti-mouse IgG secondary antibody respectively.By a series of optimization test we have successfully established a new colloidal dye immunoassay for diagnosis of Trypanosoma evans infection.The sensitivity test showed the detection limit of VSG is 1.05?g/ml and the cross test showed it has no cross reaction with the antigens of Toxoplasma gondii,Babesia bovis,Chlamydia and Fasciola gigantica'ES.25 positive and 50 negative sera were detected by using the dipstick colloidal dye,the dipstick colloidal gold and the sandwich ELISA.The results shoued the accuracy rates were 88%,86.7%,96%respectively.The coincidence rate of dipstick colloidal dye and colloidal gold strip was 98.5%,and the rate was 91.7%between dipstick colloidal dye and the sandwich ELISA.344 clinical sera samples of bovine from Baise and Hechi in Guangxi were detected by the new method and the results showed the positive rate was 11.63%.Compared with colloidal gold test strip and sandwich ELISA,the positive coincidence rate was 90.70%and 83.33%,respectively.The results suggested that the dipstick colloidal dye is reliable,sensitive,specific method,and it also has the advantages such as simple,fast,better stability and suitable for large-scale clinical testing.The establishment of the dipstick colloidal dye has provided another new method,which has lower cost,more stability and effective,for Trypanosoma evans disease diagnosis.