Detection of Babesia gibsoni by reaction of phage display single chain antibodies with P50 proteins.

Babesia gibsoni (B. gibsoni) is a tick-borne hemoprotozoan parasite, which causes piroplasmosis in dogs. Diagnosis of canine babesiosis is commonly carried out using Giemsa-stained thin blood smears. However, at low levels of infection, it is difficult to detect Babesia organisms by observation of Giemsa-stained thin blood smears. We constructed a monoclonal phage display single chain antibody (scFv) against a B. gibsoni merozoite antigen, P50 protein. Intraerythrocytic B. gibsoni organisms are clearly stained using this antibody. The monoclonal scFv facilitated the detection of B. gibsoni organisms in canine blood samples.