A rapid one‐step immunochromatographic test strip for rabies detection using canine serum samples

Tao, C.; Li, G.

We developed an immunochromatographic test strip using colloidal gold‐coated staphylococcal protein A (SPA) for the detection of rabies antibody in canine serum samples. The recombinantly expressed rabies virus phosphoprotein (RV‐P) and the anti‐staphylococcal protein A (anti‐SPA) polyclonal antibody were coated on the test (T) and control (C) lines on a nitrocellulose membrane, respectively. This layout is designed such that the polyclonal antibody in canine serum is captured by the colloidal gold–SPA conjugates, before the rabies antibody complex is specifically selected by the RV‐P deposited on the T line, forming a ‘sandwich’ pattern. Unbound excess colloidal SPA then proceeds to the control line where SPA specifically interacts with the anti‐SPA antibody, producing a red precipitation at the C line, indicating the validity of the strip. We tested 165 canine serum samples with the strips, and the results were compared with those obtained using ELISA. The specificity and sensitivity of ICTS were found to be 93·1 and 92·2%, respectively. As a rapid technique, not demanding expensive instrumentation, the strip offers potential in disease monitoring, especially in rabies‐endemic developing countries. SIGNIFICANCE AND IMPACT OF THE STUDY: Simple and cheap techniques to detect rabies virus or monitor immunity against it are central in maintaining epidemiological control over the disease, particularly in endemic developing countries. While many techniques meet this requirement, they are confined to this usage as they are time‐consuming and demand expensive instrumentation. Our immunochromatographic test strip can detect rabies antibody with high specificity and sensitivity; the output can be measured with naked eye. It allows safe and quick detection that will be of value in the surveillance of the immunization status of potential targets in rabies‐endemic regions and will aid disease control.