Evaluation of monoclonal antibody–based direct, rapid immunohistochemical test for rabies diagnosis

•An MAb against the nucleoprotein of RABV has been generated and dRIT has been established by using a biotinylated derivative.•The dRIT with biotinylated MAb conjugate had high specificity and sensitivity compared with the “gold standard” FAT.•Optimization of the dRIT has been emphasized. Rabies is a major public health problem in developing countries in Asia and Africa. Although a number of laboratory diagnoses can be used for rabies control, the WHO and OIE recommended gold standard for rabies diagnosis is the direct fluorescent antibody test (FAT). However, FAT is not widely used in developing countries because of deficient financial sources to procure fluorescent microscope. Recently the direct rapid immunohistochemical test (dRIT) has been developed and has a worldwide promising application, particularly in developing countries, since its result can be read by inexpensive light microscopy, in addition to be consistent with that of FAT. However, no commercial conjugated antibody is available to meet the laboratory demand. We describe here the production of a monoclonal antibody (MAb) against rabies virus (RABV) N protein and its use as a biotinylated conjugate in a dRIT. Tested against a batch of 107 brain specimens representing a wide phylogenetic diversity of RABV collected from different animal species with multiple geographical origins in China, results showed that the dRIT had 100% specificity (95% CI 0.93–1.00) and 96.49% sensitivity (95% CI 0.88–1.00) as compared with the gold standard FAT. It therefore provides a simple, economical alternative to FAT, particularly for use in rabies diagnosis in developing countries.