Development and evaluation of a rapid neutralizing antibody test for rabies

The level of virus-neutralizing antibody, which plays a crucial role in the prevention of rabies, is determined by rabies virus (RABV) neutralizing test, which are time- and cost-consuming. In order to determine the level of neutralizing antibody in vaccinees, an easy and reliable method is needed. Based on the principle of immunochromatography, we developed a RAPINA (RAPId Neutralizing Antibody) test to determine the presence of neutralizing antibody in serum. In the RAPINA test, if neutralizing antibody equivalent to 0.5 IU/ml of serum sample are mixed with an optimal amount of inactivated RABV (iRABV) and are completely absorbed by the virus, none of the iRABV can bind with monoclonal antibody that recognizes the iRABV glycoprotein (G) on the test strip. A total of 115 human sera samples were tested. The sensitivity, specificity and accuracy of the RAPINA test compared with rapid fluorescent focus inhibition test (RFFIT) as a standard test, were 88.7, 91.9 and 90.4%, respectively. The RAPINA test is a simple, safe and rapid method, which can be a substitute for neutralizing tests that use live viruses, cultured cells and fluorescence microscopy. This test might be useful for screening a large number of sera.