Detection of coronavirus in calf faeces with a haemadsorption-elution-haemagglutination assay (HEHA)

A simple and rapid procedure has been developed for the detection of bovine coronaviruses in faecal specimens. The method consists of adsorption of the virus onto mouse erythrocytes at 4°C, removal of unadsorbed material and elution of adsorbed viral material at 37°C. The eluate is then used in a haemagglutination test. Specificity of the reaction is checked by a blocking assay. No non-specific reactions have been observed. The sensitivity of the test appeared to be better than that of the electron microscope, at least when crude faecal extracts are used. By ultracentrifugation of the eluates the sensitivity of the assay can be further improved.