[Diagnosis of bovine coronaviruses using mouse erythrocyte suspensions stabilized with formalin]

Bovine coronavirus isolated from calf faeces diseased with gastroenteritis and passaged to colostrum-free calves agglutinated mouse and rat erythrocytes. The agglutination reaction depended on temperature and took place only at a temperature of 4 degrees C. At a temperature of 37 degrees C the agglutinate broke down within 15 minutes. The coronavirus could be detected by the haemagglutination test in the contents of the small and large intestines and in the faeces of experimentally and naturally infected calves. The agglutination capacity of mouse erythrocytes was not affected by careful fixation of these erythrocytes with formalin and subsequent lyophilization and remained unchanged for as long as 52 weeks of storage at a temperature of 4 degrees C. It was demonstrated by a comparative examination of 182 samples of the faeces of calves suffering from diarrhoea that haemagglutination test was as sensitive as electron microscopy.