Bluetongue virus hemagglutination and its inhibition by specific sera.

Bluetongue-virus (BTV) was found to agglutinate a variety of erythrocytes including sheep-, chicken-, guinea pig- and mouse-erythrocytes. Hemagglutination was inhibited specifically with type specific serum. A temperature dependence was only found for chicken erythrocytes, which showed a hemagglutination optimum at 37 degrees C. The hemagglutination was lost upon treatment of the virus with 0.4% trypsin as well as after treatment with 0.01 M KJO4. Heating of the virus preparation to 56 degrees C resulted in the loss of the HA-activity. Gelchromatographic studies indicated that the hemagglutinating capacity is associated with the complete virion. Whereas virulent strains of BTV hemagglutinate a number of different erythrocytes the avirulent type tested produced only a slight hemagglutination with sheep red blood cells. However, specific antiserum produced with the avirulent strain yielded strong hemagglutination inhibition (HI) with the corresponding virulent strain. Treatment of sera prior to their use in the HI proved necessary to remove nonspecific inhibitors. The efficiency of KJO4 in removing nonspecific inhibitors. The efficiency of KJO4 in removing nonspecific inhibitors indicates that carbohydrates represent the major group of nonspecific inhibitors. The data represented recommended the hemagglutination inhibition tests as a new method to identify the various BTV serotypes.