ABSTRACT
Avian plague virus was used as antigen in a counterimmunoelectrophoresis technique. This virus was selected because it detects only type-specific influenza A antibodies in human sera, avoiding the possible interference of other antigens with anodic migration. The results with reference sera, as well as the correlation of positive sera found by counterimmunoelectrophoresis and complement fixation with the proposed antigen, in the absence of other types of antibodies to fowl plague virus antigen, support the conclusion that the counterimmunoelectrophoresis technique reveals type-specific antibodies. The test is more sensitive than immunodiffusion but less sensitive than complement fixation. Its sensitivity, simplicity, and rapidity make it suitable for serologic surveys of human influenza A.