Abstract
The hemagglutinin of A/Dk/Alb/60/76, an influenza A virus isolated from feral ducks in Canada, has no antigenic relatedness to any of the 16 reference hemagglutinin subtypes. Results of serological tests (HI [hemagglutination inhibition] and double immunodiffusion) with monospecific antisera to the hemagglutinin of this virus indicate that it represents a new avian hemagglutinin subtype. This hemagglutinin should be designated as Havo under the current system of nomenclature.