Abstract
Chickens were immunized with eight different serotypes of avian paramyxovirus (PMV). Ninety percent of splenic IgG antibody-forming cells (AFC) were serotype-specific with respect to the glycoprotein and nucleoprotein-polymerase antigens in an indirect immunoperoxidase binding system. The IgG AFCs which cross-reacted between serotypes divided the serotypes into two mutually exclusive super serogroups composed of PMV-1, -3, -4, -7 and -9, and PMV-2, -6 and -8. PMV-5 was not tested.