Comparison of the immune response of the rabbit to virulent and attenuated strains of type 1 poliovirus.

Rabbits were immunized with the attenuated LSc, 2a(1)b or the virulent Mahoney strain of type 1 poliovirus, or with a partially purified preparation of the latter. It was found that the animals responded in a heterogeneous manner to antigens with a homogeneous virion population, such as LSc,2a(1)b and, to a lesser extent, the partially purified Mahoney antigen. This heterogeneous immune response permits the preparation of specific antisera for intratypic serodifferentiation tests. However, the unpurified Mahoney strain, which has a heterogeneous virion population, induced a homogeneous immune response; all the antisera had a wide spectrum of antibodies and could not distinguish the wild from the attenuated strain. The differentiation capacity of the specific antisera was found to be linked to either the IgM or the IgG. The possible implications of these findings for human vaccination against poliomyelitis are discussed.