Poliovirus Vaccines: Molecular Biology and Immune Response

Abstract

The pathogenesis of poliomyelitis is central to understanding the effectiveness of the vaccines that are likely to eradicate the wild-type virus from the world over the next few years. Studies of the molecular biology of the Sabin live polio vaccines have so far concentrated on their virulence or attenuation for primates or transgenic mice carrying the human receptor for poliovirus where the virus is given directly into the central nervous system or parentally. The basis of attenuation or reversion of the Sabin vaccine strains has been studied by comparing the vaccine strain of each serotype with a closely related strain, either the precursor of the vaccine strain or an isolate from a vaccine-associated case of poliomyelitis. Monoclonal antibodies can recognize neutralization sites specific for vaccine rather than wild-type strains, and the most strain-specific antibodies for any serotype are directed against site 3 (Nag III), composed of sequences from VP3 and VPl. A study was conducted in 1962 to assess the ability of immune deficient hypogammaglobulinemic patients to mount an immune response to vaccines, including polio vaccine. A strain of virus with a completely stable phenotype excreted for a brief period that was still sufficient to immunize the recipient would be valuable, and there have been attempts to develop such strains, based on both classical methods and current understanding of the molecular biology of the virus.