Antigenic and biochemical characterization of poliovirus type 2 isolated from two cases of paralytic disease

Three isolates of poliovirus type 2 were obtained from rectal and pharyngeal swabs of two patients with paralytic poliomyelitis from Southern Italy (1981/1983). Neither one of the patients had received oral poliovirus vaccine, although a systematic vaccination campaign is conducted in the area. Neutralization tests with strain-specific antisera and analysis of the structural proteins by SDS-PAGE indicated that the three isolates were typical Sabin-like poliovirus type 2. Moreover, neutralization assays by means of a panel of well-characterized monoclonal antibodies indicated that the three isolates carried an antigenic mosaic where both wild-type and Sabin-specific epitopes were represented. The T1 fingerprints of the RNA of the three isolates diverged slightly from the standard Sabin reference map. A comparison of the oligonucleotide fingerprints of the viruses isolated from the pharynx and the feces of one patient indicated that mutations appeared as early as during replication in the intestinal tract.