Vaccine-associated cases of poliomyelitis over a 30 year period in East Germany.

A report is presented about studies on poliovirus type 3 isolates from vaccine-associated cases or contacts of cases of paralytic poliomyelitis, observed over a period of 30 years in East Germany (former GDR). In the viral isolates, some mutations were found in comparison to the Sabin vaccine type 3 strain, distributed over the whole genome. The significance of these mutations has been discussed, especially the mutation at position 472 in the 5' noncoding region found in all the isolates investigated. In five isolates, intertypic recombination between Sabin type 3 and Sabin type 1 vaccine strain occurred. Primary and secondary structures were analysed for the recombination sites.