Non-neurovirulent, genetically stable clone of poliovirus (Sabin type III vaccine strain).

A clone of poliovirus type III (TRU-3) was derived from the Sabin-3 vaccine strain by the cDNA:RNA hybrid molecular cloning method. The virus recovered was found to be considerably less neurovirulent for primates than its progenitor Sabin III vaccine strain. Upon serial passages in humans, TRU-3 did not increase its neurovirulence (unlike the Sabin strain) and maintained the base sequence of the attenuated strain in a critical part of the 5' region of the genome (unlike the Sabin strain). The substitution of TRU-3 clone for Sabin type III in oral polio vaccine could eliminate the vast majority of cases of vaccine-associated poliomyelitis.