[Genetic variability of Poliovirus: typing of strains isolated in Madagascar by restriction fragment length polymorphism (RFLP) assay].

The differentiation of the vaccine or wild origin of Poliovirus at the laboratory is an important step towards the process of the poliomyelitis eradication. We report herein the results obtained from Poliovirus types 3 and 2, isolated in Madagascar in 1997 and 2002 from healthy children and cases of acute flaccid paralysis, respectively. The technique used is based on the amplification of genome (RT-PCR), followed by Restriction Fragment Length Polymorphism assay (RFLP), performed in 3 different regions of the genome. In the capsid region (VP3-VP1 and VP1-2A), RFLP analysis allowed us to differentiate without ambiguity the wild or vaccine origin of the Poliovirus type 3, and to identify Vaccine-Derived Poliovirus (VDPV) type 2. In the noncapsid region, including the RNA polymerase and 3' non coding region (3Dpol-3' NTR), the VDPV were found to be recombinant with other Enteroviruses. These results confirm that RFLP assay is a reliable tool for intratypic differentiation and to study the genetic drift and recombination of Poliovirus.