Comparative study of molecular and antigenic characterization for intratypic differentiation (ITD) of poliovirus...

This study was designed to compare the sensitivity of a Sabin vaccine strain-specific PCR assay and an enzyme-linked immunosorbent assay with polyclonal cross-absorbed antisera (PAb-E) for intratypic differentiation (ITD) of polioviruses (PVs). These were used for the definitive characterization of the strains. Poliovirus strains isolated in L20B and RD cell lines were subjected to both PCR and ELISA. Both PCR and ELISA identified 3 (13.6%) out of 22 isolates, respectively as poliovirus Sabin 1. PCR identified 4 (18.2%) out of 22 isolates as poliovirus Sabin 2 and ELISA identified 2 (9.1%) out of 22 isolates as poliovirus Sabin 2. None of the two assay identified poliovirus Sabin 3. Both PCR and ELISA identified 12 (54.5%) out of 22 isolates, respectively as wild poliovirus (WPV) 1. None of the assays identified any of the isolates as WPV 2 and 3. Only PCR assay was able to identify the mixture of two poliovirus Sabin serotypes (a mixture of Sabin 1 and 2) and two mixtures of poliovirus Sabin 2 and 3. In this study, only ELISA was able to identified two invalid results. Invalid results observed in this study are of important practical implication to the emergence of vaccine-derived poliovirus. This may have epidemic potential. Hence, the two ITD assays are of paramount importance for identification of PVs. It is therefore recommended in line with WHO guideline that at least two methods be used for the ITD of poliovirus isolates, and each method should be based on a different principle (i.e., antigenic and genetic properties).