Assessing mucosal immunity is an important part of this work.The easiest way to measure intestinal immunity is to challenge vaccinated individuals with OPV and monitor virus excretion in stool.Currently, the procedure for detection of polioviruses in clinical samples is based on titration and isolation in cell cultures,using a human rhabdomyosarcoma cell line (RD cells) and a mouse L cell line expressing poliovirus receptor (L20Bcells) (WHO, 2004; Wood and Hull, 1999),