To maintain polio free status will require continuous vaccination programs,
as well as vigorous surveillance for the presence of poliovirus
in clinical and environmental samples. Since OPV causes adverse
reactions in vaccine recipients and can produce virulent vaccinederived
polioviruses (VDPV), immunization programs in the
post-eradication period will require the use of inactivated polio
vaccine. The disadvantage of IPV is that it does not induce the
level of mucosal immunity needed to prevent cryptic circulation
of polioviruses in communities. There is a coordinated effort to
develop a new generation of IPV that would induce better protection.
Evaluation of mucosal immunity could be accomplished
by challenging immunized individuals with OPV and monitoring
excretion of the virus in stool. Thus the ability to identify and quantify
poliovirus in stool samples is an important part of such clinical
studies. Currently, analysis of poliovirus in clinical and environmental
samples is performed by isolation of polioviruses in cell
cultures, followed by their identification and quantitation.