In Iran we last isolated imported wild poliovirus in 2000 and the immunization coverage was 100%in 2002. During 2001, there were three AFP cases with residual paralysis from which Sabin-like type 1 polioviruses were isolated in our national polio laboratory.
The complete VP1 region of the three isolates was sequenced and amino acid substitutions associated with these neurovirulent isolates were recorded.
These isolates had either 4, 2 or 1 nucleotide substitution(s) in the VP1 region, corresponding to amino acid change in the VP1 of isolate 1 of either (), (
) or (
), respectively.
Surveillance of the VAPP cases in countries where endemic transmission has recently ceased increases our understanding of the important neurovirulent mutations in vaccine-strain isolates and assists in planning the next step in the eradication program in these countries.