Genetic features of polioviruses isolated in Tunisia, 1991-2006.
BACKGROUND
Genetic characterisation of polioviruses remains highly important even in countries where wild poliovirus circulation has been interrupted. Sequence data on representative wild strains from all geographical regions is required for surveillance purposes and surveillance for vaccine-related isolates with increased potential for transmissibility in humans should continue.


OBJECTIVE
To report the genetic characteristics of wild and vaccine-related polioviruses isolated in Tunisia from 1991 to 2006.


METHODS
Wild isolates were sequenced in the VP1 genomic region and compared to each other. Vaccine-related isolates were assessed for genetic recombination by PCR/RFLP and sequence analysis of the 3D region. Recombinant viruses were assessed for genetic drift in the VP1 region.


RESULTS
The VP1 sequences of the last wild isolates, all from serotype3, showed 97.7-98.7% nucleotide homology. Nineteen percent of vaccine-related isolates were vaccine/vaccine intertypic recombinants. No recombinant with non-poliovirus enteroviruses was identified. Mutational differences in the VP1 sequences of recombinant viruses ranged from 0.0% to 0.7% indicating a limited replication period.


CONCLUSIONS
This study provides sequence data on wild polioviruses from Tunisia/North Africa and shows that in countries with continuous high vaccine coverage transmission of vaccine-related polioviruses is time-limited.
Haddad-Boubaker
S
S
Laboratory of Clinical Virology, WHO Regional Reference Laboratory on Poliomyelitis and Measles, Institut Pasteur de Tunis, 13 Place Pasteur, BP 74, 1002 Tunis, Belvédère, Tunisia. sondes_hadded@yahoo.fr
Ben Yahia
A
A
Bahri
O
O
Morel
V
V
Balanant
J
J
Delpeyroux
F
F
Triki
H
H
D000818:Animals; D036022:Capsid Proteins / Q000235:genetics; D002460:Cell Line; D040961:Genetic Drift; D016679:Genome, Viral; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D011051:Poliomyelitis / Q000453:epidemiology* / Q000821:virology*; D017955:Poliovirus / Q000145:classification / Q000235:genetics / Q000302:isolation & purification; D011055:Poliovirus Vaccine, Oral; D016133:Polymerase Chain Reaction; D012150:Polymorphism, Restriction Fragment Length; D011995:Recombination, Genetic; D017422:Sequence Analysis, DNA; D014416:Tunisia / Q000453:epidemiology
D036022:Capsid Proteins; D011055:Poliovirus Vaccine, Oral; C442540:VP1 protein, Poliovirus