[Genetic recombination in vaccine poliovirus: comparative study in strains excreted in course of vaccination by oral poliovirus vaccine and circulating strains].
OBJECTIVE
Recombination is one of the major mechanisms of evolution in poliovirus. In this work, recombination was assessed in children during vaccination with OPV and among circulating vaccine strains isolated in Tunisia during the last 15 years in order to identify a possible role of recombination in the response to the vaccine or the acquisition of an increased transmissibility.


METHODS
This study included 250 poliovirus isolates: 137 vaccine isolates, excreted by children during primary vaccination with OPV and 113 isolates obtained from acute flaccid paralytic (AFP) cases and healthy contacts. Recombination was first assessed using a double PCR-RFLP, and sequencing.


RESULTS
Nineteen per cent of recombinant strains were identified: 20% of strains excreted by vaccinees among 18% of circulating strains. The proportion of recombinant in isolates of serotype1 was very low in the two groups while the proportions of recombinants in serotypes 2 and 3 were different. In vaccinees, the frequency of recombinants in serotype3 decreased during the course of vaccination: 54% after the first dose, 32% after the second and 14% after the third dose.


CONCLUSIONS
These results suggest that recombination enhances the ability of serotype3 vaccine strains to induce an immune response. Apart from recent vaccination, it may contribute to a more effective transmissibility of vaccine strains among human population.
Haddad-Boubaker
S
S
Laboratoire de virologie clinique, laboratoire régional de référence OMS pour la poliomyélite et la rougeole, institut Pasteur de Tunis, 13, place Pasteur, BP 74, 1002 Tunis, Tunisie. sondes_hadded@yahoo.fr
Ould-Mohamed-Abdallah
M V
MV
Ben-Yahia
A
A
Triki
H
H
D000284:Administration, Oral; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D009123:Muscle Hypotonia; D010243:Paralysis / Q000453:epidemiology / Q000209:etiology / Q000821:virology; 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; D012367:RNA, Viral / Q000235:genetics*; D016865:Reassortant Viruses / Q000235:genetics* / Q000302:isolation & purification; D011995:Recombination, Genetic; D012703:Serotyping; D013045:Species Specificity; D014416:Tunisia / Q000453:epidemiology; D014556:Urine / Q000821:virology; D014611:Vaccination; D014613:Vaccines, Attenuated; D017201:Virus Shedding / Q000235:genetics
D011055:Poliovirus Vaccine, Oral; D012367:RNA, Viral; D014613:Vaccines, Attenuated