title: Detection of unusual mutation within the VP1 region of different re-isolates of poliovirus Sabin vaccine.
abstract: In the present study, a genomic analysis of full VP1 sequence region of 15 clinical re-isolates (14 healthy vaccinees and one bone marrow tumor patient) was conducted, aiming to the identification of mutations and to the assessment of their impact on virus fitness, providing also insights relevant with the natural evolution of Sabin strains. Clinical re-isolates were analyzed by RT-PCR, sequencing and computational analysis. Some re-isolates were characterized by an unusual mutational pattern in which non-synonymous mutations outnumbered the synonymous ones. Furthermore, the majority of amino-acid substitutions were located in the capsid exterior, specifically in N-Ags, near N-Ags and in the north rim of the canyon. Also mutations, which are well-known determinants of attenuation, were identified. The results of this study propose that some re-isolates are characterized by an evolutionary pattern in which non-synonymous mutations with a direct phenotypic impact on viral fitness are fixed in viral genomes, in spite of synonymous ones with no phenotypic impact on viral fitness. Results of the present retrospective characterization of Sabin clinical re-isolates, based on the full VP1 sequence, suggest that vaccine-derived viruses may make their way through narrow breaches and may evolve into transmissible pathogens even in adequately immunized populations. For this reason increased poliovirus laboratory surveillance should be permanent and full VP1 sequence analysis should be conducted even in isolates originating from healthy vaccinees.
authors.affiliation: Department of Biochemistry & Biotechnology, School of Health Sciences, University of Thessaly, Ploutonos 26 & Aiolou, 41221 Larissa, Greece.
authors.forename: Evaggelos
authors.initials: E
authors.lastname: Dedepsidis
authors.forename: Ioannis
authors.initials: I
authors.lastname: Karakasiliotis
authors.forename: Eleni
authors.initials: E
authors.lastname: Paximadi
authors.forename: Zaharoula
authors.initials: Z
authors.lastname: Kyriakopoulou
authors.forename: Dimitrios
authors.initials: D
authors.lastname: Komiotis
authors.forename: Panayotis
authors.initials: P
authors.lastname: Markoulatos
mesh_terms: D019943:Amino Acid Substitution; D001483:Base Sequence; D019046:Bone Marrow Neoplasms / Q000821:virology; D036022:Capsid Proteins / Q000737:chemistry / Q000235:genetics*; D002648:Child; D002675:Child, Preschool; D019143:Evolution, Molecular; D005260:Female; D005814:Genes, Viral; D006801:Humans; D007223:Infant; D008297:Male; D008958:Models, Molecular; D017955:Poliovirus / Q000235:genetics*; D011055:Poliovirus Vaccine, Oral / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification*; D012189:Retrospective Studies; D012703:Serotyping
chemical_list: D036022:Capsid Proteins; D011055:Poliovirus Vaccine, Oral; C442540:VP1 protein, Poliovirus