RESUMEN
BACKGROUND: Five cases of poliomyelitis due to type 2 or 3 recombinant vaccine-derived polioviruses (VDPVs) were reported in the Toliara province of Madagascar in 2005. METHODS: We sequenced the genome of the VDPVs isolated from the patients and from 12 healthy children and characterized phenotypic aspects, including pathogenicity, in mice transgenic for the poliovirus receptor. RESULTS: We identified 6 highly complex mosaic recombinant lineages composed of sequences derived from different vaccine polioviruses and other species C human enteroviruses (HEV-Cs). Most had some recombinant genome features in common and contained nucleotide sequences closely related to certain cocirculating coxsackie A virus isolates. However, they differed in terms of their recombinant characteristics or nucleotide substitutions and phenotypic features. All VDPVs were neurovirulent in mice. CONCLUSIONS: This study confirms the genetic relationship between type 2 and 3 VDPVs, indicating that both types can be involved in a single outbreak of disease. Our results highlight the various ways in which a vaccine-derived poliovirus may become pathogenic in complex viral ecosystems, through frequent recombination events and mutations. Intertypic recombination between cocirculating HEV-Cs (including polioviruses) appears to be a common mechanism of genetic plasticity underlying transverse genetic variability.
Asunto(s)
Brotes de Enfermedades , Genoma Viral , Poliomielitis/epidemiología , Poliovirus/aislamiento & purificación , ARN Viral/genética , Animales , Niño , Enterovirus Humano C/inmunología , Enterovirus Humano C/patogenicidad , Femenino , Humanos , Madagascar/epidemiología , Masculino , Ratones , Fenotipo , Filogenia , Poliomielitis/inmunología , Poliomielitis/prevención & control , Poliovirus/genética , Poliovirus/patogenicidad , Vacunas contra Poliovirus/efectos adversos , Conformación Proteica , Recombinación Genética , Análisis de Secuencia de ADN , Vacunas Sintéticas/efectos adversosRESUMEN
Listeria monocytogenes is worldwide a pathogen, but the geographic distribution of clones remains largely unknown. Genotyping of 300 isolates from the 5 continents and diverse sources showed the existence of few prevalent and globally distributed clones, some of which include previously described epidemic clones. Cosmopolitan distribution indicates the need for genotyping standardization.