RESUMEN
A type 2 vaccine-derived poliovirus (VDPV), differing from the Sabin 2 strain at 8.6% (78/903) of VP1 nucleotide positions, was isolated from seawater collected from a seaport in São Paulo State, Brazil. The P1/capsid region is related to the Sabin 2 strain, but sequences within the 5'-untranslated region and downstream of the P1 region were derived from recombination with other members of Human Enterovirus Species C (HEV-C). The two known attenuating mutations had reverted to wild-type (A481G in the 5'-UTR and Ile143Thr in VP1). The VDPV isolate had lost the temperature sensitive phenotype and had accumulated amino acid substitutions in neutralizing antigenic (NAg) sites 3a and 3b. The date of the initiating OPV dose, estimated from the number of synonymous substitutions in the capsid region, was approximately 8.5 years before seawater sampling, a finding consistent with a long time of virus replication and possible transmission among several individuals. Although no closely related type 2 VDPVs were detected in Brazil or elsewhere, this VDPV was found in an area with a mobile population, where conditions may favor both viral infection and spread. Environmental surveillance serves as an important tool for sensitive and early detection of circulating poliovirus in the final stages of global polio eradication.
Asunto(s)
Poliovirus/metabolismo , Agua de Mar/virología , Regiones no Traducidas 5' , Secuencia de Aminoácidos , Sustitución de Aminoácidos , Anticuerpos Antivirales/inmunología , Brasil , Proteínas de la Cápside/genética , Proteínas de la Cápside/metabolismo , Línea Celular , Humanos , Datos de Secuencia Molecular , Fenotipo , Filogenia , Poliovirus/clasificación , Poliovirus/aislamiento & purificación , Regiones Promotoras Genéticas , Reacción en Cadena en Tiempo Real de la Polimerasa , Recombinación Genética , Alineación de Secuencia , TemperaturaRESUMEN
An outbreak of paralytic poliomyelitis occurred in the Dominican Republic (13 confirmed cases) and Haiti (8 confirmed cases, including 2 fatal cases) during 2000-2001. All but one of the patients were either unvaccinated or incompletely vaccinated children, and cases occurred in communities with very low (7 to 40%) rates of coverage with oral poliovirus vaccine (OPV). The outbreak was associated with the circulation of a derivative of the type 1 OPV strain, probably originating from a single OPV dose given in 1998-1999. The vaccine-derived poliovirus associated with the outbreak had biological properties indistinguishable from those of wild poliovirus.