Circulation of Type 1 Vaccine-Derived Poliovirus in the Philippines in 2001

TLDR

Type 1 cVDPV was last detected in the Philippines in September 2001, prompting extensive OPV campaigns that raised population immunity in late 2001–early 2002. In 2001, highly evolved type 1 cVDPV was isolated from three AFP patients and a contact in three communities; genomic sequencing revealed capsid derived from Sabin 1 but most noncapsid from an unrelated enterovirus, with isolates closely related, sharing a recombination site, and largely indistinguishable from wild polioviruses, except the most recent isolate retained temperature sensitivity and partial attenuation.

Abstract

ABSTRACT In 2001, highly evolved type 1 circulating vaccine-derived poliovirus (cVDPV) was isolated from three acute flaccid paralysis patients and one contact from three separate communities in the Philippines. Complete genomic sequencing of these four cVDPV isolates revealed that the capsid region was derived from the Sabin 1 vaccine strain but most of the noncapsid region was derived from an unidentified enterovirus unrelated to the oral poliovirus vaccine (OPV) strains. The sequences of the cVDPV isolates were closely related to each other, and the isolates had a common recombination site. Most of the genetic and biological properties of the cVDPV isolates were indistinguishable from those of wild polioviruses. However, the most recently identified cVDPV isolate from a healthy contact retained the temperature sensitivity and partial attenuation phenotypes. The sequence relationships among the isolates and Sabin 1 suggested that cVDPV originated from an OPV dose given in 1998 to 1999 and that cVDPV circulated along a narrow chain of transmission. Type 1 cVDPV was last detected in the Philippines in September 2001, and population immunity to polio was raised by extensive OPV campaigns in late 2001 and early 2002.