title: Molecular determinants of plaque size as an indicator of dengue virus attenuation.
abstract: The development of live viral vaccines relies on empirically derived phenotypic criteria, especially small plaque sizes, to indicate attenuation. However, while some candidate vaccines successfully translated into licensed applications, others have failed safety trials, placing vaccine development on a hit-or-miss trajectory. We examined the determinants of small plaque phenotype in two dengue virus (DENV) vaccine candidates, DENV-3 PGMK30FRhL3, which produced acute febrile illness in vaccine recipients, and DENV-2 PDK53, which has a good clinical safety profile. The reasons behind the failure of PGMK30FRhL3 during phase 1 clinical trial, despite meeting the empirically derived criteria of attenuation, have never been systematically investigated. Using in vitro, in vivo and functional genomics approaches, we examined infections by the vaccine and wild-type DENVs, in order to ascertain the different determinants of plaque size. We show that PGMK30FRhL3 produces small plaques on BHK-21 cells due to its slow in vitro growth rate. In contrast, PDK53 replicates rapidly, but is unable to evade antiviral responses that constrain its spread hence also giving rise to small plaques. Therefore, at least two different molecular mechanisms govern the plaque phenotype; determining which mechanism operates to constrain plaque size may be more informative on the safety of live-attenuated vaccines.
authors.affiliation: Duke-NUS Medical School, Singapore 169857, Singapore.
authors.forename: Kenneth Choon Meng
authors.initials: KC
authors.lastname: Goh
authors.affiliation: Duke-NUS Medical School, Singapore 169857, Singapore.
authors.forename: Choon Kit
authors.initials: CK
authors.lastname: Tang
authors.affiliation: Duke University School of Medicine, Durham, North Carolina 27710, USA.
authors.forename: Diana Catherine
authors.initials: DC
authors.lastname: Norton
authors.affiliation: Duke-NUS Medical School, Singapore 169857, Singapore.
authors.forename: Esther Shuyi
authors.initials: ES
authors.lastname: Gan
authors.affiliation: Duke-NUS Medical School, Singapore 169857, Singapore.
authors.forename: Hwee Cheng
authors.initials: HC
authors.lastname: Tan
authors.affiliation: Duke University School of Medicine, Durham, North Carolina 27710, USA.
authors.forename: Bo
authors.initials: B
authors.lastname: Sun
authors.affiliation: Duke-NUS Medical School, Singapore 169857, Singapore.
authors.forename: Ayesa
authors.initials: A
authors.lastname: Syenina
authors.affiliation: University of Bristol, Bristol BS8 1TD, UK.
authors.forename: Amjad
authors.initials: A
authors.lastname: Yousuf
authors.affiliation: Duke-NUS Medical School, Singapore 169857, Singapore.
authors.forename: Xin Mei
authors.initials: XM
authors.lastname: Ong
authors.affiliation: Duke-NUS Medical School, Singapore 169857, Singapore.
authors.forename: Uma Sangumathi
authors.initials: US
authors.lastname: Kamaraj
authors.affiliation: Duke-NUS Medical School, Singapore 169857, Singapore.
authors.forename: Yin Bun
authors.initials: YB
authors.lastname: Cheung
authors.affiliation: Duke-NUS Medical School, Singapore 169857, Singapore.
authors.forename: Duane J
authors.initials: DJ
authors.lastname: Gubler
authors.affiliation: University of Bristol, Bristol BS8 1TD, UK.
authors.forename: Andrew
authors.initials: A
authors.lastname: Davidson
authors.affiliation: Duke-NUS Medical School, Singapore 169857, Singapore.
authors.forename: Ashley Lauren
authors.initials: AL
authors.lastname: St John
authors.affiliation: Duke-NUS Medical School, Singapore 169857, Singapore.
authors.forename: October Michael
authors.initials: OM
authors.lastname: Sessions
authors.affiliation: Duke-NUS Medical School, Singapore 169857, Singapore.
authors.forename: Eng Eong
authors.initials: EE
authors.lastname: Ooi
mesh_terms: D000818:Animals; D002460:Cell Line; D006224:Cricetinae; D053059:Dengue Vaccines / Q000009:adverse effects; D003716:Dengue Virus / Q000235:genetics / Q000254:growth & development / Q000276:immunology / Q000502:physiology*; D054884:Host-Pathogen Interactions; D006801:Humans; D014613:Vaccines, Attenuated / Q000009:adverse effects; D010948:Viral Plaque Assay; D014774:Virulence
chemical_list: D053059:Dengue Vaccines; D014613:Vaccines, Attenuated