title: Estimation of the number of infectious measles viruses in live virus vaccines using quantitative real-time PCR.
abstract: The potency of live attenuated virus vaccines is determined by counting or titrating viable viruses in cell cultures. These classical potency tests have the drawback that they are time consuming and laborious and show a high laboratory-to-laboratory variation. In the present study we describe the development and validation of a fast method to measure the potency of measles in trivalent measles, mumps and rubella (MMR) vaccines using quantitative real-time PCR (qPCR). Vero cells were infected with serial dilutions of a trivalent vaccine or a trivalent reference with known potency. Virus was allowed to replicate and subsequently replicated virus was quantitated by qPCR using the LightCycler technology. The virus titer in vaccine samples was estimated against reference preparations using parallel line analysis. In comparison to the plaque assay, the qPCR infectivity assay was faster and less laborious, while accuracy and intermediate precision were similar.
authors.affiliation: National Institute of Public Health and the Environment (RIVM), Centre for Biological Medicines and Medical Technology, Antonie van Leeuwenhoeklaan 9, P.O. Box 1, 3720 BA Bilthoven, The Netherlands. marjolijn.schalk@rivm.nl
authors.forename: Johanna A C
authors.initials: JA
authors.lastname: Schalk
authors.forename: Christa
authors.initials: C
authors.lastname: van den Elzen
authors.forename: Hans
authors.initials: H
authors.lastname: Ovelgönne
authors.forename: Chantal
authors.initials: C
authors.lastname: Baas
authors.forename: Peter M J M
authors.initials: PM
authors.lastname: Jongen
mesh_terms: D000818:Animals; D002522:Chlorocebus aethiops; D008458:Measles Vaccine / Q000032:analysis*; D008459:Measles virus / Q000235:genetics / Q000302:isolation & purification* / Q000502:physiology; D016133:Polymerase Chain Reaction / Q000379:methods; D015203:Reproducibility of Results; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D014709:Vero Cells; D010948:Viral Plaque Assay; D014779:Virus Replication / Q000502:physiology
chemical_list: D008458:Measles Vaccine