Related Experiment Video
Updated: Aug 15, 2026
Particle Agglutination Method for Poliovirus Identification
Published on: April 20, 2011
The standardization of infectivity titrations of poliovaccines--a WHO collaborative study
Abstract:
The reproducibility of a method for infectivity titrations of live poliovaccines using microtitre plates was investigated in a WHO collaborative study involving eight laboratories. The large variation (up to 100-fold) in estimates of infectivity observed between laboratories using their local methods of assay was reduced to no more than fourfold when a common method was used. However, expressing infectivities relative to those of the monovalent reference viruses improved the agreement between the laboratories irrespective of the titration method employed. On the basis of these results, WHO adopted the common method used in the study as its recommended method for poliovirus titrations and established the preparations studied as international reference materials for the infectivity titrations of live poliovaccines.
Insights
A collaborative study standardized poliovirus titration methods, significantly reducing inter-laboratory variation in live poliovaccine infectivity assays. This improved consistency and led to WHO adopting a common method and establishing reference materials.
Area of Science:
- Virology
- Vaccinology
- Public Health
Background:
- Infectivity titrations are crucial for live poliovaccine quality control.
- Existing local assay methods showed significant variability between laboratories.
Purpose of the Study:
- To investigate the reproducibility of a microtitre plate method for poliovirus infectivity titrations.
- To reduce variability in live poliovaccine infectivity assays across multiple laboratories.
Main Methods:
- A World Health Organization (WHO) collaborative study involving eight laboratories.
- Comparison of local assay methods versus a standardized microtitre plate method.
- Analysis of infectivity estimates relative to monovalent reference viruses.
Main Results:
- Standardizing the titration method reduced inter-laboratory variation from up to 100-fold to no more than fourfold.
- Expressing infectivity relative to reference viruses improved agreement, regardless of the titration method.
- The common method demonstrated superior reproducibility for poliovirus titrations.
Conclusions:
- WHO adopted the standardized microtitre plate method as its recommended approach for poliovirus titrations.
- The study established key international reference materials for live poliovaccine infectivity testing.
- Standardization is essential for reliable global vaccine quality assessment.
