Evaluation of Potency of Measles Vaccine used in Iran: Comparison ofWHO and NIBSC Method in Cell Culture

Measles has been a major cause of illness and death in children and vaccination against the diseaseis part ofthe who global immunization program. a suitable vaccine should create maximum immuneresponse against the pathogen and must be safe for the user. thus, after production, vaccines mustbe analyzed and controlled by the producer and confirm by relevant governmental organizations. thefood and drug control lab (fdcl), ministry of health, is the secondary control center on potencyofvaccines in iran. in this study, we have set up the who and nibsc methods in fdcl and comparethese methods on determining the potency of measles vaccine.measles vaccines were obtained from razi institute iran. nine dilutions of vaccine (10-1 to 10-5)in 0.5 log interval were mixed with vero cell suspension and seeded. in who method , the cells wereincubated at 36°c for 10 days, during which the cells were checked for cytopatic changes everyday. toset up the assay, we tested the vaccine dilution with four different cell suspensions (2x ios-5x i04/well)and four different concentration of serum (2.5-10%). based on our results, in the assays, 5% serumand ix 105 cells were used. the potency assay was performed with six different vaccines producedin one batch and the mean potency for measles was 104.32 (plus-minus) 0.24 ccidsaivial for a ten-dos e vial. innibsc method following seeding of vero cells, the medium was removed after 3 hours and overlaywas added. then the plates were incubated at 35°c for 10 days. after incubation period, the overlaywas removed, the plaque s were stained with methyl violet and counted. this assay was repeated threetimes and the mean of the results was 5.83 (plus-minus) 0.03 10glo pfu/dose.in this study, we have set up the who and nibsc methods and results indicated that the potencyof the vaccine is in acceptable range in either method. furthermore, the who method is simple andless time consuming compared to nibsc which is complicated and requires more effort to producereproducible results