Establishment of a standard seed lot system of an Iranian Mumps virus strain; RS-12, for mass production of mumps and MMR vaccines.

BACKGROUND: At present the mumps virus strain used for production of mumps vaccine for our local use is Hoshino strain. However, according to our National public health policies, this strain should be replaced with a safer strain. Based on our previous data, the Iranian mumps strain; RS-12 has been proved to be the most suitable alternative to Hoshino strain with little or no adverse events following vaccination METHODS: The aim of the present study was to optimize propagation of RS-12 strain and prepare standard seeds for vaccine mass production. The virus was inoculated to cells using different methods and different multiplicity of infection (MOI). The viral suspensions were harvested using different methods. Quality control tests were run at different stages. RESULTS: Maximum viral yield was achieved when cell suspensions were inoculated at MOI of 1:10 and incubated at 36-37ºC for 48 hours, followed by replacement of the media and incubation at 33-34 ºC for 5-7 days. Filtration did not affect the viral titre. A standard seed lot system was successfully established and experimental batches of MMR vaccines were produced. CONCLUSION: The established seed lot system has met all requirements of WHO regulations and could be used in mass production of safe and efficacious mumps and MMR vaccines. Clinical trials are in progress for this newly produced vaccine.

Microtitration of rubella virus in monovalent vaccinal products.

BACKGROUND: Potency test for control of rubella vaccine is a significant factor to qualify production line and vaccination program. For this reason, WHO recommends to use the microtitration method by both vaccine companies and control laboratories. Then the study was done to improve this test. METHODS: Three rubella virus samples, including an in-house standard, a lot of vaccine and an in-process product, were tittered in cell culture tubes. Then micro titration steps were tested on 96-well microplate using cocultivation of standard rubella vaccine dilutions and RK-13 cell line. After 6-7 days, final reading was done and calculated the titer. Two other samples were assayed with the micromethod. RESULTS: Titer reduction less than 0.5 log was acquired for each sample during frequent tests and between two methods. CONCLUSION: The procedure was profitable and accurate for potency and identity tests of rubella virus vaccine, on the basis of WHO recommendations.