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Improvement in potency assay of measles-mumps-rubella trivalent vaccine: interference between components and measures
1Department of Measles Virus, National Institute of Health, Tokyo, Japan.
Abstract:
In the potency assay of trivalent measles-mumps-rubella (MMR) vaccine by the immunocytochemical focus assay reported previously (Fukuda et al., 1987), development of rubella foci in RK13 cells was inhibited in the presence of a large excess of mumps component, resulting in an underestimation of the titre of the rubella component. When RK13 cells are infected with the mixture of mumps and rubella viruses, mumps virus interfered with the growth of rubella virus. Interference was mediated most likely by interferon induced by mumps virus. The interference was eliminated by a partial neutralization of mumps component by the addition of anti-mumps serum to the inoculum to RK13 cells. Improved method of potency assay of MMR vaccine incorporating the above measures and other modifications are described.
Insights
A new method improves measles-mumps-rubella (MMR) vaccine potency testing. Mumps virus interference with rubella virus growth was overcome, preventing underestimation of the rubella component in the vaccine.
Area of Science:
- Virology
- Vaccine Development
- Immunology
Background:
- The immunocytochemical focus assay for measles-mumps-rubella (MMR) vaccine potency previously underestimated the rubella component.
- This underestimation occurred due to mumps virus interfering with rubella virus growth in RK13 cells.
- Mumps virus-induced interferon likely mediated this interference.
Purpose of the Study:
- To address the underestimation of the rubella component in MMR vaccine potency assays.
- To develop an improved method for accurately assessing the potency of the rubella component in trivalent MMR vaccines.
Main Methods:
- Investigated the interference of mumps virus with rubella virus growth in RK13 cells.
- Determined that mumps virus-induced interferon was the likely mediator of interference.
- Developed a method to eliminate interference by partially neutralizing the mumps component with anti-mumps serum.
Main Results:
- Mumps virus significantly inhibited rubella foci development in RK13 cells when present in excess.
- Addition of anti-mumps serum to the inoculum neutralized the mumps component, eliminating interference.
- This neutralization allowed for accurate titration of the rubella component.
Conclusions:
- Mumps virus interference is a significant issue in MMR vaccine potency assays using the immunocytochemical focus assay.
- Partial neutralization of the mumps component with anti-mumps serum effectively resolves this interference.
- An improved potency assay method for MMR vaccines has been developed, ensuring accurate measurement of all components.