Specific Toxicity Testing of Residual Pertussis Toxin in Acellular Pertussis Vaccine Using Chinese Hamster Ovary Cells
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Abstract
Background: Pertussis is prevented by a combined acellular pertussis vaccine that contains Pertussis Toxoid (PTs) and Filamentous Haemagglutinin (FHA) as the main constituents. PTd is an inactivated Pertussis toxin (PT). The specific toxicity test of residual PT remaining in the vaccine must be controlled in order to meet the standard requirements to ensure the safety of vaccines. Some traditional methods were tested toxicity in mice which caused animal suffering. Therefore, the alternative CHO cell assay was developed for replacement of animal testing by In vitro assay following 3Rs concept. CHO–K1 cells had a specific response to PT. Then, the exposure of residual PT caused CHO–K1 cells morphological changes to rosette their shapes.
Objectives: To develop and use this as the alternative method for the determination of specific toxicity of PT in the combined vaccine which contains acellular pertussis by Chinese Hamster Ovary (CHO) cell assay by monitoring residual PT in finished product.
Methods: A validation method study of specific toxicity of PT in combined vaccine which contains acellular pertussis by CHO cell assay was conducted. The qualitative assay was examined in two parameters of specificity and limits of detection which was based on the international ICH guideline. One sample of tetanus toxoid, reduced diphtheria toxoid, acellular pertussis combined vaccine (Tdap) was used to study optimal conditions and examined the validity of the method.
Results: The results of validation with pertussis toxin (JNIH–5, NIBSC) were proved that the methods were specific to pertussis toxin that showed rosette-shaped clusters of CHO cells. The lowest limit of detection of pertussis toxin was 0.0015 IU/mL. One sample of Diphtheria -Tetanus - acellular Pertussis Vaccine combined vaccine was removed adjuvant and was tested by CHO cell assay. The negative presented results indicated that the vaccine sample absented residual pertussis toxin.
Conclusion: This assay was appropriate to be adapted as a standard method for specific toxicity based on residual pertussis toxin in a combined vaccine containing acellular pertussis in both local and imported vaccine products.
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References
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