Comparative analysis of the performance of residual host cell DNA assays for viral vaccines produced in Vero cells

Residual host cell DNA (rcDNA) from continuous cell lines used for manufacturing of biological medicinal products has been considered as safety risk. Historically, several analytical methods have been used for rcDNA quantitation including hybridization assay, Threshold^® assay and quantitative polymerase chain reaction (qPCR). Sanofi Pasteur has a wealth of experience in the development of methods quantifying rcDNA in vaccines. Here, we compared the performance of our in-house assays for quantifying rcDNA in viral vaccines produced in Vero cells. Vero alpha-satellite sequence qPCR was compared with the hybridization and Threshold^® assays in terms of specificity, sensitivity and precision. The impact of viral inactivation with β-propiolactone (BPL) on rcDNA, within the vaccine production process, was also assessed. We demonstrate that the quantity of rcDNA measured is influenced by the analytical method used. Vero cell DNA-specific qPCR assay was shown to be robust with a large dynamic range and no matrix interference on a range of products. The qPCR assay demonstrated greater sensitivity and specificity versus the hybridization and Threshold^® methods. Vero alpha-satellite sequence qPCR is a specific and sensitive method for the assessment of the quantity of Vero rcDNA in the highly purified vaccines.