Residual DNA Testing
Residual DNA is deoxyribonucleic acid fragments derived from the host organism that may be present in recombinant biologics (e.g., recombinant DNA products, monoclonal antibodies, and vaccines) from manufacture processes. Necessity of measuring residual DNA in recombinant products is primarily based on demonstration of effective purification during manufacturing, but also on some hypothetical concerns that, depending on the host expression system, some DNA sequences may be potentially infectious or oncogenic (e.g., HIV virus gene and the Ras oncogene, respectively). On the other hand, genomic DNA from microbial sources could increase the risk of immunogenicity to the target recombinant protein being expressed, due to the high CpG content and unmethylated DNA sequence. For these and other reasons, it is necessary for manufacturers to show clearance of DNA throughout production processes and to confirm low levels in the final drug substance using an appropriately specific and quantitative analytical method.
Residual DNA Testing at Creative Animodel
Compliant with the FDA and EMA guidelines, Creative Animodel provides a comprehensive range of residual DNA testing services for our customers. Our testing platforms have acceptable performance with respect to accuracy, linearity (characterization of the assay response curve), detection limit, system suitability, and specificity. We offer the following methods to detect the species-specific target sequences from the non-specific total DNA.qPCR assay
qPCR assays are available for detection of the same species range of DNAs. The assays are performed as quantitative GLP/GMP assays and generate exact values for the mass of DNA in a sample. The assays routinely have a detection limit in the sub-picogram range, well below the mandated detection limit for residual DNA assays.Hybridization assay
For determination of host residual DNA, hybridization assays utilizing DNA probes prepared from the host cell's genomic DNA have commonly been used for products derived from bacterial expression systems to obtain the required low picogram sensitivity (Figure 1). The assays routinely have a detection limit in the 10-100 pg range, well below the mandated detection limit for residual DNA assays.
Figure 1. Principle of sandwich hybridization assay.
Threshold assay uses DNA binding-proteins with high affinity for single-stranded DNA for nonspecific quantification of total DNA. The assays routinely have a detection limit in the 10 pg range, well below the mandated detection limit for residual DNA assays.
With years of experience in the field of biosafety, Creative Animodel provides various assays to evaluate the quality and quantity of residual DNA in biological products deriving from the host organism. If you have any needs, please don’t hesitate to contact us.
1. Wang, X.; et al. Residual DNA analysis in biologics development: Review of measurement and quantitation technologies and future directions. Biotechnology & Bioengineering. 2012, 109(2):307-317.