Determination of Residual Pichia Pastoris DNA in Recombinant Human Albumin Products by Magnetic Beads-Based Extraction Combined with Quantitative PCR Method
WANG Min-li, MA Qiu-ping, HOU Ji-feng*
National Institutes for Food and Drug Control, WHO Collaboration Center for Standardization and Evaluation of Biologicals, Beijing 100050, China
Abstract��OBJECTIVE To develop and verify a magnetic beads-based extraction combined with quantitative PCR(q-PCR)method for determination of residual host cell DNA in recombinant human albumin products expressed in Pichia pastoris. METHODS The residual Pichia pastoris host cell DNA in samples were extracted by magnetic beads-based extraction method and then determined by Taqman probe-based q-PCR. The residual DNA content was calculated according to the standard curve. The developed method was verified for accuracy and precision with different derivation albumin matrixes and concentrations, and the residual DNA of 3 batches of recombinant human albumin products expressed in Pichia pastoris were detected. RESULTS The minimum detection limit of Pichia pastoris residual DNA by the developed method was 3 fg��L-1, the linear range was 3 fg��L-1-300 pg��L-1, and the correlation coefficient(r2) was 0.998 3. The recovery rates of spiked samples in rHA matrix were 93.58%(RSD 19.6%, n=4)at 100 fg��L-1 and 215.56%(RSD 42.9%, n=4) at 10 fg��L-1, respectively. The recovery rates of spiked samples in HSA matrix were 67.09%(RSD 6.9%,n=3)at 100 fg��L-1 and 113.40%(RSD 11.1%, n=3) at 10 fg��L-1, respectively. The residual Pichia pastoris DNA contents in 3 batches of recombinant human albumin products expressed in Pichia pastoris determined by the developed method were 5.98, 4.16, 4.49 fg��L-1(n=7) respectively and not more than 1 ng per 10 g protein. CONCLUSION Magnetic beads extraction method combined with fluorescence quantitative PCR method solves the technical problem of quantitative determination of trace DNA in recombinant human albumin products with ultra-high concentration protein. The method is accurate and reproducible, and can be used for quantitative determination of DNA residue in recombinant human albumin expressed by Pichia pastoris.
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WANG Min-li, MA Qiu-ping, HOU Ji-feng. Determination of Residual Pichia Pastoris DNA in Recombinant Human Albumin Products by Magnetic Beads-Based Extraction Combined with Quantitative PCR Method. Chinese Pharmaceutical Journal, 2018, 53(10): 804-807.
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2018, Vol. 53 
