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Impact of cell culture process changes on endogenous retrovirus expression
Author(s) -
Brorson Kurt,
de Wit Christina,
Hamilton Elizabeth,
Mustafa Mehnaz,
Swann Patrick G.,
Kiss Robert,
Taticek Ron,
Polastri Gian,
Stein Kathryn E.,
Xu Yuan
Publication year - 2002
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/bit.10366
Subject(s) - retrovirus , chinese hamster ovary cell , cell culture , cell growth , biology , endogeny , cell , microbiology and biotechnology , biochemistry , genetics
Cell culture process changes (e.g., changes in scale, medium formulation, operational conditions) and cell line changes are common during the development life cycle of a therapeutic protein. To ensure that the impact of such process changes on product quality and safety is minimal, it is standard practice to compare critical product quality and safety attributes before and after the changes. One potential concern introduced by cell culture process improvements is the possibility of increased endogenous retrovirus expression to a level above the clearance capability of the subsequent purification process. To address this, retrovirus expression was measured in scaled down and full production scaled Chinese hamster ovary (CHO) cell cultures of four monoclonal antibodies and one recombinant protein before and after process changes. Two highly sensitive, quantitative (Q)‐PCR‐based assays were used to measure endogenous retroviruses. It is shown that cell culture process changes that primarily alter media components, nutrient feed volume, seed density, cell bank source (i.e., master cell bank vs. working cell bank), and vial size, or culture scale, singly or in combination, do not impact the rate of retrovirus expression to an extent greater than the variability of the Q‐PCR assays (0.2–0.5 log 10 ). Cell culture changes that significantly alter the metabolic state of the cells and/or rates of protein expression (e.g., pH and temperature shifts, NaButyrate addition) measurably impact the rate of retrovirus synthesis (up to 2 log 10 ). The greatest degree of variation in endogenous retrovirus expression was observed between individual cell lines (up to 3 log 10 ). These data support the practice of measuring endogenous retrovirus output for each new cell line introduced into manufacturing or after process changes that significantly increase product‐specific productivity or alter the metabolic state, but suggest that reassessment of retrovirus expression after other process changes may be unnecessary. © 2002 Wiley Periodicals, Inc. Biotechnol Bioeng 80: 257–267, 2002.