Development and qualification of a novel virus removal filter for cell culture applications

Commercial bioreactors employing mammalian cell cultures to express biologi cal or pharmaceutical products can become contaminated with adventitious vi ruses. The high expense of such a contamination can be reduced by passing a ll gases and fluids feeding the bioreactor through virus inactivation or re moval steps, which act as viral barriers around the bioreactor. A novel vir us barrier filter has been developed for removing viruses from serum-free c ell culture media. This filter removes the 20 nm minute virus of mice by >3 log reduction value (LRV), the 28 nm bacteriophage Phi X174 by >4.5 LRV, t he mycoplasma Acholeplasma laidlawii by greater than or equal to 8.8 LRV, a nd the bacteria Brevundimonas diminuta by greater than or equal to 9.2 LRV. Robust removal occurs primarily by size exclusion as demonstrated over a w ide range of feedstocks and operating conditions. The filtered media are in distinguishable from unfiltered media in growth of cells to high densities, maintenance of cell viability, and productivity in expressing protein prod uct. Insulin and transferrin show high passage through the filter. The viru s barrier filter can be autoclaved. The relatively high membrane permeabili ty enables the use of a moderate filtration area.