(47c) Purification and Recovery of Infectious Virus Particles Using Osmolyte Flocculation

Authors: 
Heldt, C. L., Michigan Technological University

Over the last two centuries, vaccines have played an important role in global public health by saving millions of lives every year. The market is demanding less expensive vaccine manufacturing operations due to the extraordinary growth in vaccine manufacturing in India, China and African union countries. To curb the cost of vaccines, these countries are looking for innovative manufacturing techniques that reduce the cost of virus purification and concentration. Various methods, such as ultrafiltration, nanofiltration, and chromatographic techniques, are available for virus purification.  However, novel unit operations are needed to reduce manufacturing costs. A low cost vaccine is essential for the equitable distribution of vaccines among developing countries.

In an effect to provide a lower cost option for vaccine purification, we have developed a novel flocculation process using osmolytes, followed by microfiltration. Osmolytes are naturally occurring compounds found in the cells of many organisms, and their main function is to stabilize intracellular proteins against environmental stresses, such as high osmotic pressure.  This is accomplished by changing the water content of the cells. Osmolytes also have the advantage of being common excipients in therapeutic products; therefore removal of the flocculant before formulation is less of a concern. We have demonstrated that osmolyte flocculation is specific to an enveloped and nonenveloped virus, as compared to model proteins. We are using diafiltration for recovery and purification of model virus particles. During diafiltration, addition of flocculating agent improves the purification with successive diavolumes. The flocculated virus particles are easy to filter using a 0.1 micron filter.  To date, we have achieved >50% recovery of a non-enveloped virus and >30% recovery of an enveloped virus using 1M mannitol as the flocculating agent. We are exploring filter pore size and flocculation time to optimize the recovery and purity of infectious virus particles.  This flocculation process shows promise as a future platform approach for vaccine purification and can be applied to a wide variety of virus particles.