Protein expression systems are notoriously difficult to work with, but a bevy of researchers have found solutions that have facilitated their protein therapeutic work.
At ISBiotech’s meeting held earlier this month, speakers shared their success stories.
Penny L. Post, Ph.D., vp, regulatory affairs, Protein Sciences, and her colleagues have designed a process that involves culturing insect cells in a bioreactor, infecting the cells with a baculovirus vector engineered to contain the gene of interest, incubating the infection for the appropriate amount of time, and purifying and formulating the expressed product.
“Using this system, we recently received FDA approval for the first recombinant trivalent hemagglutinin (rHA) influenza vaccine,” shared Dr. Post. “The vaccine is cloned from FDA-selected vaccine strains. One important feature of the system is that we have eliminated the need to handle live influenza viruses. Since the manufacturing expression system does not require eggs or actual influenza viruses, no adaptation of the influenza virus is required and an exact genetic match to the viral hemagglutinin can be produced.
“This is advantageous for pandemic preparedness, as an inherently safe system for the production of vaccines for pandemic influenza and for enhancing production speed and vaccine availability.”
Dr. Post noted that the baculovirus vector insertion is being changed, and not the cell line. Therefore, a single qualified cell line and a single master baculovirus bank can be used for all products, allowing for rapid start-up of new products and faster regulatory approval.
“The system has the ability to express high levels of protein, and multiple genes may be co-expressed. The technology may be used for the production of a broad range of protein-based vaccines for both human and veterinary use,” she added.
The production bioreactor is loaded with cells from the working cell bank and then infected with the working baculovirus bank containing the gene(s) to be expressed. After 48 to 72 hours, the bioreactor is harvested, and product is purified with a series of chromatography and filtration steps, formulated into the final buffer, and filtered through a 0.2 µm filter. The product is then compounded, undergoes final filtration, and is filled into vials.