Hatching hep C hope

By Anna Lewcock

- Last updated on GMT

Related tags: Interferon

Researchers have managed to rear a flock of transgenic hens capable
of producing eggs that express remarkably high levels of a protein
used for the treatment of hepatitis C, potentially creating a
cheaper and more efficient rival to traditional bio-manufacturing
techniques.

By tweaking a proprietary region of DNA, researchers were able to dramatically increase the efficiency of protein production in the transgenic-hen based system, upping the quantity of interferon alpha-2a expressed in each egg from four milligrams to forty milligrams. Interferon alpha-2a is commonly prescribed for the treatment of hepatitis C, and is the active ingredient in Roche's Roferon A product for treatment of chronic hep C, hairy cell leukaemia and AIDS-related Kaposi's sarcoma. The company has also recently submitted a marketing authorisation application for the use of Avastin (bevacizumab) in combination with interferon for treatment of renal cell cancer. "Based on these expression levels, each egg contains enough alpha interferon to treat up to 15 patients suffering from hepatitis C for a full year,"​ said Elizabeth Elliot, senior project leader at Viragen Scotland. "Our estimates indicate [that this] could be produced at a substantial discount compared to the cost of traditional recombinant systems." ​ According to researchers at the Roslin Institute, the team expects to be able to maintain this elevated level of protein production, and perhaps even improve on it for both interferon alpha-2a and other protein drugs. With around 170m people worldwide estimated to be suffering from hep C, any means of increasing productivity or reducing costs for production of the drugs is likely to be of particular interest to pharmaceutical manufacturers. Viragen has developed its avian transgenic technology, known as the Ova System, in collaboration with the Roslin Institute in Scotland, and using a gene delivery system licensed from gene therapy firm Oxford BioMedica. The group used a gene delivery system based on viral vectors derived from the lentivirus equine infectious anaemia virus (EIAV) to insert genes for desired pharmaceutical proteins into the chicken gene for ovalbumin, which makes up 54 per cent of egg white. The project has resulted in several generations of transgenic hens, all able to produce therapeutic proteins in the whites of the eggs they lay. So far the group has reported successful expression of interferon beta 1-a and a monoclonal antibody (miR-24), as well as interferon alpha-2a. Biotech firm Viragen holds the worldwide exclusive licence to commercialise the Ova System, and has high hopes for future commercial application of the technique. Back in January, when the company first announced successful expression of interferon alpha-2a, a spokesperson told in-PharmaTechnologist.com com that the firm's efforts were geared towards commercialising the technology in collaboration with outside partners, though when this could actually happen is still a little unknown. "It really depends on what lead candidate we pick,"​ Elliot told in-PharmaTechnologist.com. "We've been trying to identify niche areas at which to angle the technology, but we anticipate being able to commercialise sooner rather than later." ​ Commercialising would obviously involve numerous flocks of hens which would be put to work laying enough eggs to satisfy the demand for the particular therapeutic proteins. Elliot explained that this bio-manufacturing could be achieved either through companies having their own flock of transgenic hens, or Viragen offering a kind of contract-laying service to commercial partners. The company is already working with a number of potential protein candidates and has high hopes for generating significant expression levels for other high-value proteins. Previous estimates, for example, have already suggested that a single flock of a few hundred birds could satisfy the entire US market demand for interferon beta-1a. The latest news is further validation of the company's egg-based protein manufacturing platform, and managing director of Viragen Scotland, Karen Jervis, sees the announcement as the potential "catalyst to establish the Ova System as the leading transgenic manufacturing system for difficult-to-manufacture proteins."

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