Third protein successfully expressed in transgenic chicken eggs

This is the third therapeutic protein that researchers at the Roslin Institute (in collaboration with Oxford BioMedica and Viragen) have succeeded in producing in the transgenic eggs, already having reported positive results for interferon beta 1-a and a monoclonal antibody (miR-24). The results mark another step in the group's proof-of-principle study with the aim of establishing the process as an alternative to current costly bio-manufacturing processes. "The project is designed to develop the chicken into a pharmaceutical bioreactor, one that can meet the growing need for protein-based human therapeutics,"​ read a statement released by Oxford BioMedica. "This technology is being developed as an efficient and economical alternative to standard bio-manufacturing techniques, having many apparent advantages in ease of scale-up, lower costs of production and quality of product produced."​ Alpha interferon is produced by the human immune system and is crucial in disease resistance. Interferon alpha-2a, which the researchers successfully produced, is the active ingredient in Hoffman-La Roche's drug Roferon A (interferon alpha-2a, recombinant), used for the treatment of chronic hepatitis C, hairy cell leukaemia, and AIDS-related Kaposi's sarcoma. A Viragen spokesperson confirmed to In-PharmaTechnologist.com that while Roche have not been involved with the transgenic programme and are not in collaboration with the group, "a goal of [the company] is to commercialise the technology in collaboration with partners and so [the firm's] activities are geared towards this objective."​ Only a few weeks ago the collaborative group announced that they had successfully managed to breed five generations of transgenic hens, maintaining expression of therapeutic proteins in the egg whites through the generations. This was a significant step in taking the field closer to the possibility of transgenic flocks that could be used as natural bio-manufacturing plants to serve the pharmaceutical industry. The research group used viral vectors derived from the lentivirus equine infectious anaemia virus (EIAV) to insert genes for the desired pharmaceutical proteins into the chicken gene for ovalbumin, which makes up 54 per cent of egg white. Biotech firm Viragen holds the worldwide exclusive licence to commercialise the Roslin Institute's avian transgenic technology (known as OVA), and has high hopes for future commercial application of the technique: "Typically, single-subtype, recombinant alpha interferon is manufactured in bacterial or mammalian cells in bioreactors housed in complex and costly facilities,"​ said Viragen vice president Karen Jervis. "With the OVA System, we expect to offer large-scale manufacturing capabilities in a setting far less capital-intensive and with high levels of efficiency and quality."​ There is currently much investigation and research into the viability of transgenic animals and crops being used as a cheaper and more efficient way of producing a variety of drugs and treatments. Canadian firm SemBiosys last year announced that they had achieved commercial levels of the hormone insulin in their transgenic safflower plant, and researchers in Belgium also recently reported success in gaining high yields of antibody variants in the seeds of Arabidopsis​ plants. Although it is likely to be some time before the therapeutic proteins produced by the transgenic hens are tested directly on patients, Jervis is confident in the technique. "Regulatory approval will be key but this technology relies on a combination of existing technology for new end point,"​ she told In-PharmaTechnologist.com. "Hen eggs have been used for vaccine manufacture for over 30 years. Our gene delivery system is being developed for use in human gene therapy and so is designed to meet extremely stringent safety profiles. Also, recent approval of ATryn [recombinant human antithrombin] by GTC Biotherapeutics (transgenic goats) means regulators are familiar with transgenic bioproduction."​