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Altered Hens Lay Eggs With Immune-Boosting Proteins (Update1)

By Demian McLean

Jan. 15 (Bloomberg) -- Genetically modified hens can make eggs containing a protein that's key to human immune systems, raising the possibility of lower-cost drugs to treat multiple sclerosis and cancer, according to a study in the Proceedings of the National Academy of Sciences.

While biologists have used egg whites for at least three decades to create vaccines, modifying hens to create transgenic, or human, proteins is a new approach, according to the research team including Helen Sang U.K.-based Roslin Institute.

The protein, interferon beta 1-a, is traditionally produced in stainless-steel bioreactors in a lengthy and expensive process, said Doug Calder, a spokesman for Plantation, Florida- based Viragen Inc., which has partially funded Sang's research.

The hens might eventually serve as a sort of factory for monoclonal antibody therapies, the best-known of which is Herceptin, the cancer-fighting drug from Genentech Inc., the world's second-biggest biotechnology company, said Sang. She spoke from San Diego, California.

The European Union last year approved the first animal- produced transgenic protein for use in humans. ATryn, an anti- clotting agent, is extracted from the milk of goats that have had the human antithrombin gene inserted. Framingham, Massachusetts- based GTC Biotherapeutics Inc. makes the drug.

Sang and colleagues created transgenic hens by inserting the genes for the human proteins into the hen's gene for ovalbumin, which makes up about half of egg whites.

The team discovered that the egg whites from these hens contained functional therapeutic proteins: interferon beta-1a, an antiviral drug and miR24, a monoclonal antibody with potential for treating cancer.

To contact the reporter on this story: Demian McLean in Washington at dmclean8@bloomberg.net .

Chickens have been used to produce antibodies for research for some time now. However, genetically modifying them to produce specific proteins is probably new.

By the way, I also read a news article similar to this one. However, a question that immediately occurred to me is that since the Ifn-Beta is not being produced in a mammalian cell, would it still be glycosylated? I know that bacteria producing Betaseron don't glycosylate proteins but do birds? Note that the lack of glycosylation with Ifn-Beta 1B is believed to be one of the factors which leads to its tendency to produce more neutralizing antibodies than Ifn-Beta 1A.

NHE

You are way over my small-brained head NHE. I googled some info and I believe that birds do glycosylate proteins. Maybe someone with more knowledge can answer the question better. I'm attaching an excerpt from one of the articles I read. Not sure if I'm reading it wrong, science is not my strongest subject


"A second significant contributor to aging in tissues rich in long-lived proteins is hypothesized to be the formation of irreversibly glycosylated proteins via Maillard-type reactions (Cerami 1985; Monnier 1990). The Maillard reaction, long known to food chemists, consists of the nonenzymatic attachment of reducing sugars (that is, glycosylation) to susceptible amino acid residues of proteins, which causes "browning." Cooked meat is an example of a Maillard reaction. "Browned" proteins may have differing chemical and physical traits than their unbrowned precursors, or the glycosylation itself may interfere with the active site of enzymatic proteins. In either case, glycosylated proteins would be expected to be less effective at performing the tasks they evolved to perform. Accumulation of the advanced glycosylation products may even be facilitated by oxidative reactions (Kristal and Yu 1992; Sell and Monnier 1995).

Birds should be especially prone to the formation of glycosylated proteins, because the Maillard reaction is accelerated by increasing the concentration of glucose, which is the primary reactant, or by increasing the temperature of reaction. Birds have blood glucose concentrations 2 to 4 times higher, and body temperatures 3 to 5°C warmer, than mammals (Ritchie and others 1994). Because birds apparently avoid problems due to accumulated glycosylation products for much longer than mammals, they are likely to possess some type of especially effective defenses against the accumulation of Maillard reaction products. Superior defenses against these hypothesized aging mechanisms make birds particularly valuable models for aging research in that study of the design of avian defenses may illustrate how we might improve human defenses against these processes."