Health and medicine explained.

Your Health This MonthGerms that make you fat, cloned cows that won't make you sick, and the latest wonders of Botox.

By Sydney SpieselPosted Tuesday, Jan. 9, 2007, at 3:30 PM ET

This month, Dr. Sydney Spiesel discusses cattle engineered to be free of mad cow disease, a once-and-for-all flu vaccine, fattening bacteria, and Botox as a cure for writer's cramp.

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Safe beef

Disease: As my vegetarian friends delight in reminding me, Creutzfeldt-Jakob disease, which attacks and eventually destroys the brain, can be transmitted to humans who eat beef from cattle infected with bovine spongiform encephalopathy, or mad cow disease. Both BSE and Creutzfeldt-Jakob are thought to be caused by something really weird: not a virus, bacterium, or parasite, but a prion—a normal protein called PrPR whose function is unknown, and which becomes infectious when its structure changes because it has misfolded.

Question: What would happen if you used the tools of molecular biology and animal cloning to produce cattle that lack the PrPC protein? Could such an animal survive? What effect would the absence of PrPC have on it?

Answer: Drs. Yoshimi Kuroiwa and James Robl of the biotech firm Hematech and Jürgen Richt of the United States Department of Agriculture have come up with an answer: The cows seem to develop in a completely normal way, unaffected by the missing protein. More importantly, laboratory studies showed that their brain tissue did not allow for the development of prions. This makes it extremely unlikely that beef or products made from animals like these could cause Creutzfeldt-Jakob disease in humans.

Implications: This discovery could have even broader import. Hematech is trying to use biotechnology to develop cattle that produce large quantities of human antibodies directed against specific diseases. Normally, when cow or sheep or horse antibodies are used to treat or prevent human disease, our bodies soon recognize them as foreign and become allergic to or inactivate them (or both). But if cows could produce human antibodies, they would not be deemed foreign and our bodies would not reject them. It would be especially reassuring if these antibodies could be produced in prion-free cattle like the ones described by Kuroiwa and colleagues, since products from those cows couldn't pass on Creutzfeldt-Jakob disease to humans being treated with them.

Bonus: My own interest in all of this is more primitive. I'd just like to go back to eating a few beef products—cervelles au beurre noir, for instance—presently considered too risky for dinner. How perfect that the Food and Drug Administration just issued a report on the safety of cloned meat for human consumption!

A one-shot-forever flu vaccine?

Problem: I'm tired of giving flu shots, worrying about my annual vaccine supply, and (most of all) of the possibility of an avian influenza pandemic. Wouldn't it be great if we could come up with a universal vaccine—one that covered all strains of flu virus and could protect us even against new and dangerous mutations like the H5N1 bird flu?

New research: Current vaccines target structures on the surface of the flu virus, large molecules that promote attachment and penetration of the virus to the human cell. Unfortunately, these structures are the very ones that mutate so readily and for that reason make last year's vaccines useless. But there is another possible molecular target: the "M2" protein, also found of the surface of the virus, and much less likely to mutate. Walter Fiers and his research group at Ghent University in Belgium have been looking for years into a vaccine directed against M2. A recent paper by Fiers, Marina de Filette, and their co-workers describes promising results—though limited to mice—for an M2-targeting vaccine that's administered in a nicer way than usual: by nasal spray.