MicrobiologyBytes: Escherichia coli, New Drugs, Nanotechnology and Mad Cows
The dark side of E. coli:
A news article in the latest issue of Nature (Nature 445, 8-9, 4 January 2007, subscription) asks the question, “How can we prevent more food poisoning outbreaks?” Repeated food-poisoning outbreaks in North America caused by Escherichia coli O157:H7 infected nearly 200 people and killed three. The bacterium is difficult to detect and virtually impossible to treat or eradicate. There are thousands of different strains of E. coli, most of which are harmless. But the O157 strain can make a potent toxin and latch onto intestinal cells, giving it the ability to cause kidney failure and even death. The bacteria live harmlessly in the large intestine of cows and are thought to be ubiquitous in cattle lots. Bacteria shed in faeces contaminate meat in slaughterhouses or find their way onto vegetables grown near animals or irrigated with water contaminated with manure. At a meeting earlier this year on pathogenic E. coli, a new vaccine containing proteins from O157 was described which cut the number of cows shedding bacteria by 60–70%. Canadian company Bioniche Life Sciences, has submitted the vaccine for regulatory approval in Canada, and plans to do so in the United States. Other groups are turning to bacteriophages to attack the O157 strain. Feeding sheep a mixture of bacteriophages cuts the number of pathogenic bacteria in their guts by over 1,000 times.
New drugs for hepatitis C virus and HIV:
Around 200 million people worldwide suffer from the fatal liver disease caused by hepatitis C virus, but only 30 million receive the expensive interferon-alpha that can cure them. The problem is the price: in the UK, the drug costs £7000 per patient per year.
Now scientists are planning to outmanoeuvre patents held by drug company giants Hoffman-La Roche and Schering Plough on a new form of interferon which is linked to a bulky molecule called polyethylene glycol (PEG), which makes the volatile drug last longer in the body.
And clinical trials of a new AIDS drug also show ‘phenomenal’ results. MK-0518, an HIV-integrase inhibitor, showed that when combined with two existing drugs, it reduced the virus to undetectable levels in nearly 100 percent of HIV patients prescribed a drug regimen for the first time. It had a similar effect in 72 percent of salvage therapy patients, who take a mixture of existing medications aimed at stalling the virus until new drugs appear. The U.S. Food and Drug Administration should approve MK-0518 in mid-2007, but Merck is making it available sooner to patients on a compassionate basis.
Abuse of Nanotechnology:
A new handheld germ zapper is being touted as using “nanotechnology to nix parasites”. Looking like a flip-phone (another whizzy marketing idea?), the handheld gizmo reportedly eradicates:
99.99-percent of E-Coli, staphylococcus, salmonella, and germs that cause the flu and the common cold.
Ooh, don’t all those name errors just give you more confidence in the snake-oil salesmen pushing this thing? The device allegedly uses:
UV-C light and nanotechnology to disinfect workplace keyboards or telephones (or mice), as well as items in the home that sustain germ vitality such as toothbrushes and cutting boards.
Ho ho ho. So tell me again, where’s the nanotechnology?
Prion protein negative cattle resistant to mad cow disease:
Production of cattle lacking prion protein. Nature Biotechnology, 31 December 2006:
Prion diseases are caused by propagation of misfolded forms of the normal cellular prion protein PrPC, such as PrPBSE in bovine spongiform encephalopathy (BSE) in cattle and PrPCJD in Creutzfeldt-Jakob disease (CJD) in humans. Disruption of PrPC expression in mice, a species that does not naturally contract prion diseases, results in no apparent developmental abnormalities. However, the impact of ablating PrPC function in natural host species of prion diseases is unknown. Here we report the generation and characterization of PrPC-deficient cattle produced by a sequential gene-targeting system. At over 20 months of age, the cattle are clinically, physiologically, histopathologically, immunologically and reproductively normal. Brain tissue homogenates are resistant to prion propagation in vitro as assessed by protein misfolding cyclic amplification. PrPC-deficient cattle may be a useful model for prion research and could provide industrial bovine products free of prion proteins.
