Molecular Anatomy Of Influenza Virus Detailed

Science Daily — Scientists at the National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), part of the National Institutes of Health in Bethesda, Md., and colleagues at the University of Virginia in Charlottesville have succeeded in imaging, in unprecedented detail, the virus that causes influenza.

The three-dimensional structure of influenza virus from electron tomography. The viruses are about 120 nanometers -- about one ten thousandth of a millimeter -- in diameter.

A team of researchers led by NIAMS' Alasdair Steven, Ph.D., working with a version of the seasonal H3N2 strain of influenza A virus, has been able to distinguish five different kinds of influenza virus particles in the same isolate (sample) and map the distribution of molecules in each of them. This breakthrough has the potential to identify particular features of highly virulent strains, and to provide insight into how antibodies inactivate the virus, and how viruses recognize susceptible cells and enter them in the act of infection.

“Being able to visualize influenza virus particles should boost our efforts to prepare for a possible pandemic flu attack,” says NIAMS Director Stephen I. Katz, M.D., Ph.D. “This work will allow us to ‘know our enemy' much better.”

One of the difficulties that has hampered structural studies of influenza virus is that no two virus particles are the same. In this fundamental respect, it differs from other viruses; poliovirus, for example, has a coat that is identical in each virus particle, allowing it to be studied by crystallography.

The research team used electron tomography (ET) to make its discovery. ET is a novel, three-dimensional imaging method based on the same principle as the well-known clinical imaging technique called computerized axial tomography, but it is performed in an electron microscope on a microminiaturized scale.

The mission of the National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), a part of the Department of Health and Human Services' National Institutes of Health, is to support research into the causes, treatment, and prevention of arthritis and musculoskeletal and skin diseases; the training of basic and clinical scientists to carry out this research; and the dissemination of information on research progress in these diseases. For more information about NIAMS, call the information Clearinghouse at (301) 495-4484 or (877) 22-NIAMS (free call) or visit the NIAMS Web site at http://www.niams.nih.gov.

The National Institutes of Health (NIH) — The Nation's Medical Research Agency — includes 27 Institutes and Centers and is a component of the U.S. Department of Health and Human Services. It is the primary federal agency for conducting and supporting basic, clinical and translational medical research, and it investigates the causes, treatments, and cures for both common and rare diseases. For more information about NIH and its programs, visit http://www.nih.gov.

Reference: Harris A, et al . Influenza virus pleiomorphy characterized by cryoelectron tomography. PNAS 2006;103(50):19123-19127.

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Gene-engineered cattle resist mad cow disease: study

WASHINGTON (Reuters) - U.S. and Japanese scientists reported on Sunday that they had used genetic engineering to produce cattle that resist mad cow disease.

They hope the cattle can be the source of herds that can provide dairy products, gelatin and other products free of the brain-destroying disease, also known as bovine spongiform encephalopathy or BSE.

Writing in the journal Nature Biotechnology, the researchers said their cattle were healthy at the age of 20 months, and sperm from the males made normal embryos that were used to impregnate cows, although it is not certain yet that they could breed normally.

The cattle lack the nervous system prions, a type of protein, that cause BSE and other related diseases such as scrapie in sheep and Creutzfeldt-Jakob disease, known as CJD, in humans, the researchers said.

"(Prion-protein-negative) cattle could be a preferred source of a wide variety of bovine-derived products that have been extensively used in biotechnology, such as milk, gelatin, collagen, serum and plasma," they wrote in their report.

Yoshimi Kuroiwa of Kirin Brewery Co. in Tokyo, Japan and colleagues made the cattle, known as knockouts because a specific gene has been "knocked" out of them, using a method they call gene targeting.

"By knocking out the prion protein gene and producing healthy calves, our team has successfully demonstrated that normal cellular prion protein is not necessary for the normal development and survival of cattle. The cows are now nearly 2 years old and are completely healthy," said James Robl of Hematech, a South Dakota subsidiary of Kirin.

"We anticipate that prion protein-free cows will be useful models to study prion disease processes in both animals and humans," Robl, an expert in cloning technology, said in a statement.

Misfolded prion proteins are blamed for BSE and other, similar brain diseases. It is known that certain genetic variations make animals more susceptible to the diseases.

BSE swept through British herds in the 1980s and people began developing an odd, early-onset form of CJD called variant CJD or vCJD a few years later. CJD normally affects one in a million people globally, usually the elderly, as it has a long incubation period.

There is no cure and it is always fatal.

As of November 2006, 200 vCJD patients were reported worldwide, including 164 patients in Britain, 21 in France, 4 in the Republic of Ireland, 3 in the United States, 2 in the Netherlands and 1 each in Canada, Italy, Japan, Portugal, Saudi Arabia and Spain.

The disease may have first started to infect cattle when they were fed improperly processed remains of sheep, possibly sheep infected with scrapie. Although people are not known to have ever caught scrapie from eating sheep, BSE can be transmitted to humans.

BSE occasionally occurs in cattle outside Britain although it is now rare.

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