Mycoplasma toxins? One strain or more?

[Guest guest]

Perhaps curious:

Scientists have long puzzled over how an oddly shaped bacterium

called mycoplasma pneumoniae is able to cause a wide variety of

respiratory illnesses, including pneumonia, bronchitis and asthma

flare-ups.

Now, after three decades of work, San microbiologist

Baseman says he has an answer: Once inside the body, the bug produces

a toxin that injures the delicate cells of the respiratory tract.

Experts are touting the discovery as a major breakthrough that could

lead to the development of vaccines, diagnostic tests and therapeutic

medications.

" This is earthshaking, " said ph Tully, retired chief mycoplasma

investigator at the National Institutes of Health. " It answers a lot

of questions about a whole battery of these things. "

Mycoplasmas are a form of bacterium and the smallest organisms

without cell walls, which enables them to fuse with cells and disrupt

their functions.

A number of mycoplasma species are known to cause diseases in humans

and aggravate chronic conditions. One form has been linked to pelvic

diseases, and another is suspected of contributing to the onset of

illness in people with HIV infections.

Mycoplasma pneumoniae is one of the most common respiratory disease

agents. It is the culprit in community-acquired pneumonia, a stubborn

form of the illness that spreads easily in communal living

situations, such as military barracks and jails. It also has been

linked to other respiratory ailments such as asthma and has been

implicated in joint, liver and cardiac syndromes.

Scientists have struggled for years to understand how all mycoplasmas

become virulent.

" It's been baffling for all of us who have been working in this

field, plus all the people who work in infectious disease, " said

Baseman, chairman of microbiology and immunology at the University of

Texas Health Science Center.

Baseman said his team " went fishing, " using an abundant lung protein

to see what molecule from the mycoplasma would grab the hook. The

technique worked - identifying a key protein in the mycoplasma that

enabled the organism to attach to the lung protein.

" We fished out one specific protein and it turned out to be this

toxin, " Baseman said.

The toxic protein attacks in two ways, he said. It cuts a cell

molecule called NAD into two pieces and acts to damage the cell

membrane. Both actions can kill a cell, Baseman said.

The study was published Monday on the Web site of the journal

Proceedings of the National Academy of Sciences.

Understanding this chemical activity opens up a range of future

studies, said Dr. R. Doug Hardy, an assistant professor at the

University of Texas Southwestern Medical School in Dallas.

" By discovering this toxic protein, it is possible that we will be

able to make vaccines to protect people from it, which is very

exciting, " Hardy said. " We'll also be able to develop better

diagnostic tests to look for infections. "

Tully, the retired mycoplasma investigator, said other scientists who

study mycoplasmas will now revisit their work to look for similar

toxin production in other species of the bug.

" Everybody is going to have to go back 20 years and look at all these

other organisms that we know can produce mild diseases in humans and

whether that is associated with a toxin, " Tully said.

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SA scientist finds how bug hurts cells

Tumiel, Express-News Staff Writer

San Express - San ,TX,USA - April 11, 2006

http://www.mysanantonio.com/news/metro/stories/MYSA041106.01B.mycoplas

ma.d4b8458.html

ctumiel@...

Portions © 2006 KENS 5 and the San Express-News. All rights

reserved.

LINK:

Journal Proceedings of the National Academy of Sciences

http://www.pnas.org/

Best regards,

Dr. Schaller