Researchers Discover How Fungus Protects Itself from Immune System

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Feb 4 2009, 10:17 AM EST

Researchers Discover How Fungus Protects Itself from Immune System

GEN News Highlights

Genetic Engineering News (press release) - New Rochelle,NY,USA

http://www.genengnews.com/news/bnitem.aspx?name=49082903

Researchers at Albert Einstein College of Medicine of Yeshiva

University have discovered how a fatal fungus evades the human

immune system and causes disease.

Cryptococcus neoformans typically gains access through the lungs and

can then spread throughout the body including the brain. Scientists

have known that the capsule surrounding the fungus is essential to

its ability to cause disease.

" But we didn't understand the mechanism responsible for capsule

growth, " says senior author, Arturo Casadevall, M.D., Ph.D. " As the

capsule grows larger, it reaches a point where immune system

scavenger cells, known as macrophages, can't swallow it. "

Investigators used dynamic light scattering and determined that the

capsule, composed of polysaccharides, grows by linking saccharides

together at its outer edge, forming giant molecules pointing in an

outward direction.

Polysaccharides are poorly understood, partly because they are

difficult to work with. " Also, scientists have tended to view

polysaccharides as boring molecules that simply grow to a specified

length, " adds Dr. Casadevall.

" But this study raises huge questions about polysaccharides, " he

continues. " For example, how does the organism assemble these

molecules, and how does it know how to make molecules that are

roughly the same length? We don't know. There appears to be a whole

dimension of cellular machinery that we never knew existed. "

The research appears in the January 27 issue of the Proceedings of

the National Academy of Sciences.