Shell-eating GM fungus offers low-cost process route to anti-viral drugs

Vienna – Recent incidents, such as the SARS and Swine flu epidemics, have highlighted the need for readily available antiviral drugs. One important precursor currently used for the production of Relenza, an antiviral product from GlaxoSmithKline, is N-acetylneuraminic acid (NeuNAc) – a substance which, at up to Euro2000 a gram, can be many times more expensive than gold.

Austrian researchers, however, have now developed a process to genetically modify a common fungi to enable it to produce NeuNAc from chitin. The chemical, which is currently obtained from either natural sources or synthesised, remains expensive despite significant efforts to reduce the production costs.

Chitin is found in the shells of insects, snails and cephalopods and in the cell walls of fungi. It is estimated that in the sea alone, 10 billion tonnes of chitin are formed every year - makes it a very cheap and sustainable resource for chemical synthesis.

The scientists at the Vienna University of Technology succeeded in introducing bacterial genes into the Trichoderma fungus, which is commonly found in soil, fields and trees. The fungus is noted for its abundant secretion of hydrolytic enzymes that can degrade chitin to its monomer N-acetylglucosamine (GlcNAc) and to further metabolise this product to NeuNAc.

“We knew that Trichoderma can degrade chitin - that’s what the fungus naturally does in soil”, said Astrid Mach-Aigner, a biotechnologist who led the research team at Vienna UT. “Usually, Trichoderma breaks down chitin to monomer amino sugars. Due to the new genes, two extra reaction steps are now possible - and eventually the desired pharmaceutical N-acetylneuraminic acid is produced.”

The newly developed Trichoderma line can now be cultivated in bioreactors and produces the precious acid NeuNAc from chitin, said a statement from Vienna UT, which has patented the process.