The emphasis of a new approach in generating systemic viralresistance is to inhibit cell-to-cell transport of the viruses, which isthe crucial point in systemic infection, according to a leading Russianbiotechnologist, Konstantin Skryabin.

Skryabin, who directs the BioEngineering Research Center at theRussian Academy of Sciences in Moscow, said that infection in theplant, in which the virus goes into one cell and replicates, doesn't doany harm to the whole plant, which survives and is healthy.

A concept has arisen in the last five years that there are viral transportfactors, some coded by the virus and some by the host cell. Mixturesof these two factors either give or do not give the chance for the virusto go through from cell to cell, and from cell to connective tissue as afirst movement to other plant regions.

There is a set of candidates now, of the supposed transport proteins,which are coded by the viruses. And a strong group of plantvirologists at the Moscow State University pioneered this research inthe world. They found a temperature-sensitive mutant of the TobaccoMosaic Virus, which nicely replicated and infected the plant cell at24 degrees Celsius, but not at 33 C.

Transgenic plants that expressed this protein acquired a very goodnormal infection at 24 C, but no detectable infection at all at 33 C.

Skryabin said, "Theirs [at Moscow State University] was the firstdemonstration that this protein is involved in cell-to-cell transport.Now we are working on it because we know several other candidatemolecules.

"If we just change something by protein engineering and make thisplant transgenic, it will stop the cell-to-cell movement of the virus.And there is also knowledge that one virus can help or stop themovement of a different virus. That's why we hope that we candevelop a general mechanism, with one structure protective for atleast five or six viruses." _ David N. Leff

(c) 1997 American Health Consultants. All rights reserved.

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