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Question
Hello,I am here to ask you something about viruses.Viruses are species specific that means they cause infections to only a particular species.But TMV is one that affect tobacco plants.But how  they cause cancer in human?

Answer
Dear Praveen,

The suspicion that some plant viruses, and in particular TMV, can infect non-plant hosts is a relatively new one.  No one is even yet sure that TMV can cause cancer in humans.  At this point, studies are pretty much at the pilot level, as this one shows:

http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0054993

Once it is determined whether or not TMV can actually persist in human (or other mammal tissues), then the next step will be to determine how it might be carcinogenic.  In general, viruses that act as carcinogens insert their DNA into the host's DNA.  If this insertion occurs in a gene locus controlling either cell proliferation (mitosis) or programmed cell death (apoptosis), then the stage is set for the complementary mutation (affecting either mitosis or apoptosis) that could result in cancer (if the host's killer cells don't destroy the mutant cell(s) in time).  TMV may work in this fashion, but no one yet knows for sure. There are other mechanisms by which viruses can promote cancer.

Hope this helps.

Dana

Evolution

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Dana Krempels

Expertise

I can answer questions about evolutionary mechanisms and theory, including genetic drift, mutation, natural selection, etc. I also can clear up misconceptions about evolution as it's sometimes talked about by those not well-versed in the subject (e.g., some politicians and many religious fundamentalists).

Experience

I have a Ph.D. in Biology, and presently teach Evolution and Biodiversity, Genetics, Botany, and Zoology at the University of Miami.

Organizations
House Rabbit Society Beta Beta Beta Biological Honor Society

Publications
Exotic DVM Magazine (veterinary journal)

Education/Credentials
B.S. in Biology B.A. in English Ph.D. in Biology

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