Click below to go to the

Vitaly Citovsky, Ph.D.

webpage at the
State University of New York,
Stony Brook.
His research into Agrobacterium is posted there.




"Tumor-Causing Plant Bacteria May Infect Human Cells"

Reuters Health News - January 31, 2001
- Emma Patten

NEW YORK - A soil bacterium that causes lumpy tumors on plants may be able to 'jump kingdoms' and insert its tumor-causing DNA into human cells, new research findings suggest. The bacterium, called Agrobacterium tumefaciens, contains a small piece of DNA that can insert itself into the DNA of a host cell and initiate a tumor. Agrobacterium is already known to cause plant tumors, but researchers wanted to test whether the bacterium could similarly insert its DNA into human cells.

Dr. Vitaly Citovsky from the State University of New York, Stony Brook, and colleagues found that the plant bacterium was able to attach to human cells and insert its DNA into human cells just as it does with plant cells. Whether Agrobacterium is dangerous to humans is unclear, however. "Here (insertion of DNA into) human cells has been observed in laboratory conditions; whether it may be relevant biologically in nature remains unknown," the researchers note in the current early edition of the Proceedings of the National Academy of Sciences.

"Our experiments were done under laboratory conditions," Citovsky told Reuters Health. "In nature, I do not believe Agrobacterium represents a danger. However, for people who work with large concentrations of this bacterium, for example researchers or certain agricultural workers who deal with heavily infected plants, it may be prudent to be careful or at least aware,'' he said.

One implication of this study, said Citovsky, is the potential for genetic flow between bacteria and animals. Another implication is that the basic biochemical and cellular reactions involved in the Agrobacterium-plant cell interaction probably exist in the animal kingdom as well.

"Presently, it appears that Agrobacterium is the only example of trans-kingdom DNA transfer," Citovsky said. "I do not rule out other possibilities but there are no data. Of course, what can be done once, can almost always be done again," he added.


From The Institute of Science in Society

Until quite recently, the genetic engineering community has assumed that Agrobacterium does not infect animal cells, and certainly would not transfer genes into them. But this has been proved wrong.

A paper published earlier this year reports that T-DNA can be transferred to the chromosomes of human cancer cells [1]. In fact, Agrobacterium attaches to and genetically transforms several types of human cells. The researchers found that in stably transformed HeLa cells, the integration event occurred at the right border of the Ti plasmid's T-DNA, exactly as would happen when it is being transferred into a plant cell genome. This suggests that Agrobacterium transforms human cells by a mechanism similar to that which it uses for transformation of plants cells.