Kunik, T., Department of Biochemistry and Cell Biology, State University of New York, Stony Brook, NY 11794-5215, United States, Institute of Field and Garden Crops, Agricultural Research Organization, P.O. Box 6, Bet-Dagan 50250, Israel, Department of Pharmacology, State University of New York, Stony Brook, NY 11794-8651, United States
Tzfira, T., Department of Biochemistry and Cell Biology, State University of New York, Stony Brook, NY 11794-5215, United States
Kapulnik, Y., Institute of Field and Garden Crops, Agricultural Research Organization, P.O. Box 6, Bet-Dagan 50250, Israel
Gafni, Y., Institute of Field and Garden Crops, Agricultural Research Organization, P.O. Box 6, Bet-Dagan 50250, Israel
Dingwall, C., Department of Pharmacology, State University of New York, Stony Brook, NY 11794-8651, United States, Neurosciences Research Department, SmithKline-Beecham Pharmaceuticals, Harlow, Essex, United Kingdom
Citovsky, V., Department of Biochemistry and Cell Biology, State University of New York, Stony Brook, NY 11794-5215, United States

Agrobacterium tumefaciens is a soil phytopathogen that elicits neoplastic growths on the host plant species. In nature, however, Agrobacterium also may encounter organisms belonging to other kingdoms such as insects and animals that feed on the infected plants. Can Agrobacterium, then, also infect animal cells? Here, we report that Agrobacterium attaches to and genetically transforms several types of human cells. In stably transformed HeLa cells, the integration event occurred at the right border of the tumor-inducing plasmid's transferred-DNA (T-DNA), suggesting bona fide T-DNA transfer and lending support to the notion that Agrobacterium transforms human cells by a mechanism similar to that which it uses for transformation of plants cells. Collectively, our results suggest that Agrobacterium can transport its T-DNA to human cells and integrate it into their genome.