( nts whose prostates had been surgically...)'Virus chip' detects new virus in prostate tumors

The researchers don't know if the virus is unique to prostate tumors because this is the first tumor type they have studied using virus chip technology. As with most scientific discoveries, the identification of this virus in human prostate tissue prompts many more questions than it answers, they emphasize.

"A hit on the array is not the end of the project; it's the beginning," Ganem says. "Pathogen discovery is really hard work." The team intends to carry out epidemiology studies to determine how widespread the virus is, how it is transmitted, and whether it causes any of the prostate tumors, or any other disease.

The gene-hunting technique DeRisi and Ganem call the Virochip is designed to identify any virus sample by comparing its DNA or RNA to more than 20,000 snippets of genetic material derived from all known viruses -- found in humans, animals, plants, fungi and bacteria. The chip draws on computer chip technology, computation and bioinformatics, but in essence it is a simple 3 x 1 inch glass microscope slide. Onto the slide the scientists robotically deposit 10 to 12 different DNA sequences from all known viruses.

Each sample appears as a microscopic dot, about a tenth of a millimeter in diameter –giving it the name micoroarray. Researchers then wash fluorescently tagged DNA from a sample of interest over the slide, and wherever the two sets of nucleic acid match up, they anneal to each other. The slide is then rinsed and visualized with a scanning laser microscope. The dots that have found a match glow with fluorescent light.