Kamel Khalili, Ph.D., his colleagues found the viral genome and viral proteins T-antigen and Agnoprotein in samples of malignant epithelial tumors in the large intestine, and they postulate that viral infection may play a role in the development of these tumors.

"There is a human virus, called JC virus, which infects greater than 90 percent of the human population worldwide, usually during early childhood," said Khalili, the lead researcher.

He explained that the virus probably infects humans through the upper respiratory tract and remains in a latent stage in most people throughout their lives. He believes that the current study findings suggest that viral infection may also occur orally through contaminated food or water.

Khalili said that two events may occur after the virus is in the intestinal tract--- the viral protein T-antigen, which has oncogenic potential, is expressed, and this protein associates with beta-catenin, an important regulatory protein.

"Beta-catenin's role in colon cancer has been previously suggested," noted Khalili. "In this study, it seems T-antigen associates with beta-catenin and deregulates its function, and it's this deregulation that is causing induction of the tumors."

Khalili and the researchers used state-of-the-art laser micro-dissection to remove both cancerous and normal cells from the colon tissue and analyze them for JC virus genomic DNA.

Results from gene amplification revealed the presence of viral early genome in 22 of the 27 tumors sampled. Expression of the viral proteins T-antigen and Agnoprotein was observed in more than 50 percent of the samples.

Khalili said that the questions now facing researchers are whether or not the JC virus actually causes tumors, whether the tumors formed because of other elements and the virus helped as a cofactor, or whether something else causes the tumors and the presence of the virus is a mere coincidence.

"We're not saying every single tumor is being induced by the JC virus, because when you detect a virus in a tumor, you cannot actually say the virus causes it," Khalili cautioned. "What we are stating is that the virus can be detected in a good number of the human colon cancer tumors we sampled, and the product of the virus, the viral protein T-antigen, which has oncogenic potential, can be detected in those tumor cells."

Khalili says that the discovery of the association between JCV and tumors is important for therapeutic and treatment reasons. "We can start developing strategies and vaccines against JC virus, which will hopefully lead to the prevention of the tumors it may induce," he says.