New Screening Method May Identify Tumor Viruses

Statistics now show that infection contributes to over 20% of human cancers worldwide. Presently, the list of confirmed carcinogenic infectious agents is short, however studies suggest that new infectious agents yet to be identified contribute to a wide range of diseases, including cancers. A major obstacle in new pathogen discovery is whether an infectious agent isn't identified due to lack of presence or technical failure, emphasizing the need for reliable screening methods.

Conjunctival carcinomas are tumors long suspected of having a direct infectious origin, meaning direct carcinogens are present in the tumor mass with at least one genome copy per cell. In the study researchers developed a process called digital transcript subtraction (DTS), a system for subtracting known human sequences from library data sets while leaving nonhuman sequences behind for further analysis.

DTS analysis of 241,122 conjunctival carcinoma cells disclosed only 21 that didn't concur with previous sequences from human databases, indicating its ability to screen human sequence data and identify those most likely to be of viral origin.

"DTS is a simple screening method to discover novel nucleic acids," say the researchers. "It provides, for the first time, quantitative evidence against some classes of viral etiology when no viral transcripts are found, thereby reducing the uncertainty involved in new pathogen discovery."

The researchers report their findings in the October 2007 issue of the Journal of Virology.

Article: H. Feng, J.L. Taylor, P.V. Benos, R. Newton, K. Waddell, S.B. Lucas, Y. Chang, P.S. Moore. 2007. Human transcriptome subtraction by using short sequence tags to search for tumor viruses in conjunctival carcinoma. Journal of Virology, 81. 20: 11332-11340.