Thursday, August 19, 2010

virus behind cancer, ms?

The Scientist | After uncovering HPV's role in cancer, Harald zur Hausen is investigating another virus-disease relationship. Nobel Laureate Harald zur Hausen has a hunch, and he's gathering the data to support it.

For the past decade, zur Hausen and Ethel-Michelle de Villiers, his scientific partner and wife, are studying a little-known, single-stranded DNA virus -- Torque teno virus (TTV). Preliminary evidence is suggesting it may be an indirect cause or co-factor in certain multi-factorial diseases, including cancer and autoimmune diseases.

Addressing 675 young scientists at last month's 60th Meeting of the Nobel Laureates in Lindau, Germany, zur Hausen presented new findings on TTV. He and de Villiers have identified viral proteins that resemble certain MS auto-antigens in brain lesions of patients with multiple sclerosis. He's also found segments of TTV genomes in many cancer cell lines, including leukemia and Hodgkin's lymphoma lines, with no similar patterns in normal human tissues. He's found relatively high levels of complete TTV sequences in gastrointestinal, breast, lung cancers, as well as in samples of leukemia and myeloma. But the virus is also present at high levels in normal tissues.

Still, in TTV-infected tissues and cell lines, zur Hausen and de Villiers have found evidence of genomic rearrangements, and have linked a specific small region of TTV in cancer cells to truncated host cell genes. Given that studies have also linked TTV to immunosuppression and immunomodulation, chronic inflammation, prevention of apoptosis, and chromosomal aberrations, they suggest that TTV may act as an indirect carcinogen. Unlike human papillomavirus (HPV), which has a direct oncogenic effect on cells, TTV alone may not trigger disease -- but when combined with host factors such as higher levels of pro-inflammatory cytokines, and other diseases such as malaria, that recipe could create problems.