11 Feb 2009 03:00 AM
Camouflaging Of Viral DNA Could Be Crucial Step In Progression Of Cancers
An estimated 15% of cancer cases can be linked to a viral infection, however the biological changes that cause some asymptomatic carriers of a virus to develop full-blown tumors are not well understood. In a study published online in Genome Research, scientists have mapped a chemical modification of DNA in three oncogenic viruses (Epstein-Barr, human papilloma virus, and hepatitis B virus) and found that the viral genome undergoes critical changes during the progression of disease, with implications for the development of new methods of prevention, diagnosis, and treatment.
Worldwide, most people are already infected with the Epstein-Barr virus, and millions are infected with the human papilloma virus and the hepatitis B virus. Many of these individuals will develop disease, and some will eventually develop a viral-related cancer such as lymphoma, liver cancer, or cervical cancer. Understanding how infections of viruses such as these can progress to cancer in some individuals is essential to the development of new methods to attack the virus and prevent malignancies.
Similarly to cellular organisms, the viral genome is subject to chemical modification. In animals, it is now appreciated that these "epigenetic" properties of genomes are variable in different tissues of the same individual, between identical twins, and in disease states. There are considerable efforts underway to map the landscape of epigenetic marks in the genomes of many organisms, yet it remains technically challenging to resolve the catalog of modifications at every base of DNA. However, significant clinical importance and a relatively small genome make viruses excellent targets for whole-genome epigenetic mapping.
In this study, an international team of scientists has determined the complete map of DNA methylation, a specific type of chemical modification, for the entire genome of the Epstein-Barr virus, the human papilloma virus, and the hepatitis B virus. Importantly, the researchers compared the DNA "methylomes" of asymptomatic carriers of each virus, patients with active infections, and patients harboring cancerous tumors…
Worldwide, most people are already infected with the Epstein-Barr virus, and millions are infected with the human papilloma virus and the hepatitis B virus. Many of these individuals will develop disease, and some will eventually develop a viral-related cancer such as lymphoma, liver cancer, or cervical cancer. Understanding how infections of viruses such as these can progress to cancer in some individuals is essential to the development of new methods to attack the virus and prevent malignancies.
Similarly to cellular organisms, the viral genome is subject to chemical modification. In animals, it is now appreciated that these "epigenetic" properties of genomes are variable in different tissues of the same individual, between identical twins, and in disease states. There are considerable efforts underway to map the landscape of epigenetic marks in the genomes of many organisms, yet it remains technically challenging to resolve the catalog of modifications at every base of DNA. However, significant clinical importance and a relatively small genome make viruses excellent targets for whole-genome epigenetic mapping.
In this study, an international team of scientists has determined the complete map of DNA methylation, a specific type of chemical modification, for the entire genome of the Epstein-Barr virus, the human papilloma virus, and the hepatitis B virus. Importantly, the researchers compared the DNA "methylomes" of asymptomatic carriers of each virus, patients with active infections, and patients harboring cancerous tumors…
