The human papilloma virusThe smallest type of organism known. A single virus particle (called a virion) is much smaller than a cell. Viruses reproduce by invading cells and forcing the cells to make progeny virions. Viruses generally have specific host cells which they infect. Some virus types are associated with specific cancers and can convert normal cells into cancer cells. Examples of viruses associated with cancer are: papillomavirus-cervical cancer, hepatitis virus-liver cancer, Epstein-Barr virus-Burkitt's lymphoma. Virus-induced transformation of cells was one of the very first model systems for the study of cancer. Viruses have also been a key tool in the identification of many oncogenes. Because of their great ability to enter target cells viruses such as adenoviruses are being examined for their ability to deliver genes to cancer cells. (HPV) has recently come to national attention with the advent of the HPV vaccine, which is now in use both in the U.S. and abroad. Although the vaccine has largely been marketed as a means of preventing cervical cancer, some strains of HPV are also associated with an increased risk of mouth cancer. The HPV16 strain is linked with both cancers, and a recent study from the University of Manchester has revealed a key step in the cancer formation process. Cells containing the HPV E6 proteinOne of the four basic types of biomolecule. Proteins are polymers made up of strings of amino acids. Proteins serve many functions in organisms including transport of molecules, structure, cell adhesion and as signaling molecules such as hormones. Many transcription factors, including p53 and Rb are proteins. showed increased activity of Cdc42, a protein involved in regulation of cell division and one that is often found at high levels in cancer cells.
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