This is the JC virus, of which 65% of children under 14 years of age are infected, although the infection does not cause symptoms in the majority of cases. The authors have observed that some medulloblastomas contain one or two proteins of the virus.
They have been studying the JC virus for 20 years, since in immunocompromised people it can lead to a fatal disease of the nervous system. One of the things they have proven, as published in the "Journal of the National Cancer Institute", is that when the virus is injected into the brains of experimental animals it can lead to the development of different types of tumor.
Studying these tumors, researchers found that a protein that the JC virus produces when it infects a cell is present in some medulloblastomas. The protein is known as T antigen and is a well-studied cancer-causing agent.
In their research they also observed that a second protein of the virus, called agnoprotein and whose function is unknown, is present in some tumors. They examined tumor samples and found that the gene that produces agnoprotein was present in 11 of the 16 samples (69%), and the T antigen gene was present in 7 (44%).
