Go to the address bar and write JC Virus. Look for the Wikipedia article.

Hi Felecia. I hve the JCV virus & I definitely can not take Tysabri.( it would be detrimental for me). It was only by the Grace & Mercy of God that my old MS doctor office asked me if I wanted to do a study for the JVC virus & they took blood sample & sent off to Duke Medicine & I tested positive for the JVC virus therefore I definitely can not Tysabri. I would suggest all who have MS to ask their doctor to test for the JVC virus. Hope this is helpful. Be Blessed!

Thank-you!