I was tested before starting Tysabri and was of course positive for the antibody. However, my disease was so aggressive and my neuro at Ohio State was conducting a research study on pts who were positive but treated anyway. He felt the potential benefits in my case outweighed the risks. The choice was mine ultimately but I agreed. I was on Tysabri for 6 months and continued to worsen. I did not have any reactions to the drug however. I ended up on Cytoxin (a chemotherapy drug) for six months to reboot my immune system...and now am back on Copaxone. Have had my first MRI with no new lesions in 3 years!!!!

A patient might not be informed that they are having a JC test done, but it is required as part of the pre-testing to start Tysabri therapy.

Yes I was tested and I believe my Dr will repeat it quarterly. Yes if you are positive you will always be positive but what is more important for the risk of PML is the amount of antibodies present in your system.

I had to be tested for JC virus, but the hospital where I take my infusions is also an MS center, so they had all of the needed information to monitor on site. Now that I am JC+ they test every 3 months, I believe.

The test wasn't available when I first started Tysabri. When it finally was available (2 1/2 years later), I tested positive. I made the difficult decision to continue receiving Tysabri as nothing else had worked at all.