JC Virus – PML & MS patients taking Tysabri

From Medical News Today dated: Sep.11th.09
A very interesting discovery… that might help better understand and hopefully prevent the development of PML in MS patients using Tysabri.

The virus responsible for PML (progressive multifocal leukoencephalopathy), a rare brain disease that typically affects AIDS patients and other individuals with compromised immune systems, has been found to be reactivated in multiple-sclerosis patients being treated with natalizumab (Tysabri). The findings, led by scientists at Beth Israel Deaconess Medical Center (BIDMC), appear in The New England Journal of Medicine(NEJM).

“This virus – the JC virus, named for the initials of a patient – is found in about 90 percent of the population,” explains Igor Koralnik, MD, the study’s senior author and director of the Human Immunodeficiency Virus/Neurology Center at BIDMC. “But in healthy individuals the virus lies dormant in the kidneys and causes no problems.” Urine samples of healthy individuals may, therefore, show evidence of the benign virus.

But, according to Koralnik, who is also Associate Professor of Neurology at Harvard Medical School and a world leader in the study of PML, among AIDS patients and other patients with compromised immune systems, the JC virus can reactivate and travel to the brain, leading to the development of PML, a destructive brain disorder that may cause numerous neurological symptoms, including dementia, blindness, paralysis, and seizures. There is no cure for PML and more than half of all PML patients die within a year of diagnosis.

“This was the first time we had seen PML develop in patients with multiple sclerosis,” notes Koralnik. Because natalizumab, or Tysabri, prevents lymphocytes from crossing the blood-vessel wall, some doctors theorized that it was also providing an opportunity for the dormant PML virus to take hold. “The drug appeared to be something of a double-edged sword,” notes Koralnik. “Not only was it keeping dangerous cells from entering the brain, it was also keeping out the protective virus-fighting lymphocytes, thereby leaving patients vulnerable to this dangerous infection.

Their results showed that measurements of the JC virus in patients’ urine increased from 19 percent (before beginning treatment) to 63 percent after 12 months of using natalizumab. Six months later – 18 months after beginning treatment – blood samples further revealed that the virus had additionally entered the blood cells of 60 percent of these patients. (At 12 months of treatment, only one patient had the virus in their blood.)

“These JC virus measures were higher than viral measures found in patients infected with the HIV virus, and similar to measures seen in patients with full-blown PML,” explains Koralnik.

Finally, he adds, the scientists made another startling discovery: Further analysis showed that among many of the MS patients using natalizumab, the JC virus that was detected in their urine or blood samples had already acquired the signature changes associated with the virus’s ability to reach the brain and cause PML.

“This pilot study shows for the first time that natalizumab not only prevents the migration of protective T lymphocytes, but it also directly affects the cells’ potency against the JC virus,” says Koralnik. “It further tells us that reactivation and transformation of the virus may first occur in the kidney and that once the activated virus spills into the blood it can easily spread to the brain.”

“As of July 24, 2009, there was a worldwide total of 13 natalizumab-treated MS patients who had developed PML,” he adds. “We hope that the results of our study will stimulate further research, and that monitoring the appearance of the virus in the blood and urine may allow for early identification of natalizumab-treated patients at risk of developing PML.”
For all details follow the Medical News Today link under “Links”

6 Comments (+add yours?)

  1. Luisa Mendiola
    Nov 05, 2014 @ 23:03:29

    My friend has MS. She is on Tysabri. She just took a test to see if she has the jc virus and it came back positive. The nurse gave her a reading of 1.6. She could not explain if that was good or bad. Of course my friend is worried about PML. She recently had blood test for the liver and white blood cell count. Both were normal as was the rest of her blood test.. Do you know what the 1.6 signifies? my em


    • sofija
      Nov 06, 2014 @ 21:54:54

      hi Luisa!

      Your friend shouldn’t be too worried about the JC Virus positive result. As she can read from wiki: The virus is very common in the general population, infecting 70 to 90 percent of humans.. So most people have this virus, it just becomes a bit more of a “danger” to those of us on immunosuppressants.

      They have in the past years discovered that one can be tested for JCV-antibodies (blood test). I guess this is what she got? If these are low, then a patient will have a lower risk of developing PML even after 24 months on Tysabri. If these are high then of course the risk of PML is higher the longer one is on Tysabri/Natalizumab.

      You can read more here: http://www.medscape.com/viewarticle/806294

      And even download a PDF here:
      (I believe the numbers are pretty much the same as on page 2 in the above article)

      On that note, I wrote an updated article to the one you have read here:https://sofija.wordpress.com/2010/05/18/pml-update-may172010/

      I do need to update this topic, it has been 4 years… I believe that now more than before doctors are beginning to understand better the whole JCV influence on PML in Tysabri patients. However, they are also aware that JCV alone cannot be the sole determining cause of PML.

      I am a bit surprised the nurse didn’t explain more to your friend. She should at least see a doc for a proper explanation. I have had two JC Virus antibody tests this year and both came positive (of course, as before) and both were showing a low tier level. So both required a doctor’s appointment to “talk about my future & tysabri”. I, like many others, am VERY happy to be on Tysabri and wouldn’t wanna change it for anything else – so far this is the best medicine there is on the market for MS. Anyways, basically my doctor told me that I had more chances at getting hit by a car in traffic than getting PML. But I unfortunately dont remember the number, I checked my records too and there is no mention of it. (I will be getting my “shot” on Tuesday so I can ask the nurse what it is since she can see it in the records and will let you know then.)

      Do let me know if your friend has any more questions.. I hope I can help with what I know about MS so far.. Having a 10 year anniversary in a couple of months..yayks. But I am really happy with Tysabri, and if she is too she shouldn’t worry too much – though she should definitely talk to her Doc.



  2. Karen Black
    Mar 14, 2013 @ 18:17:16

    My husband was tested for this a month ago. and his test came back that he does have the virus. He had been on this treatment for 2 and a half yr.’s only being tested Onces,his dr told him he wanted to put him on it not knowing that he was all ready on it for a yr. For any one taking this treatment natalizumab witch we no has Tysabri. Stop takin it or make sure u get tested. thank’s.


    • sofija
      Mar 16, 2013 @ 18:43:54

      Thank you for your comment Karen!

      I am aware of the potential risks of taking Tysabri/Natalizumab while being positive for JCV but I opted to continue my treatment as it is still (unfortunately or not) the best medicine for MS on the market.. I was offered to go on Gilenya once the JCV was confirmed and reconfirmed and have opted not to, as I wasn’t impressed of the results.

      Hope your husband is doing well and I wish you both the best no matter the choice you take :)

      keep up the good spirit!


  3. Ufeud
    Jan 24, 2012 @ 04:38:55

    yes, they did that to me as well…normal blood test, takes about a month for the results…


  4. Trackback: You mean, I don’t have a choice? « Yulia's Special Place

Leave a Reply

Please log in using one of these methods to post your comment:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: