Question about JC Virus titer

[rsinger]

I am JC positive. First test done 1 1/2 years ago came back with a titer of 1.12. Just had another test recently that came back as 0.77. Does anyone know how the titer can change like this. A few more points and I would be negative. I understand that once you are positive you will never be negative but I was surprised to see this difference in the two tests.
Anyone who understands this test please weigh in on this.

[Tomjadg]

Titer

Hi Rhonda

There will be more knowledgeable people that will respond, but from what I know, although it is unusual to go from positive to negative, it can happen. You have a good low number right now.

I have been a high positive (3.5) the last few checks, and I am getting another tomorrow, but I don't expect a change.

Good for you.

[rsinger]

titer

Thanks for your response Tomjadg. I thought it was strange that the titer would change so much. Can't wait to hear from others who may understand this. Are you on Tysabri? I have been on Tecfidera since July.

[LL60]

Thanks for your response Tomjadg. I thought it was strange that the titer would change so much. Can't wait to hear from others who may understand this. Are you on Tysabri? I have been on Tecfidera since July.

My titers have changed. They have been 4.1 and 2.2 and everything in-between. I think there are only theories on the whys. I think it may depend on where you are at in the 4 week period when you get tested. Mine went way down after I moved my infusions to every 6 weeks, but it has gone back up, so that blows that theory.

[Tomjadg]

Yes. I started on Rebif, but after 7 months of a steady decline, I switched to Ty. It's been about 2.5 years on Ty now.