Anyone test negative for JCV after testing positive for five months?

[ksl]

Hi,

Curious if anyone has has this experience or can offer an explanation.

In Oct 2013 I test negative for JCV, as I had been since starting infusions over three years ago.

Fast forward to March 2014 when I tested positive, with a titer of .33.

Every month from April to July. I tested positive, my titers ranging from .27-.43 during that time.

Aug. JCV came back negative. How does that happen? False negative?

I am planing on coming off Tysabri, and trying Rituxan, though now I am more confused about what to do.

Would appreciate any thoughts, or comments.

Thanks

[ru4cats]

I don't know if I can help much, but I had my 6 month checkup with my neurologist last week. She told me there is a 2% false positive, 2% false negative, and a 2% conversion from negative to positive and vice versa on every test an individual takes. I've had at least 6 tests, and I'm still negative.

I do know from what I've read on this site that your titer level is very low compared to many others to have chosen to stay on Tysabri. It is still the most effective drug for MS.

[Myoak]

It is understandable that there is some confusion about JCV antibody testing.

A JCV index of less than .20 is considered negative. So you can test .19 for JCV antibodies and you are classified as negative. A number like .19 would normally indicate the presence of something to us commoners but the guidelines say "an index value of less than .20 indicates that no antibodies to JCV were detected."

Therefore, we realize the test is not positive or negative, plus or minus, based on zero as negative and anything more as positive. We have to get clear on that point or the test will never make sense. People who test .39 are not classified as positive; they are indeterminate. Anyone who tells you otherwise, including your neuro, has chosen not to follow the guidelines set by those who developed the JCV antibody index test.

KSL, you did not test positive with a .33 titer; a .33 titer falls in the category of indeterminate. It is not unusual for antibody levels to fluctuate around such small numbers. People do sometimes test positive (over .40) and later test negative (under.20) and vice-versa.

As we age it is logical that we have more opportunity for exposure to JC virus and build antibodies to it. Between the ages of 1 and 5, approximately 10% of children are JCV antibody positive; between the ages of 20 and 50 about 50-60% are JCV positive.

No one knows how JCV is spread, some speculate respiratory transmission, some suggest saliva but no one knows. The mechanism of viral spread remains unknown.

I will directly quote from guidelines explaining JCV index interpretation recommendations developed from “A second-generation ELISA (STRATIFY JCV™ DxSelect™) for detection of JC virus antibodies in human serum and plasma to support progressive multifocal leukoencephalopathy risk stratification.”

Index Interpretation Recommendation

>0.40 Positive A specimen with an index value of > 0.40 is positive for the presence of antibodies to JCV.

Indeterminate: A specimen with an index value of ≥0.20 but ≤0.40 is considered an indeterminate result.

<0.20 Negative* An index value of < 0.20 indicates that no antibodies to JCV were detected.

KSL, one thing to keep in mind is that studies have demonstrated that very low titers of JCV, specifically under .90, carry very little risk of PML. The risk is so small that an index of under .90 is generally compared to being JCV negative.

That finding was very important because people under .90 were getting scared out of their shorts and switching to less effective meds out of unwarranted fear. That unwise course accelerated MS needlessly for people I know personally.

KSL, don’t let anxiety chose your treatments. Wait until you are settled, thinking clearly and at peace when you chose a new direction.

Treatment decisions are tormenting difficult in MS. The decision giving you the most peace is probably the best one for you. Good luck. You have all my best wishes.

[ru4cats]

Thanks, Myoak. I always learn so much from your entries, and I appreciate your contributions.