Undetectables --> Negative on RNA-PCR Test???

[0608]

Hi, guys.  I live outside the States, and I'm a member of several poz forums for people in the country where I'm living.

Recently, a guy put up a post that no one on the forum could really explain.  Here's the story.  The guy tested positive, started drug therapy, and became undetectable.  Then recently, he went through a mandatory work-related physical.  When he got the results back, he was shocked to see that HIV was one of the things that was tested for, and he was even more shocked to see that his result was negative.

So the guy went to his doctor who told him that undetectables could test negative depending on the screening test that was used.  He was confused, and so was everybody else on the forum who were all under the impression that even undetectables would always test positive on standard tests.

Curious about the story, I put on my Sherlock Holmes hat and dug through the forums here, and I came across mentions of the RNA PCR Test which to my understanding doesn't measure for antibodies like the other tests but looks for the virus itself (I hope I got that right).  So I'm wondering if undetectables CAN test negative on the RNA PCR Test, which would explain how that guy tested negative if that was indeed the screening test that was used by the place that he went to for the physical.

That's my amateur theory for now, but I wanted to ask for opinions on here before I tell the guy what I think.

[newt]

Standard diagnostic testing for HIV means 2 antibody tests using different methods....

All tests occasionally return false negatives (ie say the person doesn't have a condition when they do)....

For some PCR RNA tests this might be as high as 4 out of 100 times. This is why labs used by treatment clinics run PCR tests on several samples and PCR tests are not diagnostic of having HIV.

Finger stick and oral HIV antibody tests depend on operator skill and are prone to contamination and misinterpretation. It's easier to get a duff result on these tests. An HIV antibody test to be conclusive needs to test positive (or negative) on an two tests using different testing methods.

And sometimes an undetectable PCR test is reported as "negative" on the test slip, which does not mean "does not have HIV" but means "the quantity of virus is too low for the test to count".

So, depends what test the work outfit was using and whether they the tests were done properly and the results read right and how the results were reported.

It is more likely the test has been screwed up/misread than the guy on the forum is biologically interesting.

I have tested negative on an antibody oral test but tested positive from a follow-up blood test and was told by the nurse after a batch of follow-up tests "You're HIV positive but we can't measure any HIV in your blood. Are you on treatment?" Smart nurse << this was all part of a quality control programme

- matt