[Question #5897] Technical Hiv Test Question

20 months ago
Docs I’m hoping to make this simple and move on. I haven’t found anything online to answer me exact question. 

I had a HIV risk April of 2015.  I tested negative with the following:

(2) Oraquick Swab tests
(1) Oraquick Finger
(1) Alere determine 4th gen rapid
(1) Lab based 4th gen
(1) Aptima RNA Qualitative

Questions revolve around seronegative infection (not producing antibodies)

1.If I had not produced antibodies, would the Aptima had picked up the infection?

2. Do I need a Quantitative to diagnose seronegative or is qualitative the same exact test?

3. TMA as accurate as PCR?

Hoping to move on and not reply anymore ;)

Really just curious on the Aptima portion. I know both of your stance on the P24, but I just want a backup in case that failed as well.....and I’m thinking the Aptima Qualitative would do the trick....let me know please!
H. Hunter Handsfield, MD
H. Hunter Handsfield, MD
20 months ago
Welcome to the forum. Thanks for your question.

The basic presmise of your question is mistaken, for a couple of reasons.

First, there is no such thing as not producing antibodies in response to an HIV infection. It's an urban myth. With the early HIV tests, not used for 20 years or more, there were a few such cases -- even then it was rare. HIV infected people never fail to produce antibodies, and the newer tests never miss them.

Second, you had more than antibody testing. The two 4th generation tests are not measures of antibody alone, but also of HIV antigen -- i.e. a protein produced by the virus. In the theoretical scenario of no antibody being produced, the antigen component would be even mnore strongly positive than otherwise, and hence the test woudl be positive. This is the beauty of the AgAb (4th gen) tests and why they are now routine. They NEVER miss HIV when done 6+ weeks after the last exposure (and 98-99% of the time, 4 weeks). And RNA testing is another measure of the virus itself, not antibody. Almost everybody with HIV has positive RNA testing, unless on effective anti-HIV drugs.

Those comments pretty well cover your numbered questions, but to assure no misunderstanding:

1) As discussed, there's no such thing. But yes, in that event, both 4th gen tests and the RNA test would have detected HIV if you had it.

2) There is no quantitative test separate from qualitative. If qual is negative, HIV is absent and there's of course then no point in measuring how much HIV there is.

3) TMA and PCR are different kinds ot nucleic acid amplification test (NAAT). All NAATs are equally accurate.

Bottom line:  you have had all the "backup" testing you need. You dont' have HIV. Don't have any more tests.

I hope these comments are helpful. Let me know if anything isn't clear.

HHH, MD
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20 months ago
Doc,

Thank you soooo much for answering these questions. Just a couple of follow up questions that I would love your expertise and input on. 

1. I stumbled across a seronegative case that was published last month. It appears they only tested for antibody. What are you thoughts on this. Here is the link:


2. The only reason I was concerned about the quantitative vs. qualitative portion is because every time I read one of these articles about seronegative infection, they use a Quantitative PCR RNA Viral Load test. So I guess my question is Would the Qualitative RNA TMA also pick up the same infection if they used those tests instead?

Thank you for all of your help. You have no clue how much stress you have relieved. Best $25 I have ever spent. 
20 months ago
3. They test using plasma in these reports also. I’m not sure if they tested with my plasma or serum. Would either make a significant difference? Labcorp just says they could use either or. Not sure if one is more accurate. 
H. Hunter Handsfield, MD
H. Hunter Handsfield, MD
20 months ago
Thanks for that interesting case report. (However, I find it difficult to believe you "stumbled" across it! Obviously you were web seraching about HIV test reliability.) Indeed, the very first paragraph makes it clear the patient was negative for antibody only; the tests you had still would have been positive. I didn't read the entire report to the end, but the opening comments suggest the initial testing (in China) might not have been with standard commercial tests, approved by FDA in the US or China's FDA counterpart.)

All tests for HIV DNA start with a qualitative test, then move to quantitative if positive. That is, viral load testing always includes qualitative first and stops there if negative. To my knowledge, plasma vs serum makes no difference at all.

You don't have HIV It's time for you to let it go, including no more web searching. Like many anxious persons with internet access, you're obviously being selectively drawn to information that reinforces your fears. (The famous statistician Nate Silver, of fivethirtyeight.com, wrote a book, The Signal and the Noise. In it he covered this topic with something like this, an apprxomiate quote:  "Give an anxious person a comptuer with an internet connection in a dark room, and soon he'll be convinced his cold is the bubonic plague.")
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