Q and A

Question

Do PCR and DUO tests pick up HIV-1 and HIV-2?

8 December 2011. Related: All topics, HIV testing.

I had an exposure in West Africa and want to test in London.

I had a PCR and 4th generation Elisa DUO test in Africa and they were negative but I was told that my PCR only looked for HIV-1 and that the the P24 antigen is only present in HIV-1 and therefore the DUO test also would not detect HIV-2 (which is common in West Africa).

OK, the antibody test in the Elisa DUO will look for both strains but I am worried about HIV-2.

Am I correct in what I say about the P24 antigen part of the test? Even if my PCR test was only designed for HIV-1 is there a chance it could still detect HIV-2 as they are similar?

Answer

Answer: Angelina Namiba

Thank you for your question

Both the PCR and the DUO tests look for all subtypes of the two strains, HIV-1 and HIV-2. It does not matter where you were infected geographically, these tests are designed to pick up any infection.

For more information on HIV tests please follow this link

Best wishes

15 comments

  1. Simon Collins •

    i-Base are no longer answering individual questions about testing. Please see the new i-Base guide to HIV testing and the risk of sexual transmission. This explains and discusses your question.
    http://i-base.info/home/new-i-base-guide-hiv-testing-and-risks-of-sexual-transmission/

  2. roy •

    hi,
    i have read all replies and comment..but i still want to know about the accuracy and reliance of the hiv duo test at 2 weeks. I had a risky event in late december and got tested with duo test after 2 week mark and it came negative.i consulted and they said it is conclusive n m not at risk. But still i m feeling low, plz advice..wt is the accuracy at 2 weeks. Should i go for a test at 4 weeks again? And if i go, will it b conclusive?
    Dasperately waiting for the reply……

  3. Simon Collins •

    See the testing FAQ. A test at 90 days is fine.

  4. ali •

    i had hiv dou test at 3 week….11week and 117 day from the risk.,….
    but i still have swelling tonsils on and off….and small oral trush…
    do i need more testing ??

  5. raj •

    Sir Is it true that DNA PCR targets the highly conserved region of HIV ( probably gag region )and it is 100 accurate and thats why it does not matter what subtype of hiv it is.

  6. raj •

    Sir but p24 dis sappers after initial phase of infection and reappears in late stage ? Are these viral protiens same in all the subtypes or structure of these proteins can change in different subtypes ? Please tell that does western blot detects all subtypes ?
    Thanks and Regards, Raj

  7. Simon Collins •

    The most common antigen is probably p24.

  8. raj •

    Is it true that most of antigen test in the world use gp120, gp41 ( envolope protiens for hiv 1) and gp36 ( hiv 2) as the basic antigens. do these mutates and can effect the diagnosis ? are these same in all subtypes and does not change ?

  9. Simon Collins •

    The antibody test will be sensitive to both HIV-1 and HIV-2. This is the most important aspect of testing.

  10. John Murphy •

    Thanks Angelina,

    However, I note and accept that the DUO test looks for the abtibody for HIV-1 and HIV-2. What I was wondering is if the P24 antigen part of the DUO test is relative to HIV-1 and ALSO HIV-2. My research would indicate that the P24 antigen part of the test would only pick up HIV-1 and NOT HIV-2.

    Also, I had a PCR test carried out but the report only said HIV-1. The lab scientist said it was not for HIV-2. Is there a specific, different PCR test for both strains or would a test just inadvertently pick both up anyway as they are similar?