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PCR RNA question (please answer)

Question: 

Hello all, thank you for the great answers you guys give.

I have a quick question about the PCR RNA test. Do they need a sample of your blood from "before" an exposure to compare it to? Meaning do they need to see what/how your cells looked like before an exposure and then after to see if/how much of the virus is actually in you? I hope that makes sense.

question 2: If they do not need a before blood sample, what are they actually looking for? Does HIV actually have a distinct look?

Answer: 

Hi there, and thanks a lot for contacting the AIDS Vancouver Helpline for your HIV/AIDS related health information. It seems you have some questions about an HIV test you've had. We're happy to answer your question for you.

Here is a bit more information on the NAAT test:

Test Name
Method
Window Period
Conditions
NAAT (PCR RNA & DNA) Nucleic-Acid Amplification Testing (NAAT) looks for the genetic material of HIV and tests for it with a Polymerase Chain Reaction (PCR) test. 2-3 weeks post exposure NAAT tests generally take two forms: DNA PCR and RNA PCR tests. DNA PCR NAAT tests are usually used for screening babies of HIV+ mothers. RNA PCR NAAT tests are often used to screen blood or organ donations. Both measure the viral load of a positive person’s blood. Conclusive at 3 months post exposure.

You'll see in the chart that this is a test that "looks" for the genetic material of the virus in your blood. It is looking for the presence of specific sequences of viral DNA characteristic of HIV. Because the test is able to identify sequences of DNA specific to the virus, a sample of blood doesn't need to be taken prior to an exposure for comparison. So they aren't looking for viral particles directly under the microscope, but are looking for molecular signatures of the virus in your blood. We hope that makes sense.

Thanks a lot for contacting the AIDS Vancouver Helpline with your question, we hope it has been answered fully.

Trevor

AIDS Vancouver Helpline/Online
helpline.aidsvancouver.org