Over the weekend, Mike South, a producer/director in the adult video business and Internet columnist, answered a question from a reader who asked him to explain the differences between the RT-PCR/PCR-DNA test(s) and the ELISA test. Since AVN is in the process of preparing a series of articles on healthcare within the adult industry, we asked AIM Healthcare Foundation executive director Sharon Mitchell to comment on South's answer to his correspondent's questions. What follows are South's answer, broken into its component parts, and Mitchell's comments on each part, with some amplification questions from AVN Senior Editor Mark Kernes:
Mike South: The Viral load tests measure the amount of virus in a blood sample by one of two methods. The first, the PCR is a process by which the RNA is chemically treated to cause it to replicate itself, the idea is to induce replication to a high level, then measure that level knowing that the replication factor is a constant. This is called an indirect test because it indirectly measures the amount of RNA in the sample.
Sharon Mitchell: That's a PCR-RNA test.
South: The second called bDNA, this is a direct measurement of the RNA. The sample is treated to induce the RNA to lumenesce [sic] or "glow" the amount of light given off indicates how much virus is present.
Mitchell: That's a branch DNA test, which is a form of an RNA test. It's still a viral load test. We do neither the bDNA nor the RT-RNA. We do PCR-DNA.
Mark Kernes: When Mike South says, "RT-PCR," that's incomplete? It has to say either RT-PCR-DNA or RT-PCR-RNA?
Mitchell: That's correct, and we do the PCR-DNA, not the PCR-RNA.
South: The problem with these tests is that they are only accurate to about forty parts per million, below that point the virus is undetectable. Someone who has HIV and has been on protease inhibitor drugs can fall well below this level and the tests determine them to be HIV Negative which they clearly are not. They are also most certainly still capable of passing on the virus to someone else.
Mitchell: That's all correct, bearing in mind that "forty parts per million" is equivalent of 400 copies per milliliter [see below], but it refers to the PCR-RNA test.
South: The ELISA test tests for antibodies to the virus to be present in your system, even though you may show no signs of illness 95% of all people will develope [sic] antibodies to HIV within 3 weeks of exposure.
Mitchell: No, no. In fact, some people can go without developing antibodies for six weeks to six months, and while six weeks may be great for the general population, it's not good for people having multiple partners in porn. And remember, we are using monitoring. We're not looking for a one guy/one time diagnosis here; we're looking for monitoring based on every 30 days by PCR-DNA — not RNA, not viral loads. That's why USA Referral [a testing referral service] is not a good facility for that very reason.
Kernes: So the first time someone came into you, if you gave them an ELISA test and it showed negative, they could actually have been HIV positive for up to six months and you would not necessarily be able to see it on the ELISA test?
Mitchell: Yes. That's why we don't use the ELISA test.
South: This "window period" is in reality no worse than that of the PCR tests, and may even prove better in some cases.
Kernes: He's talking about the PCR-RNA test, apparently.
Mitchell: Right, I know, and this is all relevant to PCR-RNA, but we don't do PCR-RNA. We can't afford to wait for the window periods of an ELISA or RNA.
Kernes: So an ELISA test and a PCR-RNA are really about the same in the sense —
Mitchell: No. One's an antibody test and one's a viral load test; they're two entirely different things, but they're not effective for this population when dealing with monitoring.
Kernes: So if someone had HIV and was not taking protease inhibitors, and got an ELISA test and a PCR-RNA, which one would be likely to detect the virus first?
Mitchell: Well, it depends. Now, remember, HIV is going to surge in the first 18-30 days, so if you're catching it early, HIV-RNA is going to show a sky-high viral load. But if we're not catching it early, there'll be some viral load and it will be relatively over 400 copies per milliliter, and that could occur any time, at any point. But usually when I've done the RNA tests, I've done them very early because I've done them as a confirmatory after ELISA, Western Blot and then RNA, after a positive PCR-DNA.
Kernes: So they're confirmatory tests for you?
Mitchell: For us, yeah.
Kernes: And even then, the tests may not confirm because depending on a variety of circumstances — how long the person has been positive; whether or not they're taking protease inhibitors — the only one that will actually show that they have the virus is the PCR-DNA.
Mitchell: Correct. In this case [see below], the RNA will mask the virus because they still have HIV but they're undetected, and the patient can still transmit the virus at least 15 percent of the time. Therefore, the one that we depend upon in case someone is trying to hide the fact that they have HIV is PCR-DNA, because it will always show the virus is detected.
South: I am surprised that AIM would not offer the ELISA test if you requested it, specially since it is the ONLY HIV test that is recognized by either the CDC or the AIDS Foundation as a valid HIV Screen.
Kernes: Why would you give the PCR-DNA in preference to the ELISA test or the PCR-RNA test?
Mitchell: Because of the window period. It's not three weeks; it can be minimum six weeks to as long as six months, and that's most of the time. Young, healthy people, for the antibody to mature, could take a lot longer than your average Joe, and we're dealing with young, healthy people between the ages of 18 and 25. And also remember, we're monitoring for the HIV disease every 30 days. That's key here. It's a monitoring system.
Kernes: Is the ELISA test the only test that's recognized by the CDC or the AIDS Foundation as a valid HIV screen?
Mitchell: I don't know.
South: PCR and bDNA testing are emphatically stated as NOT to be used as an HIV screen.
Mitchell: That may very well be, but again, they're dealing with average, everyday people, everyday tests for the general population. We are dealing with adult entertainers for pornography and this is a system that has kept HIV successfully out of porn since the inception of this Foundation in 1998.
South: Some companies and performers have been mislead [sic] by AIM so make sure that the person you are going to work with knows that you have not been tested by AIM, but have tests from a certified independent [sic] lab. I only accept an ELISA test but some in porn valley [sic] may only accept a PCR test, until they have been educated to the facts.
Mitchell: He's got the wrong facts. PCR-DNA is the one that will always show the virus. PCR-RNA is the one that hides the virus. I've got the proof right here.
[Note: To support her statements, Mitchell produced two tests given to the same HIV-positive individual who is currently taking protease inhibitors, the standard treatment for HIV: A PCR-RNA test, which indicates that the individual is "Within Range Result" with "Fewer than 400 copies/ml" of the virus, which would indicate to a physician who had no idea of the person's actual HIV status that the person was HIV negative; and a PCR-DNA test, which indicates that the person is "Outside of Reference Range" and is "Positive" for HIV.]
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Kernes: So if someone in porn attempted to work with just an ELISA test or just a PCR-RNA, what would be your advice to their partner or to the company that's employing them?
Mitchell: Do not do it. To a performer, I'd say you're putting yourself at risk because these two types of methods, ELISA and PCR-RNA, are hiding HIV at its earliest, and you may be working with someone that just has gotten HIV — it's not going to show up on either of those tests — or you may be working with someone that's HIV positive that's on medications and is not showing up on this RNA test, that can still transmit the virus 15 percent of the time. PCR-DNA test always will show up, and that's why we did this experiment here with Kevin.
Kernes: And on the PCR-DNA, the virus can show up within seven days?
Mitchell: No. Let's say minimum 14, to 30. We've seen it at 14 days.
Kernes: But it will definitely show itself by 30 days?
Mitchell: Absolutely.
