Aa
hiv pcr dna why and why not?
I want someone to explain about the PCR - it may NOT be a CDC approved diagnostic tool, ie it will will not show Antibodies , which provide the clinical definition of HIv + status - evidence of having contracted a virus (in essence having fought and defeated it, HIV being an exception amongst viruses as it is "unbeatable") .However, PCR DNA, testing for the actual genetic material of the virus in plasma is used in blood donations and the porn industry - now we know the risks of the extremely promiscuous porn actors and we know the aftermath of the blood for haemophiliacs disaster in the UK some years ago.So why would they have this in place now, considering the expense of each test?Why is it that the PCR DNA test , which is widely used in the period of initial /acute infection, not a diagnostic tool? Why does therefore even exist? Why do some doctors say that at 4 weeks if you have both a neg pcr dna and and a neg anti 1/2 test then you cannot be infected? If teh PCR DNA test is not fit for purpose,is it reasonable to assume therefore that blood is still being passed on for medical prurposes and may be contaminated? From what i have read pcr dna is unpopular for 2 reasons -a) cost b) false positives - NOT because it cannot detect the presence of the genetic material of teh hiv virus. Can someone please explain because it is teh source of confusion for a lot of people on here?
(And this is not a MOVE ON question - i believe it will benefit all round)
(And this is not a MOVE ON question - i believe it will benefit all round)
I agree that we are done arguing this as I don't want to aggravate you further even though you still don't understand the concept of off-label use in medicine.
About the Abbott RealTime HIV-1 Viral Load Test http://www.abbottmolecular.com/AbbottsHIV1ViralLoadTestApprovedbyFDAforUseonNewm2000MolecularDiagnosticsInstrument_26258.aspx "Read the last sentence in the following paragraph."
The Abbott RealTime HIV-1 assay, for use on the m2000 system, is among the most sensitive viral load tests available today, with a broad dynamic range, capable of quantitating HIV-1 in plasma down to as few as 40 RNA molecules per milliliter (mL) and up to as many as 10 million molecules per mL. The Abbott RealTime HIV-1 assay is intended for use in conjunction with clinical presentation and other laboratory markers as an indicator of disease prognosis and for use as an aid in assessing viral response to antiretroviral treatment as measured by changes in plasma HIV-1 RNA levels. This assay is not intended to be used as a donor-screening test for HIV-1 or as a diagnostic test to confirm the presence of HIV-1 infection.
Cobas AmpliPrep/Cobas TaqMan HIV-1 Test
http://www.natap.org/2007/newsUpdates/052407_11.htm "Read the last sentence in the following paragraph."
The test is intended for use in conjunction with clinical presentation and other laboratory markers of disease progress for the clinical management of HIV-1 infected patients. It can be used to assess patient prognosis by measuring the baseline HIV-1 RNA level or to monitor the effects of antiretroviral therapy by measuring changes in EDTA plasma HIV-1 RNA levels during the course of antiretroviral treatment. The test is not intended for use as a screening test for the presence of HIV-1 in blood or blood products or as a diagnostic test to confirm the presence of HIV-1 infection.
The Abbott RealTime HIV-1 assay, for use on the m2000 system, is among the most sensitive viral load tests available today, with a broad dynamic range, capable of quantitating HIV-1 in plasma down to as few as 40 RNA molecules per milliliter (mL) and up to as many as 10 million molecules per mL. The Abbott RealTime HIV-1 assay is intended for use in conjunction with clinical presentation and other laboratory markers as an indicator of disease prognosis and for use as an aid in assessing viral response to antiretroviral treatment as measured by changes in plasma HIV-1 RNA levels. This assay is not intended to be used as a donor-screening test for HIV-1 or as a diagnostic test to confirm the presence of HIV-1 infection.
Cobas AmpliPrep/Cobas TaqMan HIV-1 Test
http://www.natap.org/2007/newsUpdates/052407_11.htm "Read the last sentence in the following paragraph."
The test is intended for use in conjunction with clinical presentation and other laboratory markers of disease progress for the clinical management of HIV-1 infected patients. It can be used to assess patient prognosis by measuring the baseline HIV-1 RNA level or to monitor the effects of antiretroviral therapy by measuring changes in EDTA plasma HIV-1 RNA levels during the course of antiretroviral treatment. The test is not intended for use as a screening test for the presence of HIV-1 in blood or blood products or as a diagnostic test to confirm the presence of HIV-1 infection.
You are not a infant up to 18 months old, born to an HIV positive mother, and you were talking PCR-DNA tests not PCR-RNA tests which are approved as a supplemental test used in conjunction with an Anti-body test. We're done with this discussion on PCR-DNA tests.
http://www.avert.org/hivtesting.htm#q7a
What are NAT, DNA, RNA and PCR tests?
HIV tests that detect the genetic material of HIV itself (rather than antibodies or antigens) are known as PCR tests. PCR stands for Polymerase Chain Reaction and is a common way of testing for a variety of different organisms. The overall process of extracting and amplifying the genetic material of an organism (in this case HIV) and then testing for it with a PCR test is called Nucleic-acid Amplification Testing or NAT. NAT tests generally take two forms: DNA PCR tests and RNA PCR tests.
RNA PCR tests are most frequently used for screening blood donations and donor organs for HIV, while DNA PCR tests are used for testing newborn babies born to HIV positive mothers. Both types of test can be used to measure the amount of virus that is present within a person's body (when they will usually be referred to as 'viral load' tests). NAT is sometimes also offered for diagnosing individuals, but because it is costly and complicated to perform, antibody testing is far more common in testing clinics.
NAT generally gives positive results much sooner than standard antibody testing would, making it useful in situations where early diagnosis is necessary. An RNA PCR test will produce a positive test result within two to three weeks. A DNA PCR test will provide positive results within three to four weeks (sometimes sooner). As long as the recommended amount of time has elapsed before taking the test (people taking the test for personal diagnosis should ask their testing clinic if they are unsure), the test will be able to give a very accurate result. False positive results are more common than false negatives due to the PCR test's sensitivity, so all positive results must be double checked using a standard antibody test.
What are NAT, DNA, RNA and PCR tests?
HIV tests that detect the genetic material of HIV itself (rather than antibodies or antigens) are known as PCR tests. PCR stands for Polymerase Chain Reaction and is a common way of testing for a variety of different organisms. The overall process of extracting and amplifying the genetic material of an organism (in this case HIV) and then testing for it with a PCR test is called Nucleic-acid Amplification Testing or NAT. NAT tests generally take two forms: DNA PCR tests and RNA PCR tests.
RNA PCR tests are most frequently used for screening blood donations and donor organs for HIV, while DNA PCR tests are used for testing newborn babies born to HIV positive mothers. Both types of test can be used to measure the amount of virus that is present within a person's body (when they will usually be referred to as 'viral load' tests). NAT is sometimes also offered for diagnosing individuals, but because it is costly and complicated to perform, antibody testing is far more common in testing clinics.
NAT generally gives positive results much sooner than standard antibody testing would, making it useful in situations where early diagnosis is necessary. An RNA PCR test will produce a positive test result within two to three weeks. A DNA PCR test will provide positive results within three to four weeks (sometimes sooner). As long as the recommended amount of time has elapsed before taking the test (people taking the test for personal diagnosis should ask their testing clinic if they are unsure), the test will be able to give a very accurate result. False positive results are more common than false negatives due to the PCR test's sensitivity, so all positive results must be double checked using a standard antibody test.
Pull up any test that is a PCR-DNA test an show everyone here where it states for diagnostic use.
i deliberately never said all viruses , ok maybe it came across as meaning that , but I certainly didnt mean. Actualy influenza is not such a good example to cite as there are so many strains of what we refer to as the flu, i had a flu jab a few years back and i still get other kinds of flu. I was thinking more in terms of smallpox or viruses that typically are dealt with by innoculation or by immune system response and the body will always have a presence of antibodies to these thereafter without re-infection.
It wasnt a stone throwing exercise at Teak, I asked a question because i needed clarificaton and was told to move on. If you did that at school, what would you learn ? nothing. My point is that the test has to have a diagnostic value and exists for a reason.Yes there are false positives but a test that produces false positives is more desirable from a safety point of view than one which produces false negatives. Even the orasure 20 minute tests carry the risk of false positives. Psychologically for the person being tested it must be a headfcuk but in science you never really on one test result and all pos tests require retesting by alternative method.
Bynack thanks for the you-should-never-have-put-yourself-at-risk comment. Apply that to everyone on here would you? Fact is high risk or not, almost every unprotected sexual act carries a risk of some kind. Do you think anyone who is on this forum actually wants to have ended up on here? your comment is not helpful.
Anyway my point again, whilst not being a stand alone diagnostic test ,the pcr dna is nonetheless a diagnostic test - does it or does it not show genetic material of HIV in infected individuals at early stages of infection?
And would it not be better to offer this plus 1 other type of test to individuals at 6 weeks instead of 12 (look at the amount of anxiety and mental trauma on these forums).
It wasnt a stone throwing exercise at Teak, I asked a question because i needed clarificaton and was told to move on. If you did that at school, what would you learn ? nothing. My point is that the test has to have a diagnostic value and exists for a reason.Yes there are false positives but a test that produces false positives is more desirable from a safety point of view than one which produces false negatives. Even the orasure 20 minute tests carry the risk of false positives. Psychologically for the person being tested it must be a headfcuk but in science you never really on one test result and all pos tests require retesting by alternative method.
Bynack thanks for the you-should-never-have-put-yourself-at-risk comment. Apply that to everyone on here would you? Fact is high risk or not, almost every unprotected sexual act carries a risk of some kind. Do you think anyone who is on this forum actually wants to have ended up on here? your comment is not helpful.
Anyway my point again, whilst not being a stand alone diagnostic test ,the pcr dna is nonetheless a diagnostic test - does it or does it not show genetic material of HIV in infected individuals at early stages of infection?
And would it not be better to offer this plus 1 other type of test to individuals at 6 weeks instead of 12 (look at the amount of anxiety and mental trauma on these forums).
Incorrect information again? Show one, just one PCR-DNA test that is approved for diagnostic use. Western Blot test has nothing to do with monitoring a persons HIV progression. Two totally different tests used for two totally different purposes.
Yes, a test with false positives cannot be used as a stand alone test, just like ELISA. But that doesn't mean it doesn't have diagnostic utility.
WB is the gold standard and provides confirmation but is not typically used as a stand alone test but as part of a diagnostic algorithm in which either ELISA or PCR (in rare situations where the cost is justified) are used in conjunction
PCR is used as part of the diagnostic process, it just serves a different purpose than the WB- it shortens the window period for detecting samples that may be infected.
WB is the gold standard and provides confirmation but is not typically used as a stand alone test but as part of a diagnostic algorithm in which either ELISA or PCR (in rare situations where the cost is justified) are used in conjunction
PCR is used as part of the diagnostic process, it just serves a different purpose than the WB- it shortens the window period for detecting samples that may be infected.
A POS PCR would be always followed up with an antibody test (most likely a Western Blot) at the appropriate time to rule out or confirm infection. It is not a stand-alone test for people testing in the community.
This is why you see "it is not a diagnostic test" over and over in this forum.
This is why you see "it is not a diagnostic test" over and over in this forum.
Sigh. I knew I shouldn't be watching this forum.
NAT/PCR IS used for diagnostic purposes for individuals at particular high risk (MSM with multiple partners) to detect early infection at certain clinics such as Dr. HHH's former clinic. It is tested on pooled samples first to save on costs.
PCR tests are used to diagnose the presence of a number of infectious organisms, including chlamydia and gonorrhea and are also used (as the OP correctly states) in diagnostic situations such as screening blood donations for HIV. Again, it is used on pooled blood samples to save on costs.
Of course it's a diagnostic test. It's just not recommended as the standard test for the vast majority of people who get tested for HIV (who are not at particularly high risk) because the cost and false positive issues already cited here do not justify it.
NAT/PCR IS used for diagnostic purposes for individuals at particular high risk (MSM with multiple partners) to detect early infection at certain clinics such as Dr. HHH's former clinic. It is tested on pooled samples first to save on costs.
PCR tests are used to diagnose the presence of a number of infectious organisms, including chlamydia and gonorrhea and are also used (as the OP correctly states) in diagnostic situations such as screening blood donations for HIV. Again, it is used on pooled blood samples to save on costs.
Of course it's a diagnostic test. It's just not recommended as the standard test for the vast majority of people who get tested for HIV (who are not at particularly high risk) because the cost and false positive issues already cited here do not justify it.
virus (in essence having fought and defeated it, HIV being an exception amongst viruses as it is "unbeatable"
Actually, this statement is incorrect. Almost every virus in the world has no "cure". There are treatments, and most viruses do not cause as serious complications, but HIV is not "the only virus without a cure", or "unbeatable"...not by far.
Example...common cold virus and influenza. Both viruses, no cures.
Actually, this statement is incorrect. Almost every virus in the world has no "cure". There are treatments, and most viruses do not cause as serious complications, but HIV is not "the only virus without a cure", or "unbeatable"...not by far.
Example...common cold virus and influenza. Both viruses, no cures.
COMMUNITY LEADER
Building on what Teak has said, yes PCR is not the test recommended for primary screening of the infection, but is a clinical tool for monitoring of the disease progression, and treatment efficacy done, along with other tests like CD4 counts etc. This is a test for those already infected.
Relatively higher probability of false positive, significantly high cost (in my country, it is 15-20 times higher than a simple ELISA anti body test) and other clinical reasons, antibody test still remain the top choice for primary diagnosis of the infection with a confirmation run by Western Blot.
Relatively higher probability of false positive, significantly high cost (in my country, it is 15-20 times higher than a simple ELISA anti body test) and other clinical reasons, antibody test still remain the top choice for primary diagnosis of the infection with a confirmation run by Western Blot.
You're wrong about the GUM clinic and the UK. They use the same guidelines as we use in the US.. No I don't turn on anything that is proven correct and you haven't proved your point and the point is that PCR-DNA test are NOT diagnostic tests they are monitoring tests for people that are infected with HIV to monitor their progression.
No, but when you or anyone talk about the 3 month testing window (q"Your 3 month test will be conclusive"uq) you are talking about the CDC guidelines - these arent applied in Australia, France , many GUM clinics in UK and various other locations. There HAS to be reasons why sone tests exist and other tests are used and at what time frame and with what degree(s) of reliablity. There are doctors on the Ask a doctor forum who will disagree with what you consistently cite.
Teak you turn on anyone who questions the status quo ref testing as if theyre an AIDS denialist or have a psychiatric disorder.I am neither.
Why can you not answer my question? its a series of questions not a statement and a lot of people are confused (including me) about testing , test types, timeframes and frankly mate youre not doing anything to help. So dont insult me please with a one-liner.
So are you going to address some of my questions with some valid scientific evidence or are you going to ban me/time me out?
Thanks
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