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NAT test

Aug 5, 2007

Dr. Bob, some states actually use a nat test along with an antibody test to check subjects for hiv. They take two viles of blood for this. Can you tell me what a nat test checks for ?

Response from Dr. Frascino


Sure. See below.

Dr. Bob

nucleic acid testing May 16, 2006

dr. bob, i'm a 25 year old guy who made a mistake and had brief unprotected insertive anal sex about 5 weeks ago. The guy also had his penis around my anus- but not in. Of course, I'm beating myself up and my anxiety is really kicking up right now. I had an hiv test and std screenings at one week. All negative/non reactive. My anxiety got very bad and my dr. recommended having a nucleic acid test at 3 weeks if that was the case. I found a program at the los angeles gay and lesbian center that offers free diagnostic nat for hiv. I went about 10 days ago and get the results tomorrow. I know you don't recommend this as a means of diagnosis, but I wanted to know what you know of the testing they offer and whether or not it is reliable. also, is the chance for a false positive still high as i believe it is a pooled nat test?

whether or not you answer this, thanks for all your help and support, you've gotten me through a scare once before and hopefully i'm a day away from woohooing again. or at least a woo. you really are an angel.

Response from Dr. Frascino


Yes, I am aware the Gay and Lesbian Center in Los Angeles began offering free nucleic acid amplification testing (NAT). I believe they are the first site in Los Angeles County to do so! By report, this testing assay, which detects actual HIV rather than antibodies to the virus, can give accurate results within three to four weeks, compared to three months for standard HIV-antibody tests, such as ELISA. I do not have specific information about the rate of false-negatives or false-positives for the specific testing assay the center is using. However, chances are the folks at the center would be able to provide you with whatever information has been generated so far. I do believe the general testing assay (NAT) is indeed valid. More information should be available fairly soon if this type of testing becomes more widespread and available. I'll try to keep you posted as reliable information evolves.

Good luck!

Dr. Bob

Three New Assays Approved

May 25, 2007

On May 23, 2007, FDA approved the Procleix Ultrio Assay on the fully automated Procleix TIGRIS system manufactured by Gen-Probe Inc., of San Diego, California, and marketed by Chiron Corporation. This is a fully automated qualitative in vitro nucleic acid test (NAT) to screen for human immunodeficiency virus type 1 (HIV-1) and hepatitis C virus (HCV) RNA in donated blood from donors of whole blood, blood components, or source plasma. It is also licensed to screen individual organ donations from living donors, heart-beating organ donors, and cadaveric (non-heart-beating) organ donors. The capability of full automation will reduce human error and accelerate blood screening, enhancing blood safety.

On May 11, 2007, FDA granted marketing approval to two HIV-1 PCR assays for use in managing the treatment HIV infection.

The Abbott RealTime HIV-1 Assay, made by ABBOTT Molecular, Inc., is an in vitro reverse transcription-polymerase chain reaction (RT-PCR) assay for the quantitation of Human Immunodeficiency Virus type 1 (HIV-1) on the automated m2000 System in human plasma from HIV-1 infected individuals over the range of 40 to 10,000,000 copies/mL. The Abbott RealTime HIV-1 assay is intended for use in conjunction with clinical presentation and other laboratory markers for 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. (Product label)

The COBAS AmpliPrep/COBAS TaqMan HIV-1 Test, made by Roche Diagnostics is an automated PCR test, indicated for the quantitation of Human Immunodeficiency Virus Type 1 (HIV-1) nucleic acid in human plasma (viral load) for use in conjunction with clinical presentation and other laboratory markers. 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 plasma HIV-1 RNA levels during the course of antiretroviral treatment. (Product label)

Neither the Abbott RealTime nor the COBAS AmpliPrep/COBAS TaqMan HIV-1 assay is 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.

HIV Risk
Still need testing, worried and depressed (FALSE POSTIVE HIV PCR)

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