HIV-1 RNA and HIV-2 RNA assays are offered to confirm HIV-1 or/and HIV-2 infections for patient samples with undifferentiated HIV antibody status and to monitor antiretroviral therapy. Acute HIV-1 infections are confirmed with the HIV-1 RNA assay (Abbott RealTime HIV-1 assay). The Retrovirology Laboratory within the University of Washington Department of Laboratory Medicine offers a new algorithm for the laboratory diagnosis of HIV using a fourth generation HIV screening assay (Abbott Architect HIV Ag/Ab Combo Assay) and an HIV-1/-2 differentiation assay (Bio-Rad Multispot HIV-1/HIV-2 Rapid Test) to confirm the presence of HIV-1 or/and HIV-2 antibodies. See HIV-1 RNA Quant by Real Time in the Online Guide to Lab Testing. *The dynamic range for HIV RNA quantitation by US-RT-PCR is 50 to 100,000 copies/mL of plasma. To provide HIV RNA quantification for non-clade B viruses, the Roche Monitorª US-RT-PCR version 1.5 assay should be ordered. HIV clade B is the predominant virus causing HIV/AIDS in North America and Europe. *The dynamic range for HIV RNA detection by Real-Time RT-PCR is 30 to 1,000,000 copies/mL of plasma. The Real-time RT-PCR assay for HIV RNA quantification has been validated against the commercial bDNA and ultrasensitive (US) RT-PCR assays. To quantify HIV RNA, the UW Clinical Retrovirology Laboratory uses a real-time reverse transcription (RT)-polymerase chain reaction (PCR) amplification platform with enhanced sensitivity and broader dynamic range compared to available commercial assays. Inhibition of cell-free HIV, as reflected by RNA copy number, is associated with better CD4 response and clinical response in some patient populations. However, in conjunction with a positive DNA PCR or a reactive EIA, the RNA quantitation may be diagnostic.) High levels of RNA are found during acute infection and in patients who are more likely to have disease progression. (Alone, this assay is not recommended nor approved for diagnosing HIV infection. HIV RNA quantitation may be useful to indicate when an HIV infected person should start anti-retroviral therapy and when such therapy should be adjusted. Quantitation of HIV RNA copy number is available to monitor antiviral therapy and to predict disease progression in HIV infected persons. See Human Immunodeficiency Virus 1 & 2 in the Online Guide to Lab Testing. HIV-1 Western blot confirmation assays are run on Tuesday, Thursday and Friday. HIV-1 and -2 EIA screens are run daily, Monday through Friday. Specimens may be forwarded, upon request, for HIV-2 specific Western blot if supplemental assays indicate HIV-2 antibodies may be present. Supplemental assays are performed on EIA-reactive specimens which do not confirm by HIV-1 Western blot. no antibodies reacting to either HIV-1 or non-HIV-1 proteins. A negative Western blot has no detectable bands, i.e. Specimens showing reactivity to non HIV-1 proteins are not assigned an indeterminate status but are instead reported as “Antibody to non-HIV-1 encoded proteins”. All indeterminate Western blots are further tested in supplemental HIV-1 and HIV-2 specific assays. Specimens showing reactivity to HIV-1 protein(s), but not fulfilling the criteria for a positive result, are reported as Indeterminate. These criteria require antibodies against any two of the following HIV-1 proteins: p24, gp41, gp120/160. Criteria accepted by CDC/ASTPHLD are used for determining a positive HIV Western blot. The HIV Western blot identifies antibodies against eight HIV-1 encoded proteins: p18, p24, p31, gp41, p51, p55, p65/66, gp120/p160. Reactive results are confirmed by HIV-1 Western blot. Antibodies to HIV-1 and HIV-2 are detected by enzyme immunoassay (EIA).
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