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Category: Clinical Microbiology
Human Immunodeficiency Viruses * , Page 1 of 2
< Previous page | Next page > /docserver/preview/fulltext/10.1128/9781555816728/9781555814632_Chap79-1.gif /docserver/preview/fulltext/10.1128/9781555816728/9781555814632_Chap79-2.gifAbstract:
The human immunodeficiency virus (HIV) is the etiologic agent of AIDS. HIVs are enveloped plus-stranded RNA viruses. The HIV genome is organized similarly to other retroviruses. It contains the gag, pol, and env genes which encode structural proteins, viral enzymes, and envelope glycoproteins, respectively. The major structural proteins which are encoded by the gag gene include p17, p24, p7, and p9. Replication begins with the attachment of virus to the target cell via the interaction of gp120 and the cellular receptor CD4. Both HIV-1 and HIV-2 have the same modes of transmission. The most common mode of HIV infection is sexual transmission at the genital mucosa through direct contact with infected blood fluids, including blood, semen, and vaginal secretions. Serological testing for HIV antibody is used for various purposes, including primary diagnosis, screening of blood products, management of untested persons in labor and delivery, evaluation of occupational exposures to blood/body fluid, and epidemiological surveillance. The first generation of HIV antibody assays relied on the detection of antibody to HIV viral protein lysates. A test using a sandwich-capture format and significantly more blood than other methods was more sensitive in early seroconversion. HIV-1 RNA load testing is sometimes requested to resolve equivocal serologic findings or to facilitate the diagnosis of HIV-1 infection during the acute phase or in a pediatric setting.
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Schematic representation of a mature HIV virion showing the localization of viral proteins.
Schematic representation of a mature HIV virion showing the localization of viral proteins.
Time course of appearance of markers of HIV infection during the course of HIV infection.
Time course of appearance of markers of HIV infection during the course of HIV infection.
HIV antibody testing algorithm for samples initially reactive in a standard HIV-1/HIV-2 assay showing the sequence of suggested follow-up confirmatory testing. LIA, line immunoassay.
HIV antibody testing algorithm for samples initially reactive in a standard HIV-1/HIV-2 assay showing the sequence of suggested follow-up confirmatory testing. LIA, line immunoassay.
HIV antibody testing algorithm for samples tested with rapid HIV assays. LIA, line immunoassay.
HIV antibody testing algorithm for samples tested with rapid HIV assays. LIA, line immunoassay.
Examples of HIV-1 Western blot results. Samples with high and low positive results are shown in lanes 1 and 2, respectively. An indeterminate Western blot is illustrated in lane 3. A negative control is shown in lane 4.
Examples of HIV-1 Western blot results. Samples with high and low positive results are shown in lanes 1 and 2, respectively. An indeterminate Western blot is illustrated in lane 3. A negative control is shown in lane 4.
Major HIV-1 and HIV-2 gene products
Major HIV-1 and HIV-2 gene products
Comparison of FDA-approved HIV-1 viral load assay characteristics
a For tests that use an automated extraction instrument (AmpliPrep and RealTime), the specimen volume listed refers to the volume of sample that is loaded on the instrument, which is greater than the actual volume of specimen taken through the extraction.
b Nucleic acid sequence-based amplification.
Comparison of FDA-approved HIV-1 viral load assay characteristics
a For tests that use an automated extraction instrument (AmpliPrep and RealTime), the specimen volume listed refers to the volume of sample that is loaded on the instrument, which is greater than the actual volume of specimen taken through the extraction.
b Nucleic acid sequence-based amplification.
Major FDA-approved HIV-1/HIV-2 laboratory-based serodiagnostic tests a
a Data from reference 155 and http://www.fda.gov/BiologicsBloodVaccines/BloodBloodProducts/ApprovedProducts/LicensedProductsBLAs/BloodDonorScreening/InfectiousDisease/ucm080466.htm.
Major FDA-approved HIV-1/HIV-2 laboratory-based serodiagnostic tests a
a Data from reference 155 and http://www.fda.gov/BiologicsBloodVaccines/BloodBloodProducts/ApprovedProducts/LicensedProductsBLAs/BloodDonorScreening/InfectiousDisease/ucm080466.htm.
Rapid and point-of-care HIV tests approved for use in the United States a
a FDA-approved rapid HIV tests as of May 2009. Data derived from the CDC at http://www.cdc.gov/hiv/topics/testing/rapid/rt-purchasing.htm and http://www.cdc.gov/hiv/topics/testing/rapid/rt-comparison.htm and from manufacturers' package inserts and FDA data.
Rapid and point-of-care HIV tests approved for use in the United States a
a FDA-approved rapid HIV tests as of May 2009. Data derived from the CDC at http://www.cdc.gov/hiv/topics/testing/rapid/rt-purchasing.htm and http://www.cdc.gov/hiv/topics/testing/rapid/rt-comparison.htm and from manufacturers' package inserts and FDA data.
Causes of false-positive EIA, false-negative EIA, and indeterminate Western blot HIV antibody results
a In acutely infected individuals treated with antiretroviral therapy.
Causes of false-positive EIA, false-negative EIA, and indeterminate Western blot HIV antibody results
a In acutely infected individuals treated with antiretroviral therapy.
HIV-1 resistance assays
HIV-1 resistance assays