HIV-1 Proviral DNA Qualitative Detection by PCR, Blood
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Human immunodeficiency virus (HIV)-1 infection in humans is usually confirmed by detection of HIV-1-specific antibodies in serum. However, serologic testing may not reliably identify HIV-1 infection in neonates with passively acquired maternal HIV-1 antibodies or with incompletely developed immune systems, in individuals with early infection (<30 days from infection), or with "indeterminate" antibody profiles by Western blot assays. In these situations, detection of HIV-1 nucleic acids (RNA or proviral DNA) by PCR can provide early evidence of HIV-1 infection (approximately 10-14 days after infection), when results of routine diagnostic assays are inconclusive.
Upon entry into human cells (including peripheral blood mononuclear cells), the HIV-1 RNA is converted into complementary DNA (cDNA) by reverse transcription. These linear cDNA strands are then integrated into the host cell genome, thus representing the proviral form of HIV-1. mRNA, transcribed from the proviral DNA, is used to synthesize the proteins required to make new viral particles. These proteins and viral RNA are packaged in the host's cytoplasm and released from the cell, completing the life cycle of the virus.
The presence of integrated HIV-1 proviral DNA can be detected by a PCR that targets a segment of the highly conserved HIV-1 gag gene. Clinical studies have indicated that detection of HIV-1 proviral DNA in whole blood specimens by PCR is highly sensitive (>95%) and specific (>98%) for the presence of early HIV-1 infection in infants <2 years old.
HIV-1 virologic testing is recommended at birth, 1 to 2 months of age, and 6 months after birth, in infants born to HIV-1-infected mothers. Two serially positive HIV-1 virologic test results (HIV-1 proviral DNA or HIV-1 RNA) are necessary for the diagnosis of HIV-1 infection in infants <2 years of age.
Virologic detection of HIV-1 infection in infants of <2 years of age (an age group for which serologic tests are unreliable) born to HIV-1-infected mothers
Early detection of HIV-1 infection in children and adults prior to appearance of HIV-1 RNA, HIV-1 p24 antigen, or HIV-1 antibodies in blood
Determining eradication of HIV-1 in individuals receiving investigational highly active antiretroviral therapies
A positive result is consistent with HIV infection (see Cautions). Two serially positive HIV-1 virologic test results (HIV-1 proviral DNA or HIV-1 RNA) are necessary for the diagnosis of HIV-1 infection in infants <2 years of age.
A negative result indicates that HIV-1 DNA was not detected in the specimen (see Cautions). The lower limit of detection is 66 copies/mL.
Indeterminate results indicate that the presence or absence of HIV-1 DNA could not be determined with certainty after repeat testing of the clinical specimens in the laboratory, possibly due to PCR inhibition. Submission of a new specimen for testing is recommended.
Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
This assay should not be used as a screening test or a primary diagnostic test for HIV-1 infection except in infants of <2 years of age born to HIV-1-infected mothers.
This assay is optimized for the detection of group M subtypes (A to H) of HIV-1, but not groups N or O.
Diagnosis of HIV-1 infection should not rely solely upon the result of an HIV-1 proviral DNA assay. A positive result should be considered in conjunction with clinical presentation and additional established diagnostic tests prior to establishing a diagnosis. A negative result indicates only the absence of HIV-1 proviral DNA in the specimen tested and does not exclude the diagnosis of disease. Negative results should be interpreted with caution, considering the patient's risk factors for HIV infection, the analytical sensitivity of the assay (95% detection limit of 66 copies/mL), and genotype of the infecting HIV-1 strain. Follow-up testing is recommended for high-risk patients with initially negative test results.
Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.
Clinical References Provides recommendations for further in-depth reading of a clinical nature
1. DeSimone JA, Pomerantz RJ: New methods for the detection of HIV. Clin Lab Med 2002;22:573-592
2. Working Group on Antiretroviral Therapy and Medical Management of HIV-Infected Children. Guidelines for the use of antiretroviral agents in pediatric HIV infection. Available from URL: http://www.aidsinfo.nih.gov/ContentFiles/PediatricGL_SupIPDA.pdf 2005, pp 4-5