This test
is used primarily to diagnose HIV infection in infants born to HIV
infected mother and is a qualitative assays for
proviral
HIV-1 DNA which is the form of the virus capable of being
integrated into the host genome. These forms of the virus (proviral
forms) are found in only a small fraction of peripheral blood
mononuclear cells (PBMC) from infected individuals but they can
amplified and usually be detected by PCR.
Therefore, a diagnosis of
HIV-1 infection can also be made by demonstrating the presence of
proviral DNA in PBMC. Assays for detecting proviral DNA employ the
polymerase chain reaction (PCR) to amplify conserved sequences in
sections the HIV-1 gene. Experienced laboratories can achieve 100%
sensitivity and specificity in PCR testing for HIV-1 DNA. The
sensitivity of HIV-1 DNA PCR assays in clinical practice is 96-99%,
however. Strict attention to guard against contamination from the carry
over of PCR products is essential to prevent false-positive results.
As with virus culture and
p24 antigen detection, sensitivity is lower in individuals with higher
CD4+ cell counts due to the lower titer of circulating infected PBMC.
DNA PCR assays for HIV-1 are used most often in the early diagnosis of
HIV-1 infection in neonates. Clinical applications of these tests are
relatively limited in adults, but occasionally DNA PCR testing may be
helpful in resolving indeterminate western blots in high-risk
individuals.
