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PCR
assays
Qualitative
assays for proviral HIV-1 DNA. Although
only a small fraction of peripheral blood mononuclear cells (PBMC)
from infected individuals carry proviral HIV-1 DNA, they can usually
be detected by PCR. Therefore, a diagnosis of HIV-1 infection can
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 the HIV-1 gag or pol gene.
Experienced laboratories can achieve 100% sensitivity and specificity
in PCR testing for HIV-1 DNA (37). The
sensitivity of HIV-1 DNA PCR assays in clinical practice is only
96-99%, however (38-41). 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.
4/15/01
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by HIV and Hepatitis.com. All Rights Reserved
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