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Is a DNA PCR test reliable for HIV testing?
Question
Is a negative result obtained from a HIV DNA PCR test result, wherein the sample is given 72 hours post exposure, a true & conclusive negative? What is the right time to give a sample for HIV testing after suspected exposure?
Expert Answer
P
Dr Pradeep SethApr 25, 2007
Professor of Virology and Head, Department of Microbiology,
and In-charge HIV/AIDS Reference Centre (NACO),
A.I.I.M.S., New Delhi
and In-charge HIV/AIDS Reference Centre (NACO),
A.I.I.M.S., New Delhi
No. The HIV RNA appears in blood around 15 days post exposure depending upon the replication profile of the virus strain. Therefore, blood samples should be tested regularly after exposure: 2 weeks; 4 weeks; 6 weeks; 8 weeks; 10 weeks and 12 weeks. Samples should be tested for the presence of HIV proviral DNA in the peripheral blood lymphocytes by polymerase chain reaction, particularly Real-time PCR assay from an accredited laboratory. Looking for HIV RNA in plasma during window period is less sensitive. Samples collected after 6 weeks post-exposure should first be tested for the presence of HIV antibodies. If positive, it will indicate HIV infection.
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