Laboratory Diagnosis of HIV Infection

HIV Markers During Early Infection

October 2009

First, let’s review the virologic and serologic course of an individual who is infected with HIV. Here, from this graph, you see that the first marker that becomes detectable after infection is the HIV RNA, indicated by the green line. This is detectable by current molecular methods at about 11 days from the time of infection or exposure to HIV.

The second marker that becomes detectable in the laboratory is the HIV p24 antigen, indicated in the purple line. This is detectable by day 16 from exposure. And finally, the HIV antibodies that are detectable by current commercial assays occur at about day 22 from the date of infection. So the most widely used serologic tests, which are HIV antibody screening tests, are actually the least sensitive in picking up HIV infection compared to the other 2 markers.

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Jump to section:

• Introduction
• HIV Markers During Early Infection
• Assay-Defined HIV Detection Windows and Infection Periods
• Serologic Tests for HIV Infection in US
• Principle of Future Combined HIV Antigen-Antibody ELISAs
• Virology Tests for HIV Infection
• HIV Serologic Screening Algorithm
• HIV Rapid Serology Follow-up Algorithm
• Indeterminate HIV-1 Antibody Western Blot Results
• Rapid HIV Antibody Tests Licensed in US, 2009
• Predictive Value: Single Screening Test
• Rapid HIV Antibody Tests: Clinical Applications
• Follow-Up Testing of Reactive Rapid HIV-1 Antibody Tests Results
• Diagnostic HIV Testing in Infants
• Diagnostic HIV Testing in Infants
• Awareness of Serostatus Among People with HIV and Estimates of Transmission in US
• Reasons for Testing: Late vs. Early Testers
• 2006 US CDC Recommendations: Adults and Adolescents
• 2006 US CDC Recommendations: Adults and Adolescents
• 2006 US CDC Recommendations: Pregnant Women
• 2006 US CDC Recommendations: Pregnant Women
• Summary
• Questions?
• Disclosure