Point-of-care (POC) testing is medical testing that is performed outside of a lab setting. POC testing can be done bedside, at home, remotely and with rapid-diagnostics. POC testing may be carried out by first responders, nurses, clinicians, doctors, and dependent on their usability, the individuals themselves. POC testing can be done with using different specimens, based on the test itself. Specimens include whole blood, serum, plasma, oral fluid and other body fluids.
HIV POC assays are tests which can detect the presence of HIV infection.
When individuals are infected with HIV, their body produces antibodies to proteins in the HIV virus. The presence of these antibodies in various body fluids, including blood and oral fluid, are indicative of exposure to the HIV virus. There are, however, situations where HIV antibodies may be absent even though an infection is present. The development of antibodies to HIV (i.e. “seroconversion”) in a person exposed to the virus may take several weeks to months, during which time the person may be infected and capable of transmitting the virus. Conversely, the presence of HIV antibodies in neonates may reflect acquisition of maternal antibodies as opposed to HIV infection of the infant.
After the specimen has been collected according to the instructions and mixed with the Sample Buffer, the specimen/Sample Buffer mixture is absorbed into the absorbent pad at the end of the Test Strip. The liquid mixture continues to migrate up the Test Strip by a wicking action, until it encounters a dehydrated reagent conjugate which is rehydrated by the liquid. The reagent turns reddish-purple in color which is used later in the Test Strip to visualize the results. Specific proteins will bind to both positive (if any) and negative antibodies that may be present in the liquid containing the specimen.
The liquid continues to wick up the strip onto a nitrocellulose membrane. Once the liquid starts to appear on the membrane, the user will see a reddish-purple cloud migrate up the strip with the liquid. The liquid will continue to be drawn up to the top of the strip until the reddish-purple cloud on the membrane has cleared 20 minutes after the start of the test.
As the liquid containing antibodies bound to the conjugate crosses the membrane, it encounters the invisible reagent lines where the results are read.
The color intensity of the lines does not necessarily correlate to the amount of antibody captured or to the severity of the infection, if present. The results of the test are interpreted in the time frame noted in the product insert after adding the Test Strip to the Sample Buffer containing the specimen. At this time, the antibodies in the specimen will have had adequate time to migrate up the entire strip. A reddish-purple line will form indicative of the presence of antibodies, the test has been performed correctly, and/or the specimen is one with a recent or long term infection.
- The Asanté ® assays must be used according to the instructions in the product insert to obtain accurate results.
- Results must be read in the time frame stated in the product insert after inserting the Test Strip into the specimen / Sample Buffer mixture.
- The tests are intended for use only with sample types outlined in the product insert. Alternate collection methods or sample types may yield erroneous results and should not be used.
- Individuals infected with the virus but who are on therapeutic medications may produce false negative results.
- Confirmation of test results should be obtained using an approved test algorithm.
- The intensity of any line does not necessarily correlate with the levels of any antibodies that may be present or with the severity of disease, if present.
- A non-reactive result does not exclude the possibility of exposure to the virus or the presence of viral infection. Antibody response to recent viral exposure may take several weeks to several months to reach detectable levels.
- The presence of antibodies is presumed to be an indication of a viral infection. However, individuals who have participated in specific vaccine studies may have antibodies presented as a result of vaccination, but may not be infected.
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