HIV 2 is also a p24 antigen

HIV test (HIV-1 and HIV-2 + p24 antigen)


Notes on the sensitivity of the diagnosis, Source:

The diagnosis of HIV infection is based on the detection of specific antibodies in combination with the detection of virus antigens or viral nucleic acids (two-stage diagnosis with search and confirmation test) (Opinion of the Joint Diagnostic Commission of the DVV and the GfV 2015: Bundesgesundheitsbl 2015 · 58: 877– 886; DOI 10.1007 / s00103-015-2174 -x: pdf).

Specific antibodies are detectable on average after 22 days in an infected person and virus antigen after 16-18 days. Viral nucleic acids can be diagnosed on average after 11 days.

If modern 4th generation addiction tests are used, which in addition to antibodies also detect HIV antigens, reliable detection is usually possible after a maximum of 6 weeks. This also means that 6 weeks after possible exposure, an infection can be ruled out with a high degree of certainty due to a negative result in the 4th generation HIV antibody / antigen search test (no specific antibodies or p24 antigen detectable).

In the first step of the two-stage diagnosis, a highly sensitive test, e.g. an ELISA or a comparable test, is used to check whether antibodies against viral antigens and / or viral p24 antigen are present.

Most of the ELISAs used in Germany can recognize HIV-1 and HIV-2-specific antibodies at the same time. In rare cases, the search test can lead to unspecific reactions. Therefore, the specificity of the binding of the antibodies to the viral proteins (antigens) is checked with a second, highly specific test, the so-called immunoblot.

As an alternative to confirmation in the immunoblot, a reactive search test can also be confirmed by detecting viral nucleic acids in a NAT, e.g. with the polymerase chain reaction (PCR), provided that the measured viral load is at least 1,000 copies / ml.

Even if NATs are used to confirm a reactive search test, testing a second sample is recommended to rule out sample mix-up.

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