Seroconversion And Viral Markers

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Seroconversion is the transition from seronegativity for a pathogen, here HIV, to a state of seropositivity. She signs the infection. The body and its immune system were exposed to the virus and reacted by secreting specific antibodies.

Seroconversion principle

Understanding how and with what temporality HIV reports its presence in the blood makes it possible to understand the different waiting times before carrying out a test according to the screening technique used.

the appearance of plasma anti-HIV antibodies

Seroconversion period or serological window, the period between HIV contamination and the appearance of plasma anti-HIV antibodies (that is, present in the blood) manufactured by the body. This period is between two and five weeks.

The kinetics of the markers of HIV infection

>After contamination (D0), HIV multiplies silently in the body for about ten days. No examination can then detect it.
> From the tenth day (D10), the HIV becomes detectable by PCR or by measuring the viral load.
From the second week (D14-D15), the p24 HIV protein or p24 antigen becomes detectable by the p24 antigenemia or the combined Elisa test.
> From the third week on average (from two to five), anti-HIV antibodies become detectable in turn.

ELISA tests

Currently available Elisa tests, so-called fourth-generation combination tests, detect both p24 protein and anti-HIV1 and anti-HIV2 antibodies.
Rapid tests and self-tests detect anti-HIV1 and anti-HIV2 antibodies but not p24 antigen.

Elisa/Western Blot

The search for anti-HIV antibodies is performed by an Elisa test. NATrol molecular control Panel for IVD for HIV When this test is positive, it must always be confirmed by another technique called Western Blot. These two tests are complementary.

The rescreening

However, the immune response is variable among individuals and antibodies may sometimes appear later. Therefore, to be able to say that a person is not infected with HIV, a new screening test must be done three months after the last exposure. This period should be accompanied by psychological support and, if necessary, social support and prevention counseling.

the Nattrol tests

In the case where prophylactic treatment has been prescribed, the immune response is likely to be delayed by treatment. This will be taken into account during the control tests (Nattrol) to check whether or not the person being treated is infected with HIV.