Hiv infection, hiv coreceptor tropism

Synonym(s)

Coreceptor tropism; Coreceptor Tropism

General information
This section has been translated automatically.

Besides CD4 receptors, HI viruses require the interaction of the viral envelope protein with secondary cellular receptors on the surface of target cells. These interactions trigger the membrane fusion of the membranes of the HI virus with the membrane of the target cell. In vivo, the core receptors CCR5 and CXCR4 are of particular importance. They are each named after their natural ligands. For the core receptor CCR5 the ligands are CC-chemokines (MIP) and RANTES, for the CXCR4 core receptor it is the CXC-chemokine SDF-1. HIV strains are called R5 strains if they use CCR5 receptors to enter the cell, or X4 strains if they attack the cell via CXCR4 receptors. Dualtrope strains are therefore HIV strains that can use both core receptors to infect a host cell. They are known as D/M strains.
R5 strains preferentially attack activated CD4 cells and macrophages. X4 strains also attack naive and dormant T cells.
Pure X4 strains are rarely observed so far, mainly R5 strains have been described, less frequently also dualtrope HIV strains. According to the results of the study, it can be assumed that approx. 80-90% of patients undergoing therapy have R5 strains.
The change of tropism from R5 or D/M to X4 is often associated with strongly reduced CD4 cell counts and disease progression. Plasma viremia, on the other hand, is similarly high in D/M strains and R5 strains.
In HIV patients with therapy experience, the proportion of R5 strains is 50-60%, therefore a tropism test should be performed before therapy with entry inhibitors.
Patients with non-progressive HIV disease predominantly show R5 virus strains.