text: Most HIV-based co-receptor research focuses on the CCR5 co-receptor. The majority of HIV strains use the CCR5 receptor. HIV-2 strains can also use the CXCR4 receptor though the CCR5 receptor is the more predominantly targeted of the two.
  Both the CCR5 and the CXCR4 co-receptors are seven-trans-membrane (7TM) G protein-coupled receptors.
  Different strains of HIV work on different co-receptors, although the virus can switch to utilizing other co-receptors. For example, R5X4 receptors can become the dominant HIV co-receptor target in main strains. HIV-1 and HIV-2 can both use the CCR8 co-receptor. The crossover of co-receptor targets for different strains and the ability for the strains to switch from their dominant co-receptor can impede clinical treatment of HIV. Treatments such as WR321 mAb can inhibit some strains of CCR5 HIV-1, preventing cell infection. The mAb causes the release of HIV-1-inhibitory b-chemokines, preventing other cells from becoming infected.