R5viruksia

R5viruksia, also known as R5 viruses or R5-tropic viruses, are a subgroup of human immunodeficiency virus type 1 (HIV-1). Their defining characteristic is their tropism, meaning their preference for infecting specific cell types. R5 viruses primarily utilize the CCR5 coreceptor on the surface of host cells to gain entry. This is in contrast to R4 viruses (also known as X4 viruses), which primarily use the CXCR4 coreceptor.

Initially, most HIV-1 infections are established by R5 viruses. These viruses are typically found in the gut-associated lymphoid tissue and are efficient at establishing initial infection and spreading through the body. The CCR5 coreceptor is abundant on the surface of macrophages and memory T cells, which are key targets for R5 virus entry.

Over time, in some individuals, HIV-1 can undergo a tropism switch. This means the virus can evolve to use the CXCR4 coreceptor in addition to or instead of CCR5, becoming an R4 virus or a dual-tropic virus. R4 viruses tend to infect and replicate more efficiently in activated T cells and are associated with faster disease progression and a higher viral load. The tropism switch is often linked to the later stages of HIV infection, known as acquired immunodeficiency syndrome (AIDS).

Understanding viral tropism is important in HIV treatment and management. Certain antiretroviral drugs, known as CCR5 antagonists, specifically target the CCR5 coreceptor and are effective against R5-tropic HIV. However, these drugs are not effective against R4-tropic viruses, making tropism testing a crucial step in determining the most appropriate treatment regimen for an individual with HIV.