What is R5 strain of HIV?
R5 strains are most frequently transmitted during primary HIV-1 infection and persist throughout the course of infection, while expanded coreceptor usage and evolution to T-tropic viruses are closely linked with disease progression (51).
What is X4 tropic HIV?
Approximately 50% of late-stage HIV patients develop CXCR4-tropic (X4) virus in addition to CCR5-tropic (R5) virus. X4 emergence occurs with a sharp decline in CD4+ T cell counts and accelerated time to AIDS. Why this phenotypic switch to X4 occurs is not well understood.
What is X4 virus?
X4-tropic virus, also known as T-tropic virus, is associated with more pronounced depletion of CD4 T cells than R5 virus. CXCR4 is expressed on nearly all CD4 T cells whereas only 15-30% express CCR5. Therefore, X4 virus has a wider range of susceptible target cells.
Why is the X4 strain of HIV called X4?
The alpha-chemokine SDF-1, a ligand for CXCR4, suppresses replication of T-tropic HIV-1 isolates. It does this by downregulating the expression of CXCR4 on the surface of these cells. Viruses that use only the CCR5 receptor are termed R5, those that only use CXCR4 are termed X4, and those that use both, X4R5.
What are R5 viruses?
HIV/AIDS Glossary A strain of HIV that enters and infects a host CD4 cell by attaching to the CCR5 coreceptor on the CD4 cell.
What is the R5 mutation?
A new classification for HIV-1 As mentioned CCR5-using HIV-1 variants are called R5, whereas CXCR4 using HIV-1 variants are called X4; variants that use both co-receptors are called R5X4.
What is x4 strain?
HIV/AIDS Glossary A strain of HIV that enters and infects a host CD4 cell by attaching to the CXCR4 coreceptor on the CD4 cell.
Is T-cell same as CD4?
A CD4 count is a test that measures the number of CD4 cells in your blood. CD4 cells, also known as T cells, are white blood cells that fight infection and play an important role in your immune system.
What is CCR5 tropic hiv1?
HIV is usually R5-tropic (uses CCR5) during the early stages of infection, but the virus may later switch to using either only CXCR4 (X4-tropic) or both CCR5 and CXCR4 (dual-tropic). An HIV drug called a CCR5 inhibitor blocks HIV from attaching to the CCR5 coreceptor, which prevents HIV entry into the CD4 cell.
What are r5 viruses?
What does CD4 and CD8 stand for?
CD4 and CD8 are two types of white blood cells in your blood. CD4 cells are also called T-helper cells, T-suppressor cells, and cytotoxic T-cells. They help the body fight infections. CD8 cells are also called cytotoxic T-lymphocytes.
What do T4 cells do?
The primary role of T4-lymphocytes is to regulate the body’s immune responses through the production of cytokines. T4-lymphocytes display CD4 molecules and T-cell receptors (TCRs) on their surface.
Are CCR5 and CXCR4 related?
The chemokine receptors CXCR4 and CCR5 function as coreceptors for HIV-1 entry into CD4+ cells. During the early stages of HIV infection, viral isolates tend to use CCR5 for viral entry, while later isolates tend to use CXCR4.
What is the difference between HIV R5 and HIV X4?
R5 and X4 HIV isolates are both transmitted but, in most cases, R5 viruses predominate in the blood prior to the development of AIDS-related pathogenesis. The reason for the selective growth of the R5 strain is not known, but could reflect a replication advantage of R5 viruses over X4 viruses in CD4+ cells.
What is x4 HIV tropism?
HIV tropism. Viruses that use only the CCR5 receptor are termed R5, those that only use CXCR4 are termed X4, and those that use both, X4R5. However, the use of a coreceptor alone does not explain viral tropism, as not all R5 viruses are able to use CCR5 on macrophages for a productive infection.
What is the difference between R5 and X4 co-receptor?
The results show whether the patient is infected with virus that enters cells using the R5 co-receptor, the X4 co-receptor, or both (dual/mixed). Patients with strains of HIV that prefer the R5 receptor tend to remain healthy longer than those with the strains that prefer X4.
What is an X4 virus?
These strains are now called X4 viruses. The alpha-chemokine SDF-1, a ligand for CXCR4, suppresses replication of T-tropic HIV-1 isolates. It does this by downregulating the expression of CXCR4 on the surface of these cells.