What does tropism mean in HIV?
HIV tropism refers to the cell type in which the human immunodeficiency virus (HIV) infects and replicates. HIV tropism of a patient’s virus is measured by the Trofile assay.
Does HIV display cellular tropism?
The cellular tropism of HIV is largely determined by the cell surface receptors it uses for binding and entry. HIV infects and eventually destroys T-helper lymphocytes but not T-killer lymphocytes, because the T-helper cells express CD4 whereas the cytotoxic T-cells express CD8.
What receptors determine the tropism of HIV for human cells?
The envelope gene of human immunodeficiency virus type 1 (HIV-1) determines the cell tropism of the virus (11, 32, 47, 62), the use of chemokine receptors as cofactors for viral entry (4, 17), and the ability of the virus to induce syncytia in infected cells (55, 60).
What is selective tropism?
Synonym(s) Tropism. When HIV selectively attaches to a particular coreceptor on the surface of a host CD4 cell. HIV can attach to either the CCR5 coreceptor (R5-tropic) or the CXCR4 coreceptor (X4-tropic) or both (dual-tropic). Related Term(s)
What is an example of tropism?
Phototropism. You might have noticed that plants bend toward the light. This is an example of a tropism where light is the stimulus, known as phototropism (Figure below). To obtain more light for photosynthesis, leaves and stems grow toward the light.
What is this tropism?
tropism, response or orientation of a plant or certain lower animals to a stimulus that acts with greater intensity from one direction than another.
What is R5 tropic virus?
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 tropism in molecular biology?
The capability of a virus to infect a distinct group of cells in the host is referred to astropism. For many viruses, tropism is determined by the availability of virus receptors on the surface of a host cell.
What is tropism and examples?
Growth toward or away from a stimulus is known as a tropism. You might have noticed that plants bend toward the light. This is an example of a tropism where light is the stimulus, known as phototropism (Figure below). To obtain more light for photosynthesis, leaves and stems grow toward the light.
What causes tropism?
Environmental factors, including light, chemical nutrients, water, and gravity are stimuli that can provoke tropisms in a plant. The plant grows in the direction of the stimulus as hormones inside the stem, root, and leaf systems in a plant aid in the elongation and growth process of the plant toward the stimuli.
What is x4 tropic virus?
A strain of HIV that enters and infects a host CD4 cell by attaching to the CXCR4 coreceptor on the CD4 cell.
What is a dual tropic virus?
A strain of HIV that can enter and infect a host CD4 cell by attaching to either the CCR5 or CXCR4 coreceptor on the CD4 T lymphocyte (CD4 cell).
What is infection tropism?
What are the 3 tropism?
Summary. Tropisms are growth toward or away from a stimulus. Types of tropisms include gravitropism (gravity), phototropism (light), and thigmotropism (touch).
What is CCR5 and CXCR4?
CXCR4 is the fusogenic receptor that promotes entry of T-tropic HIV-1 strains, while CCR5 allows entry of M-tropic HIV-1 strains (13–20). The importance of these findings recently has been underscored by the finding that individuals deficient in CCR5 remain uninfected in the face of high-risk exposure to virus (22–24).
What is tropism assay?
Tropism assays are used to determine co-receptor usage of HIV-1 in patients who may be candidates for treatment with CCR5 antagonists. Phenotypic assays are used most often in the clinical trials of CCR5 antagonists, and are considered the “gold standard” for comparison to other methods of tropism testing.
What are the three types of tropism?
While there are several forms of tropism, we’ll just focus on three key types: phototropism, geotropism and thigmatropism.
What drugs are CCR5 antagonist?
The current leading CCR5 antagonists in clinical development include maraviroc (UK-427,857, Pfizer), aplaviroc (873140, GlaxoSmithKline) and vicriviroc (SCH-D, Schering-Plough), which have demonstrated efficacy and tolerability in HIV-infected patients.
What is the function of CCR5?
The CC chemokine receptor 5 (CCR5) is responsible for immune and inflammatory responses by mediation of chemotactic activity in leukocytes, although it is expressed on different cell types. It has been shown to act as co-receptor for the human and simian immunodeficiency viruses (HIV-1, HIV-2, and SIV).
What is viral tropism assay?
What does a CCR5 antagonist do?
HIV/AIDS Glossary
CCR5 antagonists block the CCR5 coreceptor on the surface of certain immune cells, such as CD4 T lymphocytes (CD4 cells). This prevents HIV from entering the cell.
What is CCR5 used for?
CCR5 is a co-receptor used by HIV in early-stage infection (Scarlatti et al., 1997), and mutation of CCR5 (CCR5Δ32) is known to confer resistance to HIV infection (Huang et al., 1996; Liu et al., 1996; Samson et al., 1996).
What is CD4 and CCR5?
The association of CD4, a glycoprotein involved in T cell development and antigen recognition, and CCR5, a chemotactic G protein-coupled receptor, which regulates trafficking and effector functions of immune cells, forms the main receptor for the human immunodeficiency virus HIV.
What drug is a CCR5 antagonist?
The CCR5 antagonist maraviroc is FDA-approved for treatment-experienced patients with R5 virus (only), and no patient should receive maraviroc without first undergoing a tropism assay.
What drugs are INSTIs?
Integrase strand transfer inhibitors (INSTIs) are oral antiretroviral agents used against HIV infection. There are three agents available, including raltegravir, elvitegravir and dolutegravir, some of which are available as combination medications with other antiretroviral drugs.