Examples of Helper virus in the following topics:
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- Therefore, it is a defective virus and cannot replicate without the help of hepatitis B virus.
- satellites (nucleic acid molecules with or without a capsid that require a helper virus for infection and reproduction)
- Satellites depend on co-infection of a host cell with a helper virus for productive multiplication.
- Their nucleic acids have substantially distinct nucleotide sequences from either their helper virus or host.
- Therefore, it is a defective virus and cannot replicate without the help of hepatitis B virus.
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- Human immunodeficiency virus infection / acquired immunodeficiency syndrome (HIV/AIDS), is a disease of the human immune system caused by infection with human immunodeficiency virus (HIV) .
- After the virus enters the body, there is a period of rapid viral replication, leading to an abundance of virus in the peripheral blood.
- During primary infection, the level of HIV may reach several million virus particles per milliliter of blood.
- This response is accompanied by a marked drop in the number of circulating CD4+ T cells, cells that are or will become helper T cells.
- Ultimately, HIV causes AIDS by depleting CD4+ T cells (helper T cells).
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- If a cell does not express these receptors then the virus cannot normally infect it.
- An example of this is the HIV virus, which exhibits tropism for CD4 related immune cells (e.g.
- T helper cells, macrophages or dendritic cells).
- These cells express a CD4 receptor, to which the HIV virus can bind, through the gp120 and gp41 proteins on its surface .
- In virology, Tissue tropism is the cells and tissues of a host that support growth of a particular virus or bacteria.
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- T helper cells assist the maturation of B cells and memory B cells while activating cytotoxic T cells and macrophages.
- Differentiation into helper T cell subtypes occurs during clonal selection following T cell activation of naive T cells.
- Cytotoxic T cells (TC cells, or CTLs) destroy virus-infected cells and tumor cells, and cause much of the damage in in transplant rejection and autoimmune diseases.
- Effector memory cells may be either CD4+ or CD8+, and produce either helper or cytotoxic T cells in a secondary immune response.
- T cells become activated upon encountering a pathogen and can become either cytoxic T or helper T cells.
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- CD4 cells or helper T cells provide protection against different pathogens.
- 1. activating antigen-specific cytotoxic T-lymphocytes that are able to induce apoptosis in body cells displaying epitopes of foreign antigen on their surface, such as virus-infected cells, cells with intracellular bacteria, and cancer cells displaying tumor antigens
- It is most effective in removing virus-infected cells, but also participates in defending against fungi, protozoans, cancers, and intracellular bacteria.
- CD4+ helper T cells recognize antigen in a complex with Class 2 major histocompatibility complex.
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- After a virus or bacteria enters a cell, it can no longer be detected by the humoral immune response.
- To do so, a T cell will become activated by interacting with an antigen of the infecting cell or virus presented on the MHC II of an APC.
- There are two main types of T cells: helper T lymphocytes (TH) and the cytotoxic T lymphocytes (TC).
- A helper T cell becomes activated by binding to an antigen presented by an APC via the MHCII receptor, causing it to release cytokines.
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- Antigen presentation stimulates T cells to become either "cytotoxic" CD8+ cells or "helper" CD4+ cells.
- Recognition of antigenic peptides through Class I by CTLs leads to the killing of the target cell, which is infected by virus, intracytoplasmic bacterium, or are otherwise damaged or dysfunctional.
- Exogenous antigens are usually displayed on MHC Class II molecules, which interact with CD4+ helper T cells.
- The antigen is processed and displayed on a MHC II molecule (3), which interacts with a T helper cell (4).
- In the lower pathway; whole foreign proteins are bound by membrane antibodies (5) and presented to B lymphocytes (6), which process (7) and present antigen on MHC II (8) to a previously activated T helper cell (10), spurring the production of antigen-specific antibodies (9).
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- Many interleukins are also considered lymphokines, interleukins released by helper T cells to organize immune responses.
- They can activate macrophages and natural killer (NK) cells to attack and lyse virus-infected cells.
- It is a protein released by NK cells, macrophages, and helper T cells, typically in systemic immune responses.
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- Patients with Human Immunodeficiency Virus (HIV) are particularly susceptible to opportunistic infections.
- HIV can develop into Acquired Immune Deficiency Syndrome (AIDS), which infects and destroys helper T cells (specifically CD4+ T cells).
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- In most cases, the sensitized B cell must then encounter a specific kind of T cell, called a helper T cell, before it is activated.
- This activation of the helper T cell occurs when a dendritic cell presents an antigen on its MHC II molecule, allowing the T cell to recognize it and mature.
- The helper T cell binds to the antigen-MHC class II complex and is induced to release cytokines that induce the B cell to divide rapidly, making thousands of identical (clonal) cells.
- A later encounter with the antigen, caused by a reinfection by the same bacteria or virus, will result in them dividing into a new population of plasma cells.