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The entry of enveloped viruses into cells also triggers an antiviral response. Explain this response.
It is non-specific. Instead of producing cytokines, interferon-stimulated genes are produced that encode intracellular proteins that block virus transcription and translation
- an intrinsic cellular process that increases cell survival during periods of stress
- stressed cells degrade their contents by forming phagosomes.
RIG-I and MDA5
recognize RNAs from different viruses, with the recognition depending on both RNA structure and length
RIG-I recognizes short dsRNA and ssRNA
MDA5 recognizes long dsRNA
What is the signal transduction pathway that occurs when viral components are recognized?
viral proteins or NA bind to TLRs--> MyD88 and TRIF
- All TLRs except TLR-3 interact with MyD88
- TLR-3 interacts with TRIF
Through a series of associations, protein kinases are recruited, which leads to the NF-kappaB signal transduction cascade, which translocates into the nucleus and activates cytokines
Explain the activity of perforin.
makes holes in the cell surface membrane as well as intracellular membranes, facilitating the entry of a second cytotoxic protein, granzyme B, which cativates apoptosis
Granzyme B activates both caspase-3 and the pathway leading to release of mitochondrial proteins and the formation of the apoptosome
clonal selection theory
antigen-specific cells of the imune system with a great variety of binding specificities are created in an antigen-independent manner in the bone marrow
these naive B and T cells are then selected and acivated upon contact with antigens in the lymph nodes or spleen to generate the immune response
What are antigen presenting cells?
- dendritic cells
- B cells
How are Tc cells prouced?
by an encounter between an antigen presentingg cell adn a naive CD8 positive T cell