Virology Exam 3a Flashcards
How is a virus detected?
host cells sense virus with toll-like receptors
- initial connection triggers production of cytokines (interleukin)
- entry triggers interferon-stimulated genes
What do toll-like receptors recognize?
- virus proteins
- nucleic acids
- pathogen associated molecular patterns (PAMPs)
cellular response to viral infection
virus recognition leads to production of cytokines
What do cytokines do?
stimulate protective reactions in infected host
- interferons
- pro-inflammatory
- chemokines
- anti-inflammatory cytokines
interferons
major players in host defense against most viruses, effects replication
- protect nearby cells against viral infection by letting know there is a virus present
pro-inflammatory
cytokines, activate immune cells in circulatory system
- effect immune response
chemokines
recruit other immune cells to sire of infection, attractants
- effect immune response
anti-inflammatory cytokines
suppress pro-inflammatory sytokines
- effect immune response
first line of defense against virus
- interferons
- can trigger the death of the infected cells
- apoptosis involves activation of caspases
How many different kinds of interferons are there?
4: alpha, beta, gamma and lambda
- made by different cells
- bind to different receptors
- have distinct functions
What mechanisms do viruses use to avoid interferons?
- inhibition of PKR activity
- inhibition of production and activity of interferon
- interfere with signaling pathways
What is used to combat virus infections in plants and invertebrates?
RNAi
RNAi process
- RNAi is initiated by dsRNA-sepcific ribonuclease III enzyme DICER
- cleaves dsRNA into siRNAs which are bound to RISC
- RISC cleaves complementary RNA
microRNA
- used to control gene expression
- inhibit translation or degrade mRNA
