The Early Host Response: Cell-Autonomous and Innate immunity Flashcards
The immediate response to an infection is based on
two coupled processes: detection and alarm.
Microbes contain unique components, including certain
carbohydrates, nucleic acids, and proteins, that are
recognized by cellular pattern recognition receptors
present either on the cell surface or in the cytoplasm.
Binding of a particular ligand to a pattern recognition
receptor initiates a signal transduction cascade that
results in activation of cytoplasmic transcription regulatory
proteins
What are examples of these proteins?
Nf-kb
IFN
This innate immune response is crucial in antiviral
defense because it can be activated quickly, functioning
within minutes to hours of infection
What is the function of phagocytes as part of innate immunity?
Phagocytes gather information and initiate the host
immune response by taking up cellular debris and
extracellular proteins released from dying or apoptosing
cells.
Cell is infected by a virus produces IFN
What are possible changes in the cell that can occur to tackle the infection?
apoptosis - a normal biological process, but can be induced by a viral infection. Viruses such as CMV inhibit cellular apoptosis
autophagy - remove damaged parts of cell by using lysosomes
epigenetic silencing
RNA interference
What is epigenetic silencing in a virally infected cell
Epigenetic silencing is a natural phenomenon in which the expression of genes is regulated through modifications of DNA, RNA, or histone proteins.
It is a mechanism for defending host genomes against the effects of transposable elements and viral infection
Example - IFN may trigger suppression of RNA production to make ribosomes, to help reduce viral reproduction
What is a PAMP?
Pathogen-associated molecular pattern
Usually unique bacterial/ fungal carbohydrates, proteins or nucleic acids
Toll-like receptors are the most basic pattern recognition receptors, which recognise PAMPs. Primarily found on dendritic cells/ macrophages
What is meant by cytopathic effect?
Damage to cells caused by a virus, or due to changes in the cell because of the virus
e.g viral proteins may induce alterations in cell integrity, causing release of intracellular components
What does CRISPR stand for?
clustered regularly interspaced short palindromic repeats
short repetitions of nucleotide sequences in most bacterial and archael genomes
CRISPRs are associated with cas genes
What is the role of CRISPR/Cas system?
confers prokaryotic resistance to foreign genetic elements such as bacteriophages
CRISPR/Cas system includes an RNA-guided DNA endonucelase Cas9 to generate double-strand breaks in invasive DNA, during bacterial immune response
Are the effects of IFN considered intrinsic or innate immunity?
IFN released from infected cells can bind to receptors on adjacent uninfected cells, warning of potential impending viral infection
innate immunity for infected cells
intrinsic immunity for uninfected cells
What is meant by the term soluble effector protein
also known as cytokines, neurotransmitters and hormones
different names, describing proteins in blood having effects
During viral infection, what are the first cytokines to be produced?
IFN
TNF-alpha
IL-6
IL-12
What are examples of virus modulations of the IFN reponse?
Inhibit IFN synthesis - EBV/ Vaccinia
IFN receptor decoys - Vaccinia
Inhibition of IFN signalling - Vaccinia, adenovirus, HCV
Block function of IFN-induced proteins - adenovirus, HIV, HBV, influenza
Complement is part of innate defense. It was named as it complemented antibodies in lysing bacteria
What are the main functions of complement?
Lysis of bacteria
Opsonisation - enable phagocytosis
Activation of inflammation - recruit other immune cells
Solubilisation of immune complex - virus-immune complexes can accumulate in lymphoid organs and kidney. Complement disrupts these complexes enabling them to be cleared
