Chapter 6 Flashcards
What factors impact efficiency of aerosol transmission?
distance, humidity, and amount of ventilation
What physical and biochemical barriers are at the body surfaces?
skin, mucocilliary clearance, acid, bile, and proteolytic enzymes, natural inhibitors in fluids
What is a pattern recognition receptor?
sensor molecules that the innate immune system uses to detect pathogens
What is a pathogen associated molecular pattern?
Patterns that are displayed on the invading organism that PRRs recognize
What is a toll-like receptor?
a class of PRRs that detect a broad range of pathogens, including viruses
What is the significance of TLR and PAMP binding?
Binding of TLRs to their respective PAMP ligand results in a cell signal cascade that activates type 1 interferon and pro-inflammatory cytokines, key mediators of the innate and adaptive antiviral response
What is the significance of Type I interferons in the context of virus infections?
It is most pronounced in the local area where viral replication is occurring, rather than at distant sites. They are found in high concentrations in the mucus, for example during respiratory infections, and are considered to be a very important early defense mechanism to retard the progress of the infection sufficiently for other host defense mechanisms to have time to develop. Without interferon, many trivial infections would undoubtedly be rendered lethal.
What is the role of ligands binding to TLR in the elicitation of fever?
Ligands bind to TLR causing the release of pro-inflammatory cytokines which exert antiviral activity (fever)
Give one example of how fever can limit viral pathogenesis.
Possible examples:
Inhibition of virus replication, dilation of blood vessels, increased blood flow to affected areas, increased rate of inflammatory response
List the three main mechanisms of how antibodies defend against viral infections.
Neutralization, opsonization, and antibody-dependent cell mediated cytotoxicty
What two mechanisms can antibody use to block infection by preventing attachment, penetration, or uncoating?
Steric hindrance - antibody physically interferes with virus attachment to receptors
Prevention of penetration by blocking the function of the fusion protein
How does opsonization work in the context of inactivation of viruses?
It assists the macrophages in ingesting foreign material so that it can be cleared; particularly important for small, non-cell associated viruses
What is antibody-dependent enhancement of infectivity?
some viruses that replicate in macrophages use this mechanism to enter target cells, a process that can lead to antibody-dependent enhancement of infectivity
How does humoral immunity play a role in antiviral defenses?
it is most important in prevention of initial entry of a virus
How does cell mediated immunity play a role in antiviral defenses?
it exerts its greatest influence in controlling the spread of viruses, particularly cell-associated viruses once they gain entry; recovery from established virus infections
