Lecture 18 10/24/23 Flashcards
What are the general characteristics of viruses?
-microscopic infectious agent
-smaller and simpler than the cell
-obligate intracellular
What are the components of virus structure?
-DNA or RNA
-capsid
-envelope (optional)
-surface proteins
What do virus-receptor interactions play a regulatory role in?
-viral host range
-tissue tropism
-viral pathogenesis
What are the innate immune responses to viral infection?
-IFN-gamma
-natural killer cells
What are the adaptive immune responses to viral infection?
-antibodies
-cytotoxic T cells
What characteristics of viruses allow them to “fight back” against the immune system?
-obligate intracellular
-hiding
-release of suppressive cytokines called virokines
-targeting lymphoid cells
What two adverse events can result from viruses fighting back?
-death of important cells
-deposition of antigen-antibody complexes
Where are antigen-antibody complexes deposited in canine adenovirus infections?
eyes and kidneys
What is antigenic shift?
sudden appearance of new influenza strains to which the population his little/no preexisting immunity
What is caused by antigenic shift?
widespread disease outbreaks/pandemics
What is antigenic drift?
minor and gradual changes in the genes encoding the HA and NA surface proteins
What is caused by antigenic drift?
-seasonal flu outbreaks
-need to update yearly flu vaccine
What are other potential mechanisms for viruses to evade the immune system?
-inhibition of host’s type I IFN response
-inhibition of class I MHC
-inhibition of NK cells
How does hepatitis B virus trick the immune system?
by releasing a multitude of surface proteins; antibodies bind to the free surface proteins instead of the virus
What is unique about canine distemper virus?
ability to replicate within immune cells and spread throughout entire body
