L09-Viruses Flashcards
In general terms what is the main response of the innate immune system to viral infection?
Type 1 interferons (IFN alpha and IFN beta) limit the infection within the tissues.
What are viruses?
Obligate intracellular parasites
Have no metabolic activity outside of host cell so cannot be considered alive.
basically is a nucleic acid genome contained within a protein shell.
How are viruses classified and what 4 questions can be asked to classify these viruses into groups?
They are classified into 7 groups
- Is the genome DNA?
- Is the genome double stranded?
- Is the the RNA genome sense (like mRNA) or antisense?
- Does it use reverse transcriptase?
What are the physical appearances of viruses?
They often form regular geometrical shapes
How do viruses replicate?
They must be within a susceptible host cell. The capsid is dissembled and the virus starts to direct the cell to synthesise new viral components.
What are the three types of viral components that are synthesised for replication?
1) the essential replication factors (DNA or RNA)
2) The structual proteins that are assembled to form new capsids
3) copies of the viral genome that are packaged inside the new genome
What is a virus receptor?
A receptor on the surface of a cell that is required for the virus to bind to that cell and infect it. This defines which organs and species are targeted by the virus.
What disruption to the host do viruses cause?
They either completely destroy the cell by lysis when releasing viruses or can bud off from the cytoplasm. The complete destruction are the most pathogenic viruses
How are viruses identified in the laboratory?
They were initially grown in culture and then identified by their distinct plaque formation however this was very slow so useless diagnostically. Now they use ELISA methods through detecting antigens on the virus.
Virus detection can also be done by PCRs using primers for the viruses, this is now the main method that is used.
