Introduction to Viruses Flashcards
-What 3 structures can viruses take?
- icosahedral( 20 faces, each of which is an equilateral triangle)
- Helical (protein binds around DNA/RNA in a helical fashion
- Complex (neither icosahedral or helical)
What is meant by viruses being obligate intracellular pathogens?
Can only replicate inside host cell
What is meant by tissue tropism?
most viruses have a specific host range and only infect specific host cell types
How can virus families be classified? (4)
- virion shape/symmetry
- presence/absence of envelope
- genome structure
- mode of replication
What structures make up a virion? (5)
- lipid envelope
- nucleic acid
- spike projections
- virion associated polymerase
- protein capsid
What steps are involved in virus replication? (7)
- attachment
- uncoating
- replication of genomic nucleic acid
- protein synthesis
- virion assembly
- budding and release
- maturation
How can viruses be transmitted? (9)
- blood-borne
- sexual
- vertical
- faecal-oral
- droplet
- airborne
- close contact
- vector-borne
- zoonotic
What is the host range for smallpox and measles?
only infect humans
What can coinfection of human and animal/bird strain in one organism lead to?
recombination and generation of a new strain
What are 4 consequences of viral infection?
- clearance of virus (with no,short or long term immunity)
- chronic infection
- latent infection
- transformation (long term infection with altered cellular gene expression)
What kind of immunity is involved in hepatitis C?
no lasting immunity
What kind of immunity is involved in measles?
long term immunity
Give 3 examples of chronic infections
- HIV
- hepatitis B
- hepatitis C
Give 2 examples of viruses which exhibit transformation .
- Epstein-Barr Virus
- Human Papillomavirus
