Virology 1 Flashcards
Definition of viruses
small infectious particles
consist of either DNA or RNA but not both
lack independent metabolic system
require host of cell for replication
consist of intracellular reproductive cycle and extracellular transmissive cycle
Unicellular
protozoa, fungi, bacteria, riskettsiae, mycoplasmas, chlamydia
unicellular
both DNA and RNA
binary fission
Viruses
obligate intraceullar
either DNA or RNA
two life cycles
extracellular (transmissive, inert)
intracellular (reproductive)
viroids
replicating in nucleus
virusoids
replicating in cytoplasm
prions
protein only (no nucleic acid genome)
high resistance to heat, UV irradiation, chemical
prion protein
PrPc
PrPsc
PrPc
present in normal cells
PrPsc
abnormal conformational aberration: amyloid formation
Building blocks for non-enveloped viruses
protein subunit
structure unit
capsomer
capsid (coat or shell)
nucleocapsid
building blocks for enveloped viruses
building blocks of non-enveloped viruses
peplomer/spike
matrix protein
lipids
spike or peplomer
carbohydrate side chain
Enveloped viruses
epidemiology: short survival in environment, labile, easier to inactivate, often associated with seasonal disease
pathogenesis: budding through infected cells, chronic/persistent infection
immunology: glycoprotein antigens: VN, CMI, vaccine immunity
Non-envelope viruses
only nucleocapsid protein
more resistant: longer survival in environment, not seasonal disease, difficult to inactivate
pathogenesis: lytic cell infection: often associated with acute disease, less chronic
Icosahedra (cubical):
efficient package
