Virology week 1 Flashcards
t/f epizootic diseases exceed the panzootic baseline?
F they exceed the enzootic (endemic) baseline
what are the three parameters of defining incidence in acute diseases?
S/P I/P C/I
S=susceptible population
I=those infected
C=those cases/diseased
What is the difference between prospective studies and retrospective studies? two main differences
Prospective- very expensive, can require a lot of subjects
retrospective- cost-effective, limited subjects needed
Direct contact is mostly associated with which type of virus? (enveloped or nonenveloped)
enveloped. this is because they have a hard time surviving in the environment
What is the main difference between arbo- biological vectors and mechanical vectors?
viruses replicate in the biological vectors and are more efficient compared to mechanical (no replication in these vectors)
What is a classical zoonotic viral disease? why?
rabies. transmissible from animals to humans
which modes of transmission are preventable and caused by veterinarians?
latrogenic and nosocomial with nosocomial being directly from the hosptial
what is a latent virus and what does it mean if recrudescence occurs?
latent viruses incorporate into the genome. think herpes alpha in the ganglia. and, during recrudescence, stress causes the disease to flair up a new immune response will occur
2 important routes of virus shedding?
respiratory secretions and feces
t/f all viruses shed?
f CNS and retroviruses do not shed
What are the 7 stages of the virus replication cycle?
attachment - penetration - uncoating - macromolecular synthesis - replication - assembly of virions - release
How do VAPs (viral attachment proteins) vary on enveloped and nonenveloped viruses?
nonenveloped have VAPs that are a part of the capsid.
enveloped viruses VAPs are glycoproteins on the envelope
t/f if the host does not have a receptor for that virus then it will not get infected
t specific receptors for those viruses must be present for recognition/infection
3 ways viruses penetrate the cell
translocation- nonenveloped
endocytosis- enveloped. taken into a vesicle
fusion- enveloped. lipid bilayers fuse.
why does uncoating have to occur?
releases nucleic acid genome into cell. it can now use cellular metabolism to synthesize viral proteins
Where do all DNA viruses replicate? what is the exception?
Nucleus. exception is poxvirus
all RNA viruses replicate in the cytoplasm except for?
coronaviruses, retroviruses, and orthomyxoviruses
What is Cytopathic effect? example?
morphological changes that a cell goes through after interacting with a virus. rounding, lysis, syncytia.
what general type of viruses can survive in the GI tract and infect there?
nonenveloped viruses because they can survive harsh environments.
viremia?
virus travels through blood. most efficient systematic spread
What routes of viral spread are inefficient?
neural- too slow
lymphatic- inefficient
local- few cells effected
What two things cause CPE (cytopathic effect) of cells?
direct pathological injury
side effect from the cells altered metabolism after their machinery was hijacked to make viruses
what is the infectious agent in most viruses?
nucleic acids
T/F bacteria and viruses are sensitive to antibiotics
just bacteria not viruses
What is the difference between prions and viroids/virusoids?
prions are proteins only, they cant be nucleic acids like the others can. they are also always present in PrPc form
Nucleocapsid?
mature infectious virus.
the only structure of a nonenveloped virus
where did the enveloped protein get its lipid bilayer?
from the cell that it came out of through budding
Enveloped or Nonenveloped virus: which is easier to inactivate?
enveloped. this is due to the lipid bilayer. this also makes it heat sensitive.
Why is the enveloped virus noninfectious if it loses its envelope?
the enveloope has spike or peplomer glycoproteins embedded. these are what the host recognizes. without these, it cant bind
What is the only single stranded DNA virus?
parvoviridae
What is the only complex nucleocapsid in DNA viruses?
Poxviridae
What are the only two double stranded RNA viruses
Birnaviridae and Reoviridae
which are generally larger viruses, DNA or RNA?
DNA
example of virus that enter through skin?
herpesvirus
poxvirus
Viruses that enter through the respiratory tract?
herpesvirus
paramyxoviruses
enveloped viruses are generally (seasonal or year round) and can be associated with (chronic or acute) infections
seasonal, chronic
Pathogenesis of a nonenveloped protein?
lysis. Associated with a less chronic infection due to Killing the cells
All enveloped viruses have a ______ symmetry
helical
What is the most efficient symmetry for a virus?
Icosahedral. Triangles and cubical
