Virology week 1

Question 1

t/f epizootic diseases exceed the panzootic baseline?

Answer 1

F they exceed the enzootic (endemic) baseline

Question 2

what are the three parameters of defining incidence in acute diseases?

Answer 2

S/P I/P C/I
S=susceptible population
I=those infected
C=those cases/diseased

Question 3

What is the difference between prospective studies and retrospective studies? two main differences

Answer 3

Prospective- very expensive, can require a lot of subjects
retrospective- cost-effective, limited subjects needed

Question 4

Direct contact is mostly associated with which type of virus? (enveloped or nonenveloped)

Answer 4

enveloped. this is because they have a hard time surviving in the environment

Question 5

What is the main difference between arbo- biological vectors and mechanical vectors?

Answer 5

viruses replicate in the biological vectors and are more efficient compared to mechanical (no replication in these vectors)

Question 6

What is a classical zoonotic viral disease? why?

Answer 6

rabies. transmissible from animals to humans

Question 7

which modes of transmission are preventable and caused by veterinarians?

Answer 7

latrogenic and nosocomial with nosocomial being directly from the hosptial

Question 8

what is a latent virus and what does it mean if recrudescence occurs?

Answer 8

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

Question 9

2 important routes of virus shedding?

Answer 9

respiratory secretions and feces

Question 10

t/f all viruses shed?

Answer 10

f CNS and retroviruses do not shed

Question 11

What are the 7 stages of the virus replication cycle?

Answer 11

attachment - penetration - uncoating - macromolecular synthesis - replication - assembly of virions - release

Question 12

How do VAPs (viral attachment proteins) vary on enveloped and nonenveloped viruses?

Answer 12

nonenveloped have VAPs that are a part of the capsid.
enveloped viruses VAPs are glycoproteins on the envelope

Question 13

t/f if the host does not have a receptor for that virus then it will not get infected

Answer 13

t specific receptors for those viruses must be present for recognition/infection

Question 14

3 ways viruses penetrate the cell

Answer 14

translocation- nonenveloped
endocytosis- enveloped. taken into a vesicle
fusion- enveloped. lipid bilayers fuse.

Question 15

why does uncoating have to occur?

Answer 15

releases nucleic acid genome into cell. it can now use cellular metabolism to synthesize viral proteins

Question 16

Where do all DNA viruses replicate? what is the exception?

Answer 16

Nucleus. exception is poxvirus

Question 17

all RNA viruses replicate in the cytoplasm except for?

Answer 17

coronaviruses, retroviruses, and orthomyxoviruses

Question 18

What is Cytopathic effect? example?

Answer 18

morphological changes that a cell goes through after interacting with a virus. rounding, lysis, syncytia.

Question 19

what general type of viruses can survive in the GI tract and infect there?

Answer 19

nonenveloped viruses because they can survive harsh environments.

Question 20

viremia?

Answer 20

virus travels through blood. most efficient systematic spread

Question 21

What routes of viral spread are inefficient?

Answer 21

neural- too slow
lymphatic- inefficient
local- few cells effected

Question 22

What two things cause CPE (cytopathic effect) of cells?

Answer 22

direct pathological injury
side effect from the cells altered metabolism after their machinery was hijacked to make viruses

Question 23

what is the infectious agent in most viruses?

Answer 23

nucleic acids

Question 24

T/F bacteria and viruses are sensitive to antibiotics

Answer 24

just bacteria not viruses

Question 25

What is the difference between prions and viroids/virusoids?

Answer 25

prions are proteins only, they cant be nucleic acids like the others can. they are also always present in PrPc form

Question 26

Nucleocapsid?

Answer 26

mature infectious virus.
the only structure of a nonenveloped virus

Question 27

where did the enveloped protein get its lipid bilayer?

Answer 27

from the cell that it came out of through budding

Question 28

Enveloped or Nonenveloped virus: which is easier to inactivate?

Answer 28

enveloped. this is due to the lipid bilayer. this also makes it heat sensitive.

Question 29

Why is the enveloped virus noninfectious if it loses its envelope?

Answer 29

the enveloope has spike or peplomer glycoproteins embedded. these are what the host recognizes. without these, it cant bind

Question 30

What is the only single stranded DNA virus?

Answer 30

parvoviridae

Question 31

What is the only complex nucleocapsid in DNA viruses?

Answer 31

Poxviridae

Question 32

What are the only two double stranded RNA viruses

Answer 32

Birnaviridae and Reoviridae

Question 33

which are generally larger viruses, DNA or RNA?

Answer 33

DNA

Question 34

example of virus that enter through skin?

Answer 34

herpesvirus
poxvirus

Question 35

Viruses that enter through the respiratory tract?

Answer 35

herpesvirus
paramyxoviruses

Question 36

enveloped viruses are generally (seasonal or year round) and can be associated with (chronic or acute) infections

Answer 36

seasonal, chronic

Question 37

Pathogenesis of a nonenveloped protein?

Answer 37

lysis. Associated with a less chronic infection due to Killing the cells

Question 38

All enveloped viruses have a ______ symmetry

Answer 38

helical

Question 39

What is the most efficient symmetry for a virus?

Answer 39

Icosahedral. Triangles and cubical