Virology

Question 1

are viruses alive

Answer 1

no, but they are obligate intracellular parasites

Question 2

how do membrane-bound viruses get into cells

Answer 2

attachment to the membrane
fusion of the membrane
endocytosis into endosomes then released into

Question 3

how do non-membrane bound viruses get into cells

Answer 3

attachment to the membrane
direct penetration of the membrane

Question 4

virus life cycle

Answer 4

recognition
attachment
fusion or penetration
uncoating
transcription
protein synthesis
replication
envelopment or assembly
budding or lysis
release

Question 5

what are the properties of a viral genome

Answer 5

type of nucleic acid
strandedness
linear or circular
sense
number of segments
nucleotide sequence

Question 6

why is the genome of a negative sense RNA virus non-infectious

Answer 6

it is not in the same sense (direction) as mRNA and cannot be transcribed
brings transcriptase to make a positive strand

Question 7

types of virus DNA molecules

Answer 7

linear single-stranded
circular single-stranded
linear duplex
duplex with closed ends
closed circular duplexes

Question 8

why do the ends of linear single-stranded DNA molecules fold up

Answer 8

to prevent exposed ends from being detected as damaged DNA by the host cell and destroyed

Question 9

why do infections of herpes simplex keep coming back

Answer 9

primary infection travels up the peripheral nerve to sensory neuron in the spinal cord
immune system will not attach spinal cord

Question 10

what is the difference between chicken pox and shingles

Answer 10

chicken pox is first infection and is in the nerves
shingles is the secondary eruption of chicken pox at the ganglia

Question 11

explain how smallpox was eradicated

Answer 11

vaccination

Question 12

big successes of anti-viral therapy

Answer 12

HIV
Hep A and B
Herpes
Influenza
RSV

Question 13

how is the influenza virion constructed and what does it look like

Answer 13

enveloped in a membrane derived from the host cell
studded with HA and NA

Question 14

which viral proteins are the targets for the host immune response to influenza infection

Answer 14

neuraminidase and hemagglutinin

Question 15

what are the genetic changes in the influenza genome that contribute to “drift” and “shift”

Answer 15

drift - subtle changes to existing antigens by random mutation
shift - two or more chains combine

Question 16

what does hemagglutinin bind on the host cell

Answer 16

sialic acid (a cell surface carbohydrate)

Question 17

why does genetic variation over time make it difficult to generate long-term vaccines for influenza

Answer 17

antigenic drift causes slight flu mutations from which humans have partial or no immunity

Question 18

difference between the R number and growth rate (coronavirus)

Answer 18

R number is the average number of secondary infections produced by a single infected individual
growth rate is how quickly the number of infections change

Question 19

growth rate (coronavirus)

Answer 19

the growth rate is how quickly the number of infections changes

Question 20

R number (coronavirus)

Answer 20

R number is the average number of secondary infections produced by a single infected individual

Question 21

difference between the r number and growth rate

Answer 21

R alone does not tell us how quickly an epidemic is changing

Question 22

nature of a coronavirus particle and its genomic nucleic acid

Answer 22

enveloped and spherical particles of 100-160nm in diameter
positive sense single-strand RNA genome

Question 23

how does coronavirus attach to host cells

Answer 23

spike protein binds to receptor on cell surface

Question 24

3 types of coronavirus tests
advantages and disadvantages

Answer 24

PCR test
“Lateral flow” tests
Reverse transcription loop-mediated