Structural basis of disease - viruses

Question 1

what happens when the herpes genetic material enters the nucleus and why

Answer 1

circulisation of the linear DNA occurs
it enters a dormant state when circular and then reactivated under stress

Question 2

what is the function of tegument proteins

Answer 2

regulate production of mRNAs and proteins IE immediate early genes

Question 3

what is the purpose of tegument proteins for viruses

Answer 3

viruses release tegument proteins to dampen the innate immune response
promotes production of early (E) proteins - replication and late (L) proteins for viral assembly

Question 4

what are the genomic features of the herpes virus

Answer 4

dsDNA - 120-240kb
linear in acute phase
circular in dormant phase

Question 5

how does herpes regulate the host immune response

Answer 5

down-regulation of pro-inflammatories
down-regulate MHC-II in infected cells
can infect B-cells and T-cells

Question 6

what does IFNy response produce

Answer 6

autocrine - inhibition of viral replication/apoptosis
paracrine - up-regulation of MHC-I/NK cell activation

Question 7

what is dexamethasome

Answer 7

a corticosteroid used in a wide range of conditions (anti-inflammatory/immunosuppressant)

Question 8

so why does dexamethasome work

Answer 8

because in alot of cases its not the virus itself that kills, its the immune response - such as in herpes

Question 9

what is the function of protease inhibitors

Answer 9

stops polyprotein chains from forming into a mature viral protein by inhibiting protease

Question 10

where does protease inhibitors act in covid

Answer 10

at the polyprotein processing stage
basically viruses bring their own proteases with them so they can cleave and modify their polyprotein chains into a mature viral protein
protease inhibitors prevent this

Question 11

how are monoclonal antibodies such as Sotrovimab used for viruses

Answer 11

recognises and binds to the spike protein that viruses use to attach to cells
prevents viruses from entering the cells

Question 12

what are examples of cytoplasmic viral structures

Answer 12

coronaviridae - double membrane vesicle where the dsRNA is produced
poxvididae - forms a viruplasm for viral replication and assembly

Question 13

what is an example of a nuclear viral structure

Answer 13

herpes - form nuclear replication compartments for viral replication and late gene transcription

Question 14

what are some examples of RNA viruses

Answer 14

measles
mumps
paramyxovirus

Question 15

features of mumps

Answer 15

infection of the ductal epithelium
leads to parotitis
mumps virus can cross BBB
able to infect ependymal cells

Question 16

features of paramyxovirus

Answer 16

downregulates the innate immune response by interfering with interferon responses

Question 17

in a viral genome what is the difference between a positive/negative ssRNA

Answer 17

positive - needs to synthesise its complementary strand for transcription of mRNA
negative - is already complementary to mRNA so can begin transcription without a complementary positive strand

Question 18

how does influenza enter the cell

Answer 18

1 - attachment
2 - endocytosis
3 - acidification of the endosome
4 - change in pH causes conformational change of haemagluttinin
5 - causes the release of the virus from the endosome via the loss of the envelope

Question 19

what are the features of haemagluttinin

Answer 19

trimeric membrane protein
binds glycosylated proteins on the surface membranes of the cell

Question 20

how does the structure of haemagluttinin alter due to a change in pH

Answer 20

after binding of the glycosylated protein
causes a reorientation and exposure of the fusion peptide
this exposure leads to the fusion of the viral membrane and the cell membrane

Question 21

function of neuraminidase

Answer 21

cell surface membrane on viruse
hydrolyses sialic acid glycosylation
needed to release the virus - otherwise it would just be fused and stuck to the cell membrane

Question 22

what does haemagluttinin specifically bind to

Answer 22

sialic-acid

Question 23

which viruses have positive/negative RNA strands

Answer 23

negative - paramyxovirus/orthomyxovirus
positive - coronavirus/HIV

Question 24

what is unique about the HIV virus

Answer 24

possesses reverse transcriptase
RNA to DNA

Question 25

which viral genomes affect bacteria/plants/animals

Answer 25

bacteria - ssDNA and dsDNA
plants - ssRNA and dsRNA
animals - dsDNA, dsRNA and ssRNA

Question 26

what viral structure is specific for the infection of bacteria

Answer 26

head and tail structure
enveloped structure

Question 27

what viral structure is specific for the infection of plants

Answer 27

helical structure
icosahedral structure
envelope structure

Question 28

what viral structure is specific for the infection of animals

Answer 28

icosahedral structure
envelope structure