Antivirals

Question 1

Name features of Influenza A?

Answer 1

Main seasonal outbreak
Multiple host species
Antigenic drift and shift

Question 2

what are common complications of Influenza ?

Answer 2

Bronchitis, pneumonia
– Sinusitis
– Exacerbation of underlying disease

Question 3

what are features of Influenza B?

Answer 3

Only in humans

Question 4

what are the structures of Influenza A ?

Answer 4

RNA 
Protein envelope 
Lipid envelope 
M2 and M1 
Proteins on outside :
Neuraminidase and Hemaggltuinin

Question 5

what can Hemagglutinin do?

Answer 5

recognise human respiratory cells to stick to surface - salic acid , URT

Question 6

what does the M2 ion channel do ?

Answer 6

once the virus enters the host cell this cannel allows H+ ion to enter to break uo the virus particle to replicate it self

Question 7

how do Amantadine and Rimantadine work ? what do they work on ?
what else do they work on ?

Answer 7

Antivirals that work in Influnza A
Block M2 ion channels = inhibit viral uncoating
Parkinson’s

Question 8

what are side effects of amantidine ?

Answer 8

CNS and renal

Question 9

how was resistance developed for Amantadine ?

Answer 9

single point mutation in M2 gene which is transmissible

the shape of channel changes so drug does not bind into the channel

Question 10

what does Neuraminidase do ?

Answer 10

Breaks the Sialic acid and Heamagglutinin bond and allows a budding virus particle to break off

Question 11

what is the pharmokinetics of Zanamavir ?

Answer 11

Low bioavail - dry aersol needed
Acid degrades it
long half life
renally excreted

Question 12

what is an advantage of Oesltamivir ?

Answer 12

Pro-drug with high bio avail so in tablet form

Question 13

how does Oesltamivir and Zanamavir work?

Answer 13

competitively inhibits the NA enzymes so virus aggregation occurs and stays in the cell

Question 14

what is a goal when starting Zanamavir and oesltamivir ? what can it lead to ?

Answer 14

start treatment early when symptoms start

severity and duration decreases , reduction in mortality

Question 15

what is a major use of Osetltamvir ?

Answer 15

seasonal prophylaxis

Question 16

what side effects of Zanamavir ?

Answer 16

vomiting
abdo pain
epistaxis
low side effect profile

Question 17

what is the proper name for Bird flu ?

Answer 17

H5N1 infection

Question 18

how do we reduce resistance globally ?

Answer 18

survelliance -
WHO system
NA inhibitor Susceptibility network

Question 19

how do virus’ develop resistance to NA inhibitors ?

Answer 19

Change in shape of enzyme

Question 20

what strain develop resistance in Oseltamivir ?

Answer 20

H1N1 (human strain) - not triggered by over use of antivirals

Question 21

why is Oseltamivir now still in use ?

Answer 21

circulating H1N1 human is replaced by swine H1N1 which is susceptible to it

Question 22

what are primary care guidlines in flu outbreaks?

Answer 22

Healthy people: no Rx unless pt felt to be at risk
– At risk (inc preg): oseltamivir asap (no need for confirmation)
– Severely immunosuppressed: oseltamivir or inhaled zanamivir
(esp if H1N1)

Question 23

what are secondary care guildlines in flu ?

Answer 23

if suspected give Oseltamivir asap

if H1N1 is high try Zanamivir

Question 24

what is EBV associated with?

Answer 24

non-malignant and malignant

lymphomas

Question 25

what is general structure of HSV and VZV ?

Answer 25

large double-stranded DNA genome | covered by a capsid and lipid bilayer envelope.

Question 26

how do HSV enter cells ?

Answer 26

via MHC class molecules

Question 27

how does shingles present ? | what kind of patients will you see it in ?

Answer 27

reactivation of the virus (Herpes zoster) which lies dormant in a dorsal root ganglion after primary chickenpox infection. elderly and immunocompromised

Question 28

What is the main treatment principle of Shingles?

Answer 28

start antivirals within 72 hours

Question 29

what is the main clincinal differences of HSV 1 and 2 ?

Answer 29

``` 1= genital or oral ulceration 2 = Just genital ```

Question 30

what is treatment of HSV?

Answer 30

Oral aciclovir or valaciclovir are administered for 7-10 days to treat the multiple painful genital herpes lesions

Question 31

What is common complication of HSV?

Answer 31

recurrent lesions to occur from reactivation of latent | virus in the dorsal root ganglia. Symptoms are usually less severe than the primary episode.

Question 32

How does Acyclovir and Valaciclovir work ?

Answer 32

nucleoside inhibitors of viral DNA replication

Question 33

how does Aciclovir work ? why is it good for humans

Answer 33

guanosine analogue active against many DNA viruses by inhibiting synthesis of viral DNA. Initial activity relies on phosphorylation by a viral protein (thymidine kinase) limiting their initial human cell toxicity

Question 34

how does resistance to Aciclovir develop?

Answer 34

change in thymidine kinase- prevalent in immunocompromised

Question 35

what are side effects of Aciclovir ? | what D-D interaction ocurs?

Answer 35

N+V Photo sensitivity antibiotics could = Nephrotoxicity

Question 36

what is PK of aciclovir ?

Answer 36

It is well distributed and most is eliminated by the kidneys with a half-life of around 3 hours