Prevention and Treatment of Viral Disease

Question 1

define prophylaxis

Answer 1

preventing disease before the aetiologic agent is acquired i.e. vaccination,

Question 2

define therapy

Answer 2

treating the disease after host infection

Question 3

list and explain the different types of viral vaccine

Answer 3

attenuation - live natural virus vaccine, reduced virulence, mild infection
inactivation - inactivated virus vaccine, genome destroyed, not infectious, may add adjuvants to aid response
fractionation - non recombinant purified subunit vaccine, genome treated with proteases
cloning - live virus vector/DNA/virus-like particle vaccine

Question 4

compare pros/cons of live and inactivated virus

Answer 4

Live
\+rapid, broad, long lived immunity, dose sparing, cellular immunity
-requires attenuation, may revert
Inactive
\+safe, made from wild type virus
-frequent boosting requires, high dose

Question 5

give examples of successful vaccines

Answer 5

polio, smallpox

Question 6

describe the 2 types of poliovirus vaccine

Answer 6

SALK = inactivated, can't replicate, large dose
SABINE = live attenuated, can't be given to immunosuppressed, aims to stop using

Question 7

describe 2 types of flu vaccine

Answer 7

Inactivated - consists of spike proteins, given to people at risk
live attenuated - nasal spray, cold adapted, regularly updated due to fast evolution

Question 8

name the 2 types of passive immunisation for the ebola virus

Answer 8

zmapp - antibodies raised against ebola G protein

serum therapy - blood of survivors

Question 9

what is used in antiviral treatment? why? negatives?

Answer 9

interferons which induce an antiviral response, as well as inflammation and fever

Question 10

what do antiviral drugs tend to target?

Answer 10

viral enzymes acting as substrate analogues

Question 11

what are nucleoside analogues? what do they target?

Answer 11

look like a base but lack 3’ OH so terminates the chain of DNA/RNA

Question 12

how is acyclovir specific?

Answer 12

only activated inside virus infected cells, higher affinity for viral DNA polymerase than host cell polymerase, resistance is rare, phosphorylated by viral thymidine kinase

Question 13

summarise how the influenza infects a cells

Answer 13

low endosome pH activates m2 channel on capsid allowing protons influx into virus, bonds holding capsid together undone and viral components released

Question 14

how do adamantanes inhibit flu?

Answer 14

fits into M2 channel so stops protons from flowing through M2 channel so virus locked in

Question 15

how do neuraminidase inhibitors inhibit the flu?

Answer 15

virus enters cell by binding to sialic acid, host cell dies in infection, virus leaves cell by producing neuraminidase which destroys sialic acid on cell surface so daughter virus doesn’t infect original cell
inhibiting this means enzymes will latch back down on old cell and not spread