viral properties and disease

Question 1

5 outcomes of viral infection

Answer 1

acute infection (followed by viral clearance; can cause “accidental” tissue infection with permanent damage), persistent infection (latent, slow, transforming), long incubations, oncogenesis

Question 2

examples of viruses causing acute infection and clearance

Answer 2

colds, influenza, rhinovirus, rotavirus

Question 3

examples of viruses causing acute infection and death

Answer 3

smallpox, dengue

Question 4

examples of viruses causing acute infection and accidental pathogenesis

Answer 4

polio (paralysis), rubella (deafness, cataracts, congenital heart disease)

Question 5

feature of chronic persistent viral infection

Answer 5

low level replication in regenrative tissue

Question 6

example of chronic persistent viral infection

Answer 6

warts

Question 7

feature of latent persistent viral infection

Answer 7

viral genomes maintained (e.g. neurones don’t divide so when nerve infected won’t be recognised by immune system) but no virus seen until immunocompromised

Question 8

example of latent persistent viral infection

Answer 8

Herpes

Question 9

what is the strategy of viral persistence

Answer 9

viruses contain many accessory genes allowing it to evade immune system, especially in skin and nervous system where immune activity is low

Question 10

what is oncogenesis

Answer 10

viruses that cause cancer by encoding oncogenes

Question 11

how does oncogenesis interfere with cell cycle

Answer 11

promote synthesis of virus and inhibit tumour suppressor genes

Question 12

examples of oncogenesis viral infection

Answer 12

hep B and C, Epstein-Barr, HTLV-1 which causes leukaemia

Question 13

define retrograde transport

Answer 13

virus transported from primary site of infection away from skin to CNS

Question 14

define anterograde transport

Answer 14

virus transported to skin from neurones

Question 15

outcomes of virus infection

Answer 15

balance of host response and viral virulence: sequence, load, co-morbidities, co-infections, other medications, host genetics, host age, host gender

Question 16

viral sequence as outcome of infection

Answer 16

vary in virulence due to mutation

Question 17

virus load as outcome of infection

Answer 17

dose of virus received

Question 18

host immune response as outcome of infection

Answer 18

resistance

Question 19

host co-morbidity as outcome of infection

Answer 19

other diseases present, pregnant, age, obesity

Question 20

co-infections as outcome of infection

Answer 20

susceptible to other infections

Question 21

other medications as outcome of infection

Answer 21

may affect immunity and susceptibility

Question 22

host genetics, age and gender as outcome of infection

Answer 22

presence of particular mutated genes or different alleles may provide protection or increase susceptibility