Pathogenesis of viral infections

Question 1

What are 4 major consequences of infection?

Answer 1

1. Abortive
2. Productive
3. Latent
4. Transformation

Question 2

What are some productive consequences of infection?

Answer 2

Death: Necrosis, apoptosis

Persistence

Question 3

What are some routes for infection?

Answer 3

Skin
Respiratory tract
Oropharynx
GI tract
Urogenital tract
Conjunctiva
Direct introduction (insect)

Question 4

What happens if a virus invades a mucosal surface (localized infection)?

Answer 4

invades cells – replicates
release + disruption of basement membrane
M cells pick it up
infected M cell spreads the virus –> lymph nodes –> viremia –> salivary gland, epithelial surfaces, brain, other

Question 5

What are some local effects of virus infection?

Answer 5

1. Cell destruction
2. Loss of function
3. Growth
4. Cell transformation

Question 6

What are 3 ways cell destruction can occur with viral infection

Answer 6

1. virus induced
2. immune mediated
3. apoptosis

Question 7

What are some viral effects on the animal?

Answer 7

None
inflammation
fever, malaise, anorexia
mucus
diarrhea
loss of function
abnormal development 
abortion
secondary infection

Question 8

What are 3 ways virus disseminates

Answer 8

1. Localized versus systemic infection
2. Hematogenous spread
3. Neural spread

Question 9

How is a virus determined localized vs.systemic based on dissemination?

Answer 9

budding at luminal surface - localized

released at basal surface - systemic infection

Question 10

What are 3 molecular determinants of viral virulence?

Answer 10

Envelope glycoproteins and capsid proteins
Viral polymerase and other proteins
Noncoding regions of viral genome

Question 11

What are 6 mechanisms of viral virulence

Answer 11

1. Modulation of host immune response
2. Modulation of growth factors and cytokines
3. Modulation of apoptosis
4. Disruption of intracellular calcium homeostasis
5. Production of reactive oxygen and nitrogen intermediates
6. Modulation of intracellular deoxynucleoside triphosphate pool

Question 12

What are different routes of viral transmission?

Answer 12

Saliva
Aerosol
Feces
skin scabs
urine
blood
genital secretions
milk/colostrum

Question 13

What are some host factors that determine the outcome of a viral infection?

Answer 13

Immune status
Genetic background
Age 
Nutrition
Presence or absence of certain hormones