Viral Pathogenicity

Question 1

What are the five questions on pathogenesis?

Answer 1

How does virus enter host?

What cell does it target?

What is normal function of this cell?

How does virus alter/interfere with cell function?

What effect will this have on host?

Question 2

What are the routes of viral entry?

Answer 2

Respiratory
Oral
Cutaneous localised
Percutaneous
Sexually transmitted

Question 3

What is the difference between specific and non-specific ligand binding of viruses?

Answer 3

Specific = can define host species and cell type a virus may infect, e.g. HIV and FIV affect CD4+ T lymphocytes.

Non-specific = wide host range potential

Question 4

In what four ways can a virus alter function of a cell?

Answer 4

Lytic infection - cell death, causing complete loss of function

Latent infection - persist within cell, can alter rate of cell division and growth

Persistent infection - failure of immune system to clear infection

Enhanced cell growth - increased cell division, leading to cell growth and tumour formation

Question 5

In what ways might a host respond to a viral infection?

Answer 5

Epithelium - interferon/pro-inflammatory cytokines/chemokines

Fever

Sickness behaviour

Defence mechanisms - Interferon-alpha