Viral Pathogenicity

Question 1

Outcomes of virus infection of a cell

Answer 1

1. Cell death
2. Chronic infection
3. Latency
4. Transformation

Question 2

Outcome of viral infection: cell death

Answer 2

Cytolytic/ cytocidal infection;
Many underlying reasons;
In vitro - production of cytopathic effect;
In Vivo - …

Question 3

Outcome of viral infection: chronic infection

Answer 3

Continuous viral replication but cell survives;
Hepatitis B viral infection;
Housekeeping and luxury functions of cell;

Question 4

Outcome of viral infection: latency

Answer 4

No viral replication, no production of viral proteins;
Once infected, always infected;
Virus replication can be reactivated;
Primary and secondary infections;
All herpes viruses

Question 5

Outcome of viral infection: Transformation

Answer 5

Immortalisation of cell;

Do viruses cause cancer - yes

Question 6

Entry into new host

Answer 6

Placenta;
Skin - resistant if intact;
Gastrointestinal tract;
Mucosal surfaces - oral, genital tract, naso-pharynx;
Respiratory tract;

Question 7

Spread within host

Answer 7

Local (cell to cell);
Lymphatics;
Bloodstream (viraemia - access to placenta);
Axonal pathways (rabies);

Question 8

Interaction with target cells determined by?

Answer 8

Tropism of virus

Question 9

Viral shedding

Answer 9

Skin - vesicles;
Gastrointestinal tract - saliva, faeces;
Respiratory tract - droplets;
Urogenital tract - urine, semen, female genital tract secretions;
Breast milk;
Blood - HIV

Question 10

Viruses and cancer

Answer 10

EBV - lymphomas, nasopharyngeal carcinoma;
Hepatitis B and C viruses - hepatocellular carcinoma;
Human papilloma viruses - cancer of uterine cervix;