Viral Pathogens: Classification, Biology, Disease 2

Question 1

What is the typical course of HIV-1 infection?

Answer 1

HIV infects T cells due to CD4

AIDS is attained when there is immunodeficiency

Question 2

Why is immunodeficiency advantageous to HIV?

Answer 2

Viruses evade immune responses by replicating in the immune cells

By doing so the immune cells hide the virus from other immune cells

Inhibiting immune cell function allows other pathogens to replicate in virus infected hosts and thus disease occurs

Question 3

How can HIV directly promote T cell killing?

Answer 3

By infection of T cells and viral replication in permissive T cells

Stimulates apoptosis

Only 5% of cells are T cells

Question 4

How can HIV indirectly promote T cell killing?

Answer 4

In non permissive T cells

Virus is recognised by the innate immune system in the cell

Activates pyroptosis - causes inflammation therefore more T cells are recruited to the site of infection

95% of cells are non-permissive

Question 5

Give examples of HIV associated pathogens

Answer 5

Virus - herpes simplex virus

Bacteria - salmonella

Fungus - Candida

Parasite - cryptosporidium

Question 6

What are the two possible routes of infection in HIV affected induviduals?

Answer 6

Primary infection - can be resolved by immunosuppression

Reactivation from latency - virus resides without replicating

Question 7

What is AIDS?

Answer 7

Cancers and opportunistic infections

Question 8

Describe how latency can occur

Answer 8

When epithelial cells are infected it’s possible for viruses to enter the dendritic nervous cell

The virus can then go undetected and stay in the cell body of the neuron without replicating

The immune cells cannot cross the blood brain barrier easily so the virus can go undetected

Question 9

Give examples of viruses that cause cancer

Answer 9

Hepatitis B

Hepatitis C

Human herpes virus 8