Virus Pathogenesis

Question 1

What are 3 virus pathogenic mechanisms?

Answer 1

• cell destruction following virus infection
• virus induced changes to cellular gene expression (cellular transformation by tumour viruses)
• immunopathogenic disease

Question 2

What is an example of cell destruction following viral infection?

Answer 2

Death of T4+ cells by HIV

Question 3

What are 2 examples of immunopathogenic disease?

Answer 3

-influenza A virus

Coxsackievirus- induced myocarditis

Question 4

What are the site of viral entry? (7)

Answer 4

• conjunctiva
• arthropod
• capillary
• skin
• respiratory tract
• alimentary tract
• urogenital tract

Question 5

What kind of virus does the influenza A virus cause?

Answer 5

respiratory infection

Question 6

What kind of infections does enterovirus cause?

Answer 6

• enteric

- neurological

Question 7

Describe the process of infection by the influenza A virus.

Answer 7

• virus infects cells of the respiratory tract
• destruction of respiratory epithelium
• altered cytokine expression leading to fever

Question 8

Name 2 examples of cytokines that when expression is altered can lead to fever.

Answer 8

• interleukin-1

- interferon

Question 9

What can cause a cytokine storm?

Answer 9

Avian influenza virus (H5N1)

Question 10

What is antigenic drift?

Answer 10

gradual evolution of viruses to generate antigenic variants

Question 11

What is antigenic shift??

Answer 11

significant changes in virus antigenic structure

Question 12

What plays a key role in generating new virus types through antigenic shift?

Answer 12

non-human hosts

Question 13

Name 5 examples of conditions and the enterovirus they are caused by.

Answer 13

• poliomyelitis (poliovirus)
• aseptic meningitis (many enteroviruses)
• myocarditis (coxsackie B viruses)
• pancreatitis (coxsackie B viurses)
• respiratory infection (many enteroviruses)

Question 14

Give an example of a latent virus which has 2 types.

Answer 14

• Herpes simplex virus
• Type 1 =cold sores
• Type 2= genital lesions

Question 15

Describe the process of infection by the latent herpes virus.

Answer 15

• primary infection of epithelial cells
• virus migrates to ganglia
• virus remains latent in nucleus= no virus replication
• stimuli such as sunlight reactivates virus
• virus migration to epithelial cells leading to virus replication

Question 16

Give 2 examples of viruses which can induce tumours and what they can cause.

Answer 16

• Papillomaviruses- cervical carcinoma

- Retroviruses- lymphomas and leukaemias

Question 17

What does HTLV-1 cause and how is it transmitted?

Answer 17

• variety of diseases including leukaemia (adult T cell lymphoma-leukaemia)
• transmission by blood and mother to child

Question 18

What does HTLV-1 do?

Answer 18

modifies host cell gene expression using a transactivating protein (tax)

Question 19

Describe the process in which retrovirus can induce tumours.

Answer 19

• virus infects cell
• virus nucleic acid, as DNA , integrates into cellular genome
• virus causes changes in cellular gene expression
• uncontrolled cell multiplication and tumour formation