L14- Patterns of viral disease

Question 1

What are the sites of entry and routes of infection?

Answer 1

• Skin e.g HSV
• Direct contact e.g Herpes
• Respiratory tract e.g influenza
• Aerosols

Question 2

What are the sexually transmitted infections?

Answer 2

• Genital herpes
• Genital warts
• Cervical cancer
• HIV/AIDs

Question 3

How does the innate immune system respond to pathogens?

Answer 3

• Protection against infection: IFN’s binding to cell surfaces to prevent viruses entering (antiviral)
• Eradication of established infection: NK cells carrying out lysis and killing of infected cells

Question 4

How does the adaptive immune system respond to pathogens?

Answer 4

• Protection against infection: B cells release antibodies to neutralise toxins
• Eradication of established infection: CD8+ T cells carry out lysis and killing of infected cells

Question 5

What do Type 1 interferons do?

Answer 5

1. Induce cellular resistance where viral spread is limited by activating endogenous protein kinases that stop viral nucleic acid synthesis
2. Induce MHC class I molecules which promotes viral recognition and
3. Killing by cytotoxic T cells

Question 6

What does a neutralising antibody do?

Answer 6

• Can block virus infection by binding to the receptor on host cells and blocking viral attachment
• Prevents viral entry
• Blocking uncoating and fusion if enters cell

Question 7

What is the antigenic diversity of polioviruses?

Answer 7

• 3 serotypes and each virus is neutralised only by its own specific antibody

Question 8

What is the Salk vaccine?

Answer 8

• Licensed 1955
• Contains dead and inactivated strains of poliovirus type 1,2,3
• Intravenous

Question 9

What is the Sabin vaccine?

Answer 9

• Licensed 1962
• Contains live but attenuated strains of poliovirus type 1,2,3
• Oral

Question 10

What is latency?

Answer 10

Lying dormant or hidden until circumstances are suitable for development of infection e.g herpes virus- cold sore

Question 11

What is reverse transcription?

Answer 11

Copying of an RNA template (the viral genome) into a double stranded DNA copy

Question 12

What is integration?

Answer 12

Insertion of the viral cDNA into the genome of the infected cell, to form the provirus

Question 13

What is a consequence of integration?

Answer 13

An infected cell can not be cured of a retroviral infection other than be killing that cell
This makes it impossible to eradicate an infected animal of a retroviral infection