Chapter 16 - Biological Knowledge In Response To Disease

Question 1

1. Define pandemic + list conditions
2. Define epidemic
3. Define endemic
4. Define outbreak

Answer 1

1. Pandemic = global outbreak of disease. Refers to the spread of disease not the severity of the disease.
   Conditions:
   • new pathogen
   • no immunity
   • causes illness
   • transmitted easily - airborne, blood, vectors.
   • uncontrolled spread
2. Epidemic = widespread occurrence of an infection disease in a community or in a restricted geographic area at a particular time. Can turn into pandemic.
3. Endemic = diseases present at constant low levels in a population or region known.
4. Outbreak = a sudden increase in the prevalence of a particular disease.

Question 2

Influenza: how does it change?

• Influenza: single-stranded RNA

Answer 2

1. Antigenic drift = small changes occur - single point mutations that occur gradually until at some point in time a new subtype/strain occurs that a person’s system can no longer recognise.
2. Antigenic shift = re-assortment of RNA segments from two or more different virus subtypes. Sudden appearance of a new subtype/strain no longer recognised.

Question 3

Rational drug design

Answer 3

The active site of a molecule (enzyme) is determined and a second molecule (the drug) is constructed to fit into that active site to inhibit the activity of the first molecule.

Question 4

Influenza + Relenza

1. Influenza surrounded by?
2. What is relenza?
3. Relenza absent/present

Answer 4

1. The influenza virus is surrounded by H and N spikes.
2. Relenza (generic: zanamivir) = anti-flu drug, neuraminidase inhibitor.
3. • Relenza absent: virus enters a cell, takes control. Viral parts synthesised using host cell, moves to surface of the cell and ‘buds’ out of the membrane, then exits the cell. Newly synthesised viruses stay on the surface of the cell until neuraminidase triggers virus release by cutting the attachment between the cell and virus. Viruses are then free to infect other cells.
   • Relenza present: Relenza binds to neuraminidase active site. Therefore, the new viruses are trapped at the surface of the infected cell. The cell can then be destroyed by the immune system.

Question 5

• 3 methods of identifying pathogens?
• 3 methods used to detect bacteria?

*Epidemic Intelligence Service (EIS)

Answer 5

• identifying pathogens:

1. Physical methods: X-ray crystallography, electron microscope.
2. Immunological methods: ELISA technique (Enzyme-Linked ImmunoSorbent Assay) - detects antibodies to specific viral diseases in cells or body fluids.
3. Molecular techniques: DNA probs to detect and locate specific genetic sequences to a particular virus.

• detecting bacteria

1. Phenotypical methods: microscopes, staining, various testing.
2. Immunological methods: monoclonal antibodies, ELISA, immunofluorescence.
3. Genotypes and molecular methods: gene probes, sequence analysis.

Question 6

Antibiotics

What?
Role?
Narrow spectrum
Broad spectrum

Answer 6

Antibiotics = antimicrobial drug used in the treatment and prevention of bacterial infection - do NOT work on viral infections.

Role = kill or inhibit bacterial growth, interfere with binary fission, inhibit protein synthesis or enzyme activity.

Question 7

Antiviral drugs

What?
Use?

Answer 7

• specific for treating viral infections.
• particular use for HIV/AIDS - can block entry into host cell, interfere with DNA replication, block enzymes, inhibit neuraminidase, (responsible for new viruses to be released).
• monoclonal antibodies as viral agents are being designed.