ENVIRONMENTAL BIOTECHNOLOGY Environmental Virology – Revision questions

1. The infective dose of enteric viruses is typically

A. 1 virus particle B. 10-100 virus particles C. 100-1000 virus particles D. >1000 virus particles

2. Which of the following viruses enters via the oral route but does not cause

gastroenteritis

A. Norovirus B. Poliovirus C. Rotavirus D. Astrovirus

3. In the oceans, viruses have been estimated to be present at levels of up to

A. 103 particles/mL B. 106 particles/mL C. 109 particles/mL D. 1012 particles/mL

4. Name THREE (3) of the groups of enteric viruses commonly investigated as

contaminants in water. Give an example of ONE (1) virus found in each of the groups you have named.

5. Outline THREE (3) reasons why viruses are good indicators of water quality.

6. The final step in the concentration of viruses from environmental water

samples is to further reduce the volume of the sample to 1-2 mL prior to analysis. Two methods commonly used to do this are organic flocculation and polyethylene glycol precipitation. Briefly describe these procedures.

7. What are the advantages and disadvantages of using conventional

polymerase chain reaction (PCR) to detect viruses in water samples? Name and briefly describe TWO (2) of the modified PCR methods that can be used to overcome any of the disadvantages of conventional PCR.