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. 10 3 particles/mL B. 10 6 particles/mL C. 10 9 particles/mL D. 10 12 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.