Lesson 3: Strategies for Cultivation of Viruses

• Because viruses are obligate intracellular parasites, they cannot be grown on any inanimate traditional medium or a man-made nutrient medium.
• They require a dwelling host cell for replication.
• Contaminated host cells (eukaryotic or prokaryotic) will be cultured and grown, after which the expansion medium will be harvested as a supply of the virus.
• Virions within the liquid medium can be separated from the host cells by either centrifugation or filtration.
• Filters can physically remove anything present in the solution that is larger than the virions; the viruses can then be collected in the filtrate (see Figure below).

• Bacteriophages will be grown within the presence of a dense layer of micro organism (additionally known as a bacterial garden) grown in a 0.7 % smooth agar in a Petri dish or flat (horizontal) flask
• Typically,  three strategies are employed for the virus cultivation

1. Inoculation of the virus into animals
2. Inoculation of the virus into embryonated eggs
3. Virus propagation in tissue or cell tradition

Goal of virus cultivation

• The first functions of viral cultivation are:

1. To isolate and establish viruses in scientific specimens
2. To organize viruses for vaccines
3. To do detailed analysis on the viral construction, multiplication cycles, genetics, and results on host cells