Describe the techniques in cultivating viruses

1. Using cell (tissue) culture techniques
- Animal cell cultures are grown in sterile chambers with special media that contain the nutrients required by animal cells to survive.
- The cultured cells grow in the form of a monolayer i.e. a single sheet of cells that supports viral multiplication and permits close inspection of culture for signs of infections.
- To detect the growth of a virus in culture, one observes lysis of infected cells in the monolayer of cells. The areas where virus – infected cells have been destroyed show up as a clear, well defined patches in the cell sheet called plaques.
(Plaques are macroscopic manifestation of cytopathic effects)

2. Using bird embryos
Embryo is an early development stage of animals marked by rapid differentiation of cells.
- Birds undergo their embryonic period within the closed protective case of an egg which makes an incubating bird egg a perfect system for viral propagation.
- It has a sterile environment
- Chicken, duck and turkey eggs are the most common choices for inoculation
- The egg is infected through the shell by drilling a hole by sterile techniques.
- The signs of viral growth include – death of the embryo, defects in embryonic development and localized areas of damage in the membrane.
- Embryonic fluids and tissues can be prepared for direct examination with an electron microscope.

3. Using alive animal inoculation
- Specially bred strains of white mice, rats, hamsters’ guinea pigs and rabbits are used for cultivation of animal viruses (insects also used).
- Viruses can exhibit host specificity hence certain animals can propagate a given virus more readily than others.
- Tests can be done on newborn animal, young or adult.
- The animal is exposed to the virus by injection of a viral preparation or specimen into the brain, blood, muscle, body cavity, skin, etc.
- Tissues or fluids are prepared for direct examination under electron microscope.

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Kavungya answered the question on March 12, 2019 at 13:31