Culturing viruses in the laboratory

Now that you know what is cell culture and the importance of it, this section will be about culturing viruses.

Viruses must be cultured in order to conduct research and develop vaccines and treatments, but because viruses cannot metabolize or replicate by themselves, they cannot be grown in standard microbiological broths or on agar plates thus they have be to cultured inside suitbale host cells , a requirement that complicates the detection, identification and characterization of viruses.
Virologist have developed 3 types of media for culturing viruses.

First , culturing viruses in bacteria.

Most of our knowledge of viral replication has come from research on bacteriophages.
which is quite easy to culture because bacteria are easily grown and maintained. Phages can be grown in bacteria maintained in either liquid or on agar plates.
Bacteria and phages are mixed with warm nutirents agar and poured in a thin layer across the surface of an agar plate. during incubation , bacteria infected by phages lyse and release new phages that infects nearby bacteria while uninfected bacteria grow and reproduce normally.
After incubation,the appearance of the plate includes a uniform bacterial lawn interrupted by clear zones called plagues. Which are areas where pahges have lysed the bacteria. Such plates enable the estimation of phage numbers via a technique called plaque assay in which each plaque corresponds to a single phage in the original bacterium or virus mixture.

second , culturing viruses in plants and animals.

most experiments designed to study diseases processes and immune responses.Frist discovery and isolation of virus was the discovery of tobacco mosaic vius in tobacco plants.Viruses that infect only humans raises additional ehtical complications.therefore scientists have developed alternative ways of culturing animal and human viruses using fertilized chicken eggs or cell cultures.


Third, cultuing viruses in embryonated chicken eggs

Chicken eggs are useful cutlure medium for viruses because they are inexpensive and among the largest of cells free of contaminating microbes.the yolk is nourishing which is suitbale for viruses to grow in.
So viruses are injected ionto embryonated eggs at the sites that are best suited for the virus's maintenance and replication.
Vaccines against some viruses can be also prepared in egg cultures.