Viral assays allow for quantifying the number of animal viruses. While bacterial viruses can easily be grown, growing animal viruses is more difficult and expensive, often requiring whole animals or embryonating eggs. When animal cells grow as monolayers, a plaque assay can be used to count viruses by serially diluting the virus in a liquid medium and adding it to separate plates with monolayers of tissue culture cells. After the viruses attach, a semi-solid medium is added to restrict virus movement and allow only adjacent cells to become infected, forming visible plaques that can be counted.

1. Viral assay
Dr .Sujit Ghosh
J K College, Purulia

3. Growth of Viruses
While it is easy to grow bacterial viruses, it is much more difficult and expensive to grow
animal viruses
Whole animals
Embryonating eggs (the classic host for vaccine production)

5. When cells grow as monolayers, they can be used to quantify the number of animal
viruses using a plaque assay.
The virus is serially diluted in a liquid medium.
For each dilution a set amount is added to a separate plate containing a monolayer of
tissue culture cells and the viruses in that solution are allowed to attach to the tissue
culture cells.
After attachment has been allowed to occur, a semi-solid medium is added to restrict
the movement of new viruses produced so that only adjacent cells will be infected.