Many theories put farwarded regarding the nature of the viruses out of them the viral theory is the most accepted theory.
According to it
- Virus is a granular structure which can not be seen by normal microscope. They can not be isolated by bacterial filter.
- They can not be cultured in artificial (dead) medium.
- They cause specific symptoms in their host cells. They respond to temperature and humidity.
features :
- Nature of Nucleic acid – RNA or DNA
- Symmetry of the capsid (virus)
- Molecular weight of the virus
- Shape and size (Dimensions) of the viruses
- Presence or absence of envelope