What is a Virus? What are Viruses made up of ?

8. How are Viruses Studied?

Viruses are much harder to isolate and grow in the lab than other microorganisms such as bacteria or fungi. This is because viruses need to be grown inside an appropriate host cell and maintaining cultures of host cells requires much technical skill. Furthermore, whereas bacterial ands fungal cells can be observed using light microscopy, such is the small size of viruses that powerful transmission electron microscopes are needed to see them. There are several different virus classification schemes. Initially these schemes were based on comparison of virus shape and size, or the types of cells that they infect, but today viruses are classified according to their genomes, and their great diversity has required the description of over 250 different families to accommodate them.