Cell culture is the most widely used method for the propagation of viruses. They are convenient, economical, observable cytopathic effects and choice of cells for their susceptibility to a particular virus. Depending on the basis of origin and characteristics, cell cultures are of three types:
Primary cell cultures: They are derived from normal tissue of an animal such as mouse, chicken, hamster or monkey tissue. When cells from these tissues are processed and cultured, the first monolayer is referred to as Primary culture. The cells from subcultures as referred to as Secondary cultures.
Diploid cell strains: They are derived from primary cell cultures developed from a particular type of tissue such as kidney or lung, which is of embryonic origin. Such diploid cell stains are the host for many viral studies and research. They are of a single cell type and can undergo at least 100 divisions before dying.
Continuous cell lines: They are capable of infinite number of doublings. These cell lines arise with mutation of a cell strain or from the establishment of cell cultures from malignant tissue.