Historical perspective

In the course of studying viruses, we have made progress in understanding the complexities of virus disease through knowledge of virus structure, replication, and host interactions. Virus research has  also  extended our  understanding of the  fundamentals of cell biology,  providing insights into  aspects such as mRNA splicing and  protein translation, protein–protein interactions, the  structure and  functioning of the  cytoskeleton, RNA interference, and  the  mechanisms of the  immune system. Few of these studies would have been possible without the means of propagating viruses outside their normal hosts. This requires the ability of a virus to replicate within host cells that are themselves grown in laboratory vessels in nutrient solutions. It is worth remembering that viruses do not ‘grow’ in the way cells do; they replicate. For the purposes of this section, the processes that allow cells to be cultured will be referred to as cellular mitosis or division and the processes that allow the production of new virus (through replication in cultured cells) will be referred to as virus propagation or amplification. Cell culture (often called  tissue culture) requires an environment in which the cells are provided with suitable nutrients and  other conditions (e.g. oxygen,  salts,  support, space, etc.) that promote steady, regular, and  continuous mitosis, achieving a doubling of cell numbers at a predictable rate. This was first achieved in the  late  19th  century for a number of bacteria, following the development of simple broths or media containing a few salts  and  sugars, but  for eukaryotic cells  the  development of suitable media able  to support continued mitosis in vitro did not occur until the early 1950s.

Consequently early virus research was limited to bacteriophages, with an upsurge in the study of eukaryotic viruses in the last 60 years. The culture of eukaryotic cells (specifically, of animal cells) and their support of eukaryotic virus replication is the focus of this section.There are over 3000 characterized cell lines derived from many diverse species that are kept in, for example, the American Type Culture Collection and the European Collection of Animal Cell Cultures.