Cell cultures virus cultivation

With animal viruses, the initial host may be a whole animal which is susceptible to the virus, but for research purposes it is desirable to have a more convenient host. Many animal viruses can be cultivated in tissue or cell cultures, and the use of such cultures has enormously facilitated research on animal viruses. 

Classification of animal viruses Most of the animal viruses which have been studied in any detail have been those which have been amenable to cultivation in cell cultures. As seen, animal viruses are known with either single-stranded or doublestranded DNA or RNA. Some animal viruses are enveloped, others are naked. Size varies greatly, from those large enough to be just visible in the light microscope, to those so tiny that they are hard to see well even in the electron microscope. In the following sections, we will discuss characteristics and manner of multiplication of some of the most important and best-studied animal viruses. 

Cell culture is the predominant and indispensable tool for virus isolation and cultivation infectivity assays and vaccine production and testing. Although some viruses are more easily isolated in animals and embryonated eggs, the modem era of virology only began when Enders et al. (1949) showed that poliovirus was able to reproduce in various kinds of human embryonic cells in culture whereas in vivo its multiplication is largely restricted to the neurons in the grey column of the spinal cord. 

Analysis of waters for viruses is more difficult because of their small size, about 10 to 300 nm average diameter. Also, viruses need susceptible living cells such as chick embryos or tissue cultures for cultivation and identification in the laboratory, which make them more difficult to work with. Nevertheless, viruses represent an important microbiological class for water and wastewater-monitoring programs since serious waterborne diseases such as polio and hepatitis are transmitted in this way. 

Future cultivation methods will resemble existing methods of microbial and virus culture. Ill-defined medium components and cells will be replaced to enhance reproducibflity in production. For bacterial and ex vivo cultivated virus, analytical advances will make monitoring the environment and nutritional status of the culture more ubiquitous. However, the major changes will be in novel product types — single-molecule subunit antigens, viras-hke particles, monoclonal antibodies, and gene-therapy vaccines, each of which will incorporate novel processes. 

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