Viral Replication
Viral replication refers to the propagation of biological viruses in the host cells during infection. The term usually refers to the replication of large numbers of viral genomes-the genetic material of the virus. The genome is reproduced by an enzyme which is called the viral replicase.

Model Organisms and Model Viruses
Biologists work with a number of model organisms (also called model systems) that are thoroughly studied, have relatively short life-cycles, have well-characterized genetic material, and are easy to maintain, reproduce and manipulate in laboratory settings.

Examples of animal model organisms include mice, zebrafish, and fruit flies.

In plants, the genus Arabidopsis has proven quite useful as a model organism. Techniques have been developed that allow genetic manipulation of this plant, including knockout or alteration of specific genes.

The Tobacco Mosaic Virus (TMV) is often used as a model for plant viruses. TMV can be genetically manipulated in various ways, and can be used as a means of introducing new or altered genes into plants.