ABSTRACT
Before the discovery of virus particles, they were identified on the basis of their biological properties, particularly symptoms, host range, transmission and physical properties of the infectious sap. Viruses used to be denoted by the common name of their main host, or the host on which they were fi rst identified, and the common term specifying the symptoms, as for example Tobacco mosaic, Tobacco ring-spot, Tobacco leaf-curl, Aster yellows, Rice dwarf, Banana bunchy-top etc. Th ese approaches for identifying and naming a virus served a useful purpose but led to immense confusion and controversies. Th e same virus can infect many diff erent hosts and produce diff erent symptoms, and a single host may be infected by many viruses that produce diff erent symptoms and is known by diff erent names. Tobacco mosaic virus (TMV) produces mosaic symptoms in many plants and is recorded by a large number of diff erent names, for example Tomato mosaic when it infects a tomato and Brinjal streak mosaic when it infects a brinjal. Tobacco mosaic virus and Cucumber mosaic virus produce typical mosaic symptoms in tobacco and cucumber respectively. When they simultaneously infect cucumber plants, an altogether diff erent symptom appears in leaves which become horseshoe shaped. So naming a virus and virus nomenclature was, and remains, a serious concern.
