4 Classification of viruses

 

Viruses represent one of the most successful types of parasite in the world and have been isolated from representatives of every known group of organisms from the smallest single-celled bacterium to the largest mammal. While in most cases the virus is specific for the host species in which it has been identified, some viruses are able to infect species from different phyla and even different kingdoms. The number of known viruses now reaches over 5000 with new viruses being discovered all the time. This very large number contains a diverse array of viruses which at first sight is very bewildering. To make easier the study of viruses and bring order to this apparent diversity, over the years a number of different systems has been proposed to generate classification schemes which will allow us to study representative viruses rather than each individually. All of the proposed classification schemes have different strengths and weaknesses but there is now general consensus. The International Committee on Taxonomy of Viruses has responsibility for assignment of new viruses to specific groupings.

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