Virus Structure and Classification

Viruses come in a variety of shapes and sizes, but they are the same and different for each virus family. In general, the morphology of the virus is divided into four groups: filamentous, isometric (or icosahedron), envelope, and head and tail. Filamentous viruses are long and cylindrical. Many plant viruses, including TMV (tobacco mosaic virus), are filamentous. Isometric viruses, like poliovirus and herpesvirus, are almost spherical. Envelope viruses have a membrane that surrounds the capsid. Animal viruses such as HIV often have an envelope. The head and tail viruses infect bacteria. It has a head shape resembling an icosahedron virus and a tail shape resembling a filamentous virus. Many viruses use certain glycoproteins to attach to host cells via molecules on the cell called viral receptors. For these viruses, attachment is a prerequisite for later penetration into the cell membrane so that replication can be completed within the cell. Receptors used by viruses are molecules normally found on the cell surface and have unique physiological functions. The virus has only evolved to use these molecules for its own replication.

Related associations and societies

Canadian Society for Virology, German Society for Virology, Italian Society for Virology, Spanish Society for Virology, American Society for Virology, Australasian Virology Society, Max Planck Society, Brazilian Society for Virology, Swedish Society for Virology, Viruses: National Multiple Sclerosis Society, Infectious Diseases Society of America.


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