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The anatomy of a virus presents a very bizarre picture to many scientists. One, to a taxonomist, a virus may not be tagged living or non-living. Outside a life form, it is not better than any non-living particle around. Inside a life form, a spectacular cell is revealed, quite capable of functioning like any animal cell known. Two, its association with protein bodies, most especially deoxyribonucleic acid(DNA) and ribonucleic acid(RNA) cannot easily suggest it could be the cause of a whole lot of diseases, including Acquired Immunodeficiency Syndrome(AIDS), Borna disease, common cold, chicken pox, bell palsy, Lassa fever, meningitis, mumps, poliomyelitis, influenza, small pox, yellow fever, zoonoses, and rubella. Three, over 5000 types of virus have been elucidated by virologists, a clear pointer to a rather diverse structure of this organism.

Generally, viruses are about 105 times smaller than bacteria and so, a light microscope will not reveal the better part of its morphology. Instead, an electron microscope with scanning and transmission features is used. The following are the four structures common to most species of viruses:

Icosahedral

Icosahedron is a figure with twenty triangular faces. In the morphology of a virus, this figure approximates a sphere and is perhaps the best way to form a closed shell from identical parts repeating itself. The axes of symmetry may be two-fold, three-fold, or five-fold. Most polygonal viruses are icosahedral, and each triangle is equilateral. A rota virus is a very good example of a virus with this structure.

Helical

The discovery of the actual structure of DNA as a double helix in 1953 by James Watson and Francis Crick at Cambridge College, and Maurice Wilkins and Rosalind Franklin at King's College heralded a new hope into the study of virus morphology. A virus with helical structure consists of a single type of capsomers(a morphological unit of the capsid or outer cover of a virus) weaved around a central axis. The central portion may be a hollow tube or a cavity. The tobacco mosaic virus has a helical structure.

Complex

When a virus possess an outer cover which is neither purely helical nor strictly icosahedral, then its morphology is described as complex. A true complex virus will even have more to offer, like a complex outer wall or protein tails. Some bacteriophages have true complex structure. Their complex structure consist of a helical tail linked directly to an icosahedral head. A common feature of the

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