General Properties of Viruses-review

General Properties of Viruses-review - General Properties...

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General Properties of Viruses Structure 1. Nucleic acid - Single or double stranded. Segmented or unsegmented Deoxyribonucleic Acid (DNA) Ribonucleic Acid (RNA) 2. Capsid -The capsid accounts for most of the virion mass. It is the protein coat of the virus. It is a complex and highly organized entity which gives form to the virus. Subunits called protomere s aggregate to form capsomeres which in turn aggregate to form the capsid. 3. Envelope -this is an amorphous structure composed of lipid, protein and carbohydrate which lies to the outside of the capsid. It contains a mosaic of antigens from the host and the virus. A naked virus is one without an envelope. 4. Spikes . These are glycoprotein projections that have enzymatic and/or adsorption and/or hemagglutinating activity. They arise from the envelope and are highly antigenic. Morphology (Symmetry) 1. Icosahedral -The protomeres aggregate in groups of five or six to form the capsomere . In electron micrographs, capsomeres are recognized as regularly spaced rings with a central hole. The shape and dimensions of the icosahedron depends on characteristics of its protomeres. All icosahedral capsids have 12 corners each occupied by a penton capsomere and 20 triangular faces, each containing the same number of hexon capsomeres. Icosahedral symmetry is identical to cubic symmetry.
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Replication Cycle 1. Adsorption - It requires the interaction of a unique protein on the surface of the virus with a
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General Properties of Viruses-review - General Properties...

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