Infectious Disease Online
List of Viruses and Viral Diseases
Viruses are obligate intracellular organism, contain DNA or RNA within a cylindrical or spherical protein coat or capsid, which may be surrounded by a lipid bilayer (envelope).
Viruses are organisms that can be characterized as having two distinct phases in their life cycle - an intracellular and an extracellular phase.
Intracellular phase is the replicative phase during which the virus multiplies in the infected cell.
There it borrows the metabolic machinery of the cell to direct the synthesis of proteins coded by the viral genome.
The structural and nonstructural virion components are synthesized independently, and the structural proteins are assembled into whole virions during the final stage of reproduction.
When virions leave the cell, they are particles of uniform size, shape and chemical composition that in some cases can crystallize.
This is the extracellular phase of the virus.
The viral particles can initiate the infectious process of new cells, and hence they constitute the infectious form of the virus.
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