Virus, inactivation reproduction

The temperate virus does not exist in its mature, infectious state inside the cell, but rather in a latent form, called the provirus or prophage state. In considering virulent viruses we learned that the DNA of the virulent virus contains information for the synthesis of a number of enzymes and other proteins essential to virus reproduction. The prophage of the temperate virus carries similar information, but in the lysogenic cell this information remains dormant because the expression of the virus genes is blocked through the action of a specific repressor coded for by the virus. As a result of a genetic switch, the repressor is inactivated, virus reproduction occurs, the cell lyses, and virus particles are released. 

Kethoxal, 3-ethoxy-2-oxobutanal hydrate [CH3. CH(OEt).CO.CH-(OH) ] was the first substance, selectively, to inactivate complete virions, namely those causing Newcastle bird disease and influenza tested in embryonated eggs (Tiffany et al, 1957). 2-Thiouracil 12,44) a potent inhibitor of the reproduction of plant viruses, also decreases the infectivity of poliovirus by reaction with a mercapto-group in the capsid (Steele and Black, 1967). However agents such as these which act on the complete virion have not yet proved clinically successful. 

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