CHAPTER XI 

 Virological Methods 



Albert P. McKee 



INTRODUCTORY 



While the reading knowledge of the virologist is usually sufficiently 

 broad to include the viruses attacking higher plants, animals, and man, 

 the bacterial viruses or bacteriophages, and the rickettsiae, his area of 

 laboratory concentration is usually more definitive. Certain fringe areas 

 cannot be ignored by the virologist. Some similarities between enzymes 

 and viruses exist, though the enzymes seem unable to reproduce them- 

 selves. On the other hand, pleuropneumonia organisms may be very 

 small and filterable and possess a growth cycle, as do some of the viruses, 

 though they can be grown apart from living cells. 



To the extent that viruses and their behavior are similar to other 

 microorganisms and their behavior, we may draw upon knowledge about 

 a vast group of organisms to help us understand the viruses. In such 

 instances as they differ, we must, if we are to succeed, improvise and 

 develop new methods to serve the peculiarities of virology. 



Viruses and rickettsiae may be studied along similar lines to the bac- 

 teria, tliough the areas of emphasis and knowledge are in some respects 

 quite different. The conventional approaches of studying morphology, 

 cultural characteristics, physiology, serology, and pathogenicity used in 

 bacteriology can be applied only partially to virology. Since intensive 

 study of virology is relatively recent, technical knowledge changes almost 

 daily. No attempt is made in this discussion to report the very latest 

 technics, nor will all available technics or modifications be treated. 



Since viruses vary tremendously in the host cells they attack (from 

 bacteria to man), in size (from near molecular to bacterial), and in many 

 other respects, generalizations and analogies must be used with caution. 

 The technics that may work well with one virus may fail miserably with 

 another. Standardization of methodology has some advantages and 

 some drawbacks. Standard methods not uncommonly discourage 



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