86 F. B. BANG 



virus have been seen deep in the cell, whether the cell responds with a pro- 

 fusion of filaments or by complete disintegration. 



There are numbers of studies of the effects of these viruses on both un- 

 differentiated and specialized cells. It would be gratifying to be able to plot 

 these in an orderly pattern which could be the key as to how and where virus 

 is synthesized. Unfortunately, this again would be premature, for virus 

 strains, cell types, and methods of study have all varied so much that 

 generalizations based primarily on morphology would rather confuse than 

 clarify the question. The remainder of this section therefore will review 

 studies on particular virus species in relation to the method of study rather 

 than in relation to the host cell. 



C. Living Cells 



Although the gross destructive effect of virus on certain cells is readily 

 observed in tissue culture (Bang and Gey, 1951; Bankowski and Hyde, 1957; 

 Tyrrell, 1955), there have been few studies on the living system either by the 

 standard higher magnifications or by the improved resolution of phase 

 microscopy. Exceptions are the study of Flewett and Challice on fowl plague 

 (1951), in which phase microscopy clearly shows the development of nuclear 

 masses which broke down as the cell disintegrated, and the study of Henle 

 el al. (1954), who followed the formation of false giant cells infected with 

 mumps virus and caused by an early lysis of the cytoplasm of small clumps 

 of cells. The boundary between the cells then disappeared and only later did 

 the nuclei disappear. 



D. Fixed Tissues 



The destructive effect of influenza virus on ciliated epithelium is well 

 known. The virus, however, is not invariably destructive (Harford and Hamlin, 

 1952), and destruction, when it does occur, may be preceded or accompanied 

 by certain cytoplasmic inclusions (Mount, 1951; Harford and Hamlin, 1952). 

 The cytoplasmic inclusions in parotid glands with mumps (Johnson and 

 Goodpasture, 1936) may be similar but also may be reaction to injection 

 (Bloch, 1937). Thus, the recent studies of Wolff (1957) are important but 

 difficult to relate to previous work. By microspectrophotometry of appropri- 

 ately stained material (Feulgen for DNA and periodic acid Schiff 's for glyco- 

 protein), he was able to follow the amounts of these substances at intervals 

 after infection. The mouse-adapted strain of influenza A(WS) consistently 

 lowered the amount of glycoprotein in the cytoplasm of bronchial epithelial 

 cells during the first 6 hours of infection. Active virus accomplished this, but 

 heat-inactivated virus produced no change. The DNA content of these same 

 cells was decreased with active infection during the first 7-J hours and then 



