b« F. B. BANG 



nasal washings (Liu, 1956), and by others to follow the development of so- 

 called incomplete virus in ascites tumor cells (Prince and Ginsberg, 1957). 



1. Mumps 



The first of these studies (Watson, 1952) on mumps in chick embryos 

 showed that mumps antigen was present in those cells in contact with the 

 amniotic fluid (embryos inoculated intra-amniotically), such as amniotic, 

 epidermal, and pharyngeal epithelium. It was subsequently found in the 

 gastrointestinal and respiratory tracts and in an acellular horny layer. The 

 antigen appeared as bright intracytoplasmic granules. Electron microscopy 

 of chick embryo allantoic infection with this virus shows surface changes only 

 on the allantoic cells (Bang and Isaacs, 1957). 



2. Influenza 



Influenza virus (PR8 and LEE B) in the amniotic sac also apparently 

 localized in cells lining the amnion, and in epidermal and pharyngeal epi- 

 thelium. Specific staining appeared when the amniotic fluid contained 4.5 

 LD 50 log of virus. Watson and Coons (1954) suggest that the antigen is first 

 detectable in the nuclei or around the nuclear membrane, and that it then 

 appears in the cytoplasm. In one pair of pictures, in which a slide previously 

 stained with fluorescein was restained with hematoxylin, the nuclear or peri- 

 nuclear localization of the antigen seems clear. 



The histological localization of influenza virus in ferret epithelium is 

 clearly shown by Liu (1955a), who was able to follow the progress of the 

 infection, including desquamation of epithelium and uptake of viral antigen 

 by macrophages. The presence of viral antigen was demonstrated in the 

 cytoplasm and ciliated border of the epithelial cells. Several pictures show 

 numerous, large, fluorescent, intracellular masses which appear to be the 

 individual nuclei of the epithelial cells. In a separate study of this, Liu 

 (1955b) finds that the fluorescence, which he believes to be nuclear, was 

 responsible for the cross-fluorescent staining reactions among the three 

 strains of A virus studied, and that absorption of the antisera with the V 

 and S antigens indicated that the S antigen was responsible for the nuclear 

 fluorescence. Since the large intracytoplasmic inclusions in the mouse bron- 

 chus were thought to be virus, and since ferret cells destroyed by influenza 

 are apparently phagocytyzed by neighboring cells (Hotz and Bang, 1957a), 

 the masses of fluorescent antigen need to be differentiated from possible 

 phagocytized material. 



3. Fowl Plague 



The intranuclear localization of the "G antigen," or bound antigen of fowl 

 plague, which is closely related to influenza, was determined by Breitenfeld 



