BIOLOGICAL ASPECTS OF INTRACELLULAR STAGES OF VIRUS GROWTH 123 



is situated in an extracellular or an intracellular position at the time the cell 

 extract is prepared for virus assay. The experimental method most commonly 

 used to answer this question has been to find the effect of treating the cells 

 with viral antiserum on the amount of virus recoverable after disrupting the 

 cells. There is, however, a possible objection to this technique, that antibody 

 might first combine with extracellularly situated virus, and, if bivalent, later 

 combine also with intracellular virus when the cells are disrupted. Efficient 

 removal of the antibody by washing is therefore an essential part of the 

 teclmique, and if it is shown that treating control cells with antiserum after 

 infection has been initiated does not reduce the final yield of virus from these 

 cells, this can be taken as evidence that the antibody has not had much 

 influence on the titer of intracellular virus. Two other types of experiment 

 have also been carried out to test the localization of recoverable virus, i.e., 

 treating the cells with RDE in the case of influenzal infection, and repeated 

 washing of cells to see what is the effect on the amount of virus recoverable 

 during the lag period. . 



Andrewes (1930) first showed that the growth of herpes simplex virus in 

 tissue culture was not inhibited by viral antiserum inoculated after the 

 initiation of infection. The effect of antiserum used in this way on the recovery 

 of virus during the lag period has been studied by a number of workers. 

 Henle and Henle (1949) noted that antibody given 30 minutes after a large 

 inoculum of influenza virus (10 9 LD 50 ) in the chick allantoic cavity reduced 

 the recovery of virus in the membranes during the lag period by 3 log 10 , 

 without reducing the eventual yield of infective virus in control eggs similarly 

 inoculated. Apparently, too, antibody was not fixed by uninocuiated mem- 

 branes. On the other hand, antibody reduced the yield of virus after a small 

 inoculum, suggesting that some multivalent antibody combined with 

 superficially absorbed virus and was then carried over into the tissue on 

 extraction. It is best, therefore, as Henle and Henle point out, to accept the 

 findings as giving qualitative evidence that a substantial part of the recover- 

 able virus is superficially attached to the cells, without attempting to interpret 

 the findings on a strictly quantitative basis. In essentially similar experiments, 

 Schafer and Munk (1952) found that the recovery of fowl plague virus from 

 the membrane was reduced by 3-4 log 10 by treatment with antiserum; 

 Tamm and Tyrrell (1954) and Ackermann and associates (1955) found a 

 1 log 10 reduction with influenza virus grown in pieces of chorioallantoic 

 membrane in vitro; and Ishida and Ackermann (1956), while investigating 

 the effect of temperature on the fixation of virus to cells, noted that immune 

 serum treatment caused a large reduction in the recovery of influenza virus 

 after adsorption to membranes at 3°C. However, the latter workers also 

 obtained, in the same way as Henle and Henle (1949) had done, results 

 which suggested that in their experiments some serum becomes bound to the 



