Abstract
A method of propagating Newcastle disease virus in a static culture of adult chicken tissue (spleen) was described in the previous paper. Influence of various conditions for this type of culture upon the virus propagation was further investigated in the present study. The important results are summarized as follows.
1. There was no remarkable difference in final virus titers among cultures using different material, such as Japanese rice paper, filter paper, perforated cellophane, glass surface and agar bed, to fix tissue fragments. Of there materials, Japanese rice paper was the most convenient for practical use.
2. There was no difference in final titers between cultures under anaerobic conditions (using nitrogen) and those under aerobic condition (using air or oxygen). This fact seems to indicate that no oxygen is necessary at least practically, for the multiplication of virus in tissue culture.
3. Rubber stopper or carbon dioxide gas is used usually in culture with a low concentration (below 1%) of tissue. In a culture with a higher concentration (1 to 3%) of tissue, however, the multiplication of virus was more conspicuous when cotton stopper was used. It seemed that the cotton plug served for the discharge of excess carbon dioxide gas which was usually produced in the culture with such a high concentration of tissue and that consequently, it also served to prevent the pH of the medium from unfavorable lowering.
4. The virus propagated in tissue cultures with spleen from a highly immune chicken to almost the same level of virus titer as in those with spleen from a normal chicken.
