Abstract
Methods of propagating Newcastle disease virus in rocking, rolling and medium-changing cultures with adult chicken spleen were studied in comparison with the conventional static culture method. The main results are as follows.
1. Rocking effected no better results in the propagation of the virus.
2. Rolloing made the end titer of the virus a little higher.
3. The change of medium resulted in a remarkable increase of the end titer of the virus. Especially it was true in rolling cultures with relatively high concentration of tissue.
4. Throughout the whole study, the culture method most fitted for virus propagation was found to consist of the following steps. The tissue weighing 10 per cent of the amount of culture medium was fixed on a piece of Japanese rice paper and placed in a culture tube or bottle with cotton plug. The culture was made under conitnuous rolling, and the medium was renewed twice a day. By this method LD50 titer (-log10) reached 7.5 in whole culture and 8.5 in cultured tissue.
