When a host bacterium (Pseudomonas solanacearum E. F. Smith strain S) is mixedly infected with SP1 and SP1h1 viruses (the host range mutant of SP1 virus), the interference phenomena can be detected. These phenomena were investigated under various conditions and the results were as follows; 1. If the bacterial cell was infected simultaneously with both viruses of same proportion, the yield contained the same size of particles belonging to both types. 2. If, between the infecting particles, the proportion of one type was considerably reduced, the growth of this type was much reduced. 3. If the bacterial cell was infected with the one type earlier than the other, the growth of the latter was reduced, and the reduction could never be restored by the increase of infecting particles of the latter. 4. The partially inactivated virus by ultraviolet irradiat ion, interfered also in the growth of active same type one, as SP1 virus interfered in SP1h1 virus or vice versa. But if the active virus was given ahead of the inactivated one, the growth of active one was normal. 5. The partially inactivated SP1 virus was reactivated by the mixed infec tion with active SP1h1 virus.
1. Pseudomonas solanacearum E. F. Smith S株にSP1及びSP1h1の両バイラスが混合感染する場合, 寄主細菌は両バイラスを放出する. 但し感染時に数量的に優性をしめしたバイラス, 或は時間的により早く感染したバイラスは, 然らざるものの増殖に干渉し, その増殖を低下せしめる. 2. 活性SP1バイラスと紫外線照射による不活性SP1バイラスとの混合感染の場合, 両者の間には干渉現象が起り, 前者の増殖は低下する. 3. 紫外線照射による不活性SP1バイラスは, 活性SP1h1バイラスの感染によつて賦活化される.