Abstract
Infection with u.v.-inactivated P22 bacteriophage at multiplicities higher than 30 caused a decrease in Salmonella typhimurium viability without cell lysis. Neither the action of the endoglycosidase of the P22 virion on the lipopolysaccharide of S. typhimurium nor the concomitant release of cell wall components was responsible for m.o.i.-dependent cell death. Using both free P22 tails and u.v.-inactivated P22, we have shown that p9 tail protein activity has no effect either on the integrity of host cells or on cell viability. Our results show that cell death is due to the injection of the u.v.-inactivated P22 DNA.