Abortive Infection: Bacterial Suicide as an Antiviral Immune Strategy

Facing frequent phage challenges, bacteria have evolved numerous mechanisms to resist phage infection. A commonly used phage resistance strategy is abortive infection (Abi), in which the infected cell commits suicide before the phage can complete its replication cycle. Abi prevents the phage epidemic from spreading to nearby cells, thus protecting the bacterial colony. The Abi strategy is manifested by a plethora of mechanistically diverse defense systems that are abundant in bacterial genomes. In turn, phages have developed equally diverse mechanisms to overcome bacterial Abi. This review summarizes the current knowledge on bacterial defense via cell suicide. It describes the principles of Abi, details how these principles are implemented in a variety of natural defense systems, and discusses phage counter-defense mechanisms.