Abstract:The toxin-antitoxin (TA) system is ubiquitous in bacteria and archaea. A typical TA system generally consists of a toxin that inhibits bacterial growth and an antitoxin that neutralizes toxin toxicity. At present, TA systems are classified into types I-VIII, of which type II system is the most extensively studied. In addition, researchers have found that there are atypical TA systems such as monocistronic TA systems and three-component TA systems. After the discovery of the first TA system (CcdB/CcdA) in the 1980s, TA systems have been shown to play a key role in the physiological processes of microorganisms. In this paper, we review the research results about the roles of TA systems in resisting bacteriophage infections in recent years and summarize the neutralization mechanisms. In particular, we brief how TA systems specifically sense the invading bacteriophages and the underlying molecular mechanisms, aiming to provide reference for the research on the roles and regulation mechanisms of unknown TA systems in the future.