Fig. 1: Standard representation of the role of nucleases in lytic infections.
From: The coordination of anti-phage immunity mechanisms in bacterial cells
A In the absence of infection, the bacterial cell is free from viral DNA and may display basal levels of restriction nucleases capable of cleaving non-self DNA. B In case of infection, the host detects the presence of phage DNA and triggers an innate immune response that includes the upregulation of restriction nucleases. C The balance between the replication of the viral DNA and its destruction by bacterial nucleases determines the eventual outcome of the infection. D If the phage evades the host’s immune response, the bacterial cell dies and releases the newly formed phages to the extracellular space. E Alternatively, the infected cell may undergo suicide to prevent the spread of the infection. F If the host cell survives, it must deactivate its anti-phage defenses and return to the pre-infection state, which involves the downregulation of the nucleases produced during the infection and also the clearance of the remnants of viral DNA from the cytoplasm.
