CRISPR/Cas9-Induced Knockout of Increases Susceptibility of Zebrafish to Bacterial Infection.

Stimulator of interferon genes (STING) is an adapter protein that is activated when cyclic dinucleotides (CDNs) are present. CDNs originate from the cytosolic DNA of both pathogens and hosts. STING activation promotes efficient immune responses against viral infections; however, its impact in bacterial infections is unclear. In this study, we investigated the role of Sting in bacterial infections by successfully creating a -deficient ( with a 4-bp deletion) knockout zebrafish model using CRISPR/Cas9. The transcriptional modulation of genes downstream of cGAS (cyclic GMP-AMP synthase)-Sting pathway-related genes was analyzed in seven-day-old wild-type (WT) and embryos, as well as in four-day-old LPS-stimulated embryos. The expression of downstream genes was higher in than in healthy WT fish. The late response was observed in larvae following LPS treatment, demonstrating the importance of Sting-induced immunity during bacterial infection by activating the cGAS-STING pathway. Furthermore, adult fish had a high mortality rate and significantly downregulated cGAS-STING pathway-related genes during () infection. In addition, we assessed NF-κB pathway genes following infection. Our results show fluctuating patterns of ( and ( expression, which is likely due to the influence of other NF-κB pathway-related immune genes. In summary, this study demonstrates the important role of Sting against bacterial infection.