Hence, various enzymes may catalyze distinct stages of an infection, resulting in the production of H2S. In this study, gene and protein expression results indicated that CSE expression fluctuation was stronger compared to CBS and MPST in infected cells, suggesting that CSE is a major H2S producer in macrophages during E. coli infection, particularly in 5 h infection. The gene discussed is CBS; the disease is escherichia coli infection.