Although we used a brain organoid system instead of a mouse infection model because M. fermentans did not induce toll-like receptor 4 (TLR4)-mediated interferon-induced transmembrane protein 3 (IFITM3) upregulation and necrotic cell death in mouse neuronal cells, our cerebral organoid model system clearly supports M. fermentans infection-mediated necrotic neuronal cell death. The gene discussed is TLR4; the disease is infection.