In vitro Larval Invasion Assay

Normal mouse intestinal epithelial cells (IECs) were previously isolated from BALB/c mouse intestines and maintained for the in vitro larval invasion assay [29 (link)]. Investigations revealed that the IECs were susceptible to larval invasion of T. spiralis, in contrast to C2C12 cells from mouse striated muscle myoblasts, which were resistant to larval invasion. IECs were used in the in vitro larval invasion assay, and C2C12 cells were used as a negative control. IECs and C2C12 cells were cultured in 25 cm² cell culture flasks (Corning, NY, USA) in Dulbecco’s modified Eagle’s medium (DMEM) (Solarbio, Beijing, China) supplemented with 5% foetal bovine serum (FBS) (Solarbio, China) and incubated in 5% CO₂ at 37 °C. To maintain the cell cultures, the medium was renewed every 2 or 3 days, and cell monolayers were digested with 0.25% trypsin (Solarbio, China). Preparation of proteins from IEC and C2C12 lysates was performed as described above [31 (link)].