Direct mechanical stimulation triggers hatching in Trichuris suis eggs.

Hatching of Trichuris suis eggs within the host intestine is essential for the establishment of infection; however, the mechanisms underlying its induction remain incompletely understood. Although previous studies have suggested the involvement of intestinal microbiota and chemical factors, the contribution of physical cues has not been systematically examined. In the present study, we employed an in vitro hatching system to investigate the environmental signals required for egg hatching. Under host body temperature conditions (38 °C), hatching was not induced in the absence of physical stimulation. In contrast, specific mechanical stimuli that directly act on the egg membrane, such as agitation with glass beads or ultrasonic treatment, effectively induced hatching. Mechanical stimulation associated with fluid flow did not trigger hatching. Moreover, weakening of the eggshell by sodium hypochlorite treatment enhanced the sensitivity of eggs to mechanical stimulation, suggesting that the eggshell functions as a protective barrier against external physical stress. Direct local compression of the egg membrane using a blunt glass needle also induced hatching, indicating that localized mechanical deformation of the egg membrane serves as the hatching trigger. This study provides experimental evidence for the critical role of physical stimulation in whipworm egg hatching and offers a new perspective on the mechanisms underlying whipworm infection establishment.