A 9-month-old infant from a resource-poor country presents with persistent watery diarrhea and malnutrition. An intestinal biopsy reveals blunting of the villi and a characteristic histopathologic lesion where bacteria are intimately attached to the epithelial surface, causing effacement of the host cell microvilli. This “attaching and effacing” lesion is primarily mediated by the binding interaction between which two bacterial protein factors?