Disclosed herein are compositions comprising one or more therapeutic proteins for oral administration. The disclosed proteins, which may be directed to a variety of GI and systemic target antigens, resist denaturation and degradation in the stomach and intestines of a patient. The disclosed proteins may be delivered intact to a target region within the gut, or anywhere in body to target specific molecules, cells, tissues, or organs. In some embodiments, the disclosed proteins may include two or more proteins for targeting two or more target antigens.