The Enclave Bio-Weapon was a biological contamination device created by the Enclave.
After sending the Hulk to obtain a genetic simulator from the Enclave so that he could test the cure he had developed, Samuel Sterns informed Hulk that Enclave had unleashed a bio-weapon and that this was their chance to do a real-world test of the cure. The contamination enveloped a building in downtown New York City, much to the distress of citizens. The United States Armed Forces arrived to deal with the situation and attacked Hulk when he transported Sterns to the building. While Sterns was inside, Hulk fought the Army. Sterns successfully used the cure on the contamination, destroying it. Hulk then brought Sterns back to Empire State University. Sterns stated the the mission was invigorating and that now they had evidence that the cure worked.