To overcome weakness and faults of a web-based e-learning course such as Artificial Intelligence (AI), an immune agent was proposed, simulating a natural immune mechanism against a virus. The immune agent was built on the multi-dimension education agent model and immune algorithm. The web-based AI course was comprised of many files, such as HTML pages, JSPs, Java applets, and JavaScript programs. The immune agent was used to detect, recognize, eliminate, and repair the virus and faults of the AI course. The model, characteristics and algorithm of the immune agent were proposed and analyzed. The simulation example of the web-based AI course shows that the immune agent can detect some viruses and faults, recognize and eliminate the viruses and faults, and repair the e-learning system, keeping the e-learning system normal and robust.