Recently, virtual staining technology has greatly promoted the advancement of histopathology.Despite the practical successes achieved, the outstanding performance of most virtual staining methods relies on hard-to-obtain paired images in training.In this paper, we propose a method for virtual immunohistochemistry (IHC) staining, named confusion-GAN, which does not require paired images and can achieve comparable performance to supervised algorithms.Specifically, we propose a multi-branch discriminator, which judges if the features of generated images can be embedded into the feature pool of target domain images, to improve the visual quality of generated images.Meanwhile, we also propose a novel patch-level pathological information extractor, which is assisted by multiple instance learning, to ensure pathological consistency during virtual staining.Extensive experiments were conducted on three types of IHC images, including a high-resolution hepatocellular carcinoma immunohistochemical dataset proposed by us. The results demonstrated that our proposed confusion-GAN can generate highly realistic images that are capable of deceiving even experienced pathologists.Furthermore, compared to using H\&E images directly, the downstream diagnosis achieved higher accuracy when using images generated by confusion-GAN.Our dataset and codes will be available at https://github.com/jiahanli2022/confusion-GAN.