Fungal and bacterial pathogens are well capable of infecting plants, animals and humans despite their immune systems. Fungi penetrate leafs, stalks and roots, or skin, intestines and lungs, to infect their hosts. Researchers have now discovered how this is possible. They found that the fungus secretes a protein that makes stray building blocks of the fungal cell wall invisible for the immune system of the plant. In this way infection remains unnoticed.