 These pathogens include HIV-1, helminthic parasites such as schistosomes, and Helicobacter pylori, the bacterium that causes stomach ulcers.There are some notable examples of this mimicry or acquisition of the same carbohydrate sequences implicated in this protective system by pathogens and aggressive tumor cells.The major carbohydrate sequence linked to glycodelin-A also profusely coats the surface of schistosomes.