​Evolution of immunity and pathogens.- A host-pathogen interaction reduced to first principles: Antigenic variation in T. brucei.- Antigenic variation in Plasmodium falciparum.- Polymorphic mucin-like proteins in Schistosoma mansoni, a variable antigen and a key component of the compatibility between the schistosome and its snail host.- Fibrinogen-related proteins (FREP) in mollusks.- Somatic and germline diversification of a putative immunoreceptor within one phylum: Dscam in arthropods.- An immune effector system in the Protochordate gut sheds light on fundamental aspects of vertebrate immunity.- Variable lymphocyte receptors: a current view.- Antibody repertoire in fish.- Unique features of fish immune repertoires: particularities of the adaptive immunity within the largest group of vertebrates.- The evolution and structure of atypical T cell receptors.- Diversification of the primary antibody repertoire by AID-mediated gene conversion.- Antibody isotype switching in vertebrates.