| dc.description.abstract | Cartilaginous fish are located at a pivotal point in phylogeny where the adaptive immune system begins to resemble that of other, more-derived jawed vertebrates, including mammals. For this reason, sharks and other cartilaginous fish are ideal models for studying the natural history of immunity. The cartilaginous skeleton of sharks lacks bone marrow, also absent in bony fish despite calcified bone, but cartilaginous fish have other organs that function to provide hematopoiesis. Conserved across all vertebrate phylogeny in some form is gut-associated lymphoid tissues (GALT) which is seen from agnathans to mammals. Though it takes many forms, from typhlosole in lamprey to Peyer’s patches in mammals. Though more complex lymphoid organs are not present in agnathans, they have several primitive tissues that appear to serve their variable lymphocyte receptor-based adaptive immune system. There are several similarities between the adaptive immune structures in cartilaginous and bony fish, such as the thymus and spleen, but there are mechanisms employed in bony fish that in some instances bridge their adaptive immune systems to that of tetrapods. Cattle has a restricted repository of antibody gene segments usable for antibody formation. Among these segments are a V and D that, together, form an antibody with an ultralong CDR3 region that manifests as a “knob” and “stalk” domain of which the knob has antigen binding capability. This antibody has boundless therapeutic potential, including for treatment of HIV and other antigens with veiled epitopes. The ultralong antibody appears in more species than just Bos taurus; it expands throughout the bovine subfamily as evidence by the presence of a V motif “TTVHQ”, an 8 base-pair (bp) duplication, and a, comparatively, long D segment. The evolutionary event which led to the appearance of the ultralong antibody can only be speculated at this time. What we know for sure is that the cattle ultralong antibody is an invaluable tool in the bovine immunity toolbox. | |
