ABSTRACT
This review will discuss the many types of antimicrobial molecules that were conserved across phyla as an innate mechanism of defense/resistance against microorganisms. Innate immune mechanisms of vertebrates and invertebrates include a variety of antimicrobial molecules that show a remarkable degree of structural and functional conservation across species representing diverse taxa. Structurally and in their mode of action, these molecules vary considerably and include proteins (e.g., lysozyme, alpha-2-macroglobulin [α2M], chitinase, granulysin), peptides (e.g., defensins), bioactive fragments of larger proteins (e.g., histone fragments and cathelicidins), enzyme systems (such as those responsible for intracellular oxidative killing of microorganisms), and nonprotein antimicrobials such as squalamine. These molecules vary in their antimicrobial activity from those that use enzymatic digestion to lyse bacterial cell walls to molecules that kill by using 268nonenzymatic chelation. Herein the antimicrobial molecules that were reported in elasmobranch species are described and a comparison with similar molecules found in other taxa is provided.
