Pilosulins: A review of the structure and mode of action of venom peptides from an Australian ant Myrmecia pilosula

Myrmecia pilosula is an endemic Australian ant whose sting is a frequent cause of insect allergy in southeast Australia, and several deaths due to M. pilosula sting envenomation have been documented. In this review, we discuss the composition and bioactivity of M. pilosula venom. In addition to various enzymes and pharmacologically active constituents, the venom contains four families of highly basic low molecular weight peptides trivially named Pilosulins. These peptides are unique and have low structural homology to other Hymenoptera venom peptides. Moreover, M. pilosula venom is relatively simple in its composition with 5 predominant peptides making up about 90% by weight. These peptides display cytotoxic, hypotensive, histamine-releasing and antimicrobial activities. Within the M. pilosula venom, Pilosulin 3 has been classified as a major allergen and [Ile5]pilosulin 1 and Pilosulin 4.1 are classified as minor allergens. Several uncharacterised higher molecular weight components with allergenic activities have also been identified. The revised naming of M. pilosula venom peptides according to the International Union of Immunological Societies (IUIS) criteria for allergen nomenclature is discussed in this review.