Venom Proteins from Endoparasitoid Wasps and Their Role in Host-Parasite Interactions

Abstract

Endoparasitoids introduce a variety of factors into their host during oviposition to ensure successful parasitism. These include ovarian and venom fluids that may be accompanied by viruses and virus-like particles. An overwhelming number of venom components are enzymes with similarities to insect metabolic enzymes, suggesting their recruitment for expression in venom glands with modified functions. Other components include protease inhibitors, paralytic factors, and constituents that facilitate/enhance entry and expression of genes from symbiotic viruses or virus-like particles. In addition, the venom gland may itself support replication/production of some viruses or virus-like entities. Overlapping functions and structural similarities of some venom, ovarian, and virus-encoded proteins suggest coevolution of molecules recruited by endoparasitoids to maintain their fitness relative to their host.

Extracellular Superoxide Dismutase in Insects

“…Until now, a limited number of proteins have been identified and characterized from parasitoid venom fluids, and only a few of them have been demonstrated to interfere with host immune defenses (10). Known immune-suppressive proteins target either host hemocytes or the PO cascade (10), as shown for Leptopilina boulardi, a parasitoid of Drosophila species of the melanogaster subgroup (2).…”

“…Known immune-suppressive proteins target either host hemocytes or the PO cascade (10), as shown for Leptopilina boulardi, a parasitoid of Drosophila species of the melanogaster subgroup (2). This species is likely the best known parasitoid model regarding venom virulence factors, and it is also an important model for understanding intraspecific varia-tion of virulence with the occurrence of two well characterized strains, ISm and ISy (for review, see Ref.…”

Functional analysis of the venom of mealybug parasitoid Aenasius bambawalei (Hymenoptera: Encyrtidae)

“…These components include calyx fluid, venom proteins and symbiotic viruses and virus-like particles (VLPs) such as polydnaviruses (PDVs) etc. (Asgari & Rivers 2011) which are injected by the ovipositing female wasp to suppress the host immune response (Pennacchio & Strand 2006).…”

“…The venom of parasitic hymenoptera has the potential for developing novel environmentally safe insect control strategies and it is a blend of biologically, pharmacologically and physiologically complex mixture of peptides, biogenic amines, proteinaceous and nonproteinaceous compounds. Physiological and molecular studies exploring the functional role of the parasitic venom in host regulation processes have been carried out for the last few decades (Asgari & Rivers 2011). Female wasp injects venom into their hosts during the parasitization process in order to regulate the host's immunity and physiology for the interest of the development of its offspring.…”

Sex differences in the protection of host immune systems by a polyembryonic parasitoid

“…The most important challenge for parasitoids is to circumvent the host cellular immune response, which will lead to haemocytic encapsulation [2,3]. Many parasitoids are known to suppress host immunity [4]; for example, some parasitoids in the Braconidae and Ichneumonidae suppress it by maternal secretions of polydnaviruses, venom and ovarian proteins [2,5,6]. However, such suppression is likely to enhance the host's susceptibility to fungal, bacterial and viral infections [7], resulting in an immunological dilemma for the parasitoids.…”