Cell Death in the Host-Parasitoid Relationship (original) (raw)

New developments in cell apoptosis research, 2007

Abstract

ABSTRACT Cell death, specifically apoptosis, is a feature of host-parasitoid relationships involving parasitic wasps. Though there are numerous examples of endosymbiotic virus-induced (e.g., polydnaviruses) and venom-mediated apoptosis in host hemocytes, there is very little evidence for this form of cell death being triggered in other host tissues. Is this due to specificity in tissue responsiveness? In terms of timing of events during parasitism (i.e., at the initial stages of parasitism), this is a likely scenario. But throughout the duration of the association between the parasitoid and host, several developmental and physiological changes in host tissues may be regulated by apoptotic signals. There simply is very little evidence to draw any conclusions. Somewhat surprisingly, in most instances when apoptosis has been identified in host tissue (hemocytes), investigations of the pathways involved or specific intracellular changes have apparently not been conducted. Consequently, apoptosis is known to be induced by polydnaviruses, but what relationships exist between this form of cell death and those triggered by wasp venoms are unclear, nor have any attempts been made to compare mechanisms of oncosis evoked by these viruses and parasitoid venoms. What follows is an attempt to show homology in the modes of death evoked by pathogenic insect viruses, endosymbiotic viruses that reside within endoparasitic wasps, and venoms produced by ectoparasitic wasps. As will be discussed, oncosis and apoptosis are intimately linked by common signal transduction pathways and mitochondria. The focus of this paper is to attempt to provide evidence, admittedly at times circumstantial, and speculation on the possible linkage between the modes of action of ectoparasitic wasp venoms and insect viruses.

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