Polydnavirus hidden face: the genes producing virus particles of parasitic wasps.

Very few obligatory relationships involve viruses to the remarkable exception of polydnaviruses (PDVs) associated with tens of thousands species of parasitic wasps that develop within the body of lepidopteran larvae. PDV particles, injected along with parasite eggs into the host body, act by manipulating host immune defences, development and physiology, thereby enabling wasp larvae to survive in a potentially harmful environment. Particle production does not occur in infected tissues of parasitized caterpillars, but is restricted to specialized cells of the wasp ovaries.

Polydnaviruses of braconid wasps derive from an ancestral nudivirus.

Many species of parasitoid wasps inject polydnavirus particles in order to manipulate host defenses and development. Because the DNA packaged in these particles encodes almost no viral structural proteins, their relation to viruses has been debated. Characterization of complementary DNAs derived from braconid wasp ovaries identified genes encoding subunits of a viral RNA polymerase and structural components of polydnavirus particles related most closely to those of nudiviruses--a sister group of baculoviruses.

Wolbachia mediate variation of host immunocompetence.

Background: After decades during which endosymbionts were considered as silent in their hosts, in particular concerning the immune system, recent studies have revealed the contrary. In the present paper, we addressed the effect of Wolbachia, the most prevalent endosymbiont in arthropods, on host immunocompetence. To this end, we chose the A.

Bracovirus gene products are highly divergent from insect proteins.

Recently, several polydnavirus (PDV) genomes have been completely sequenced. The dsDNA circles enclosed in virus particles and injected by wasps into caterpillars appear to mainly encode virulence factors potentially involved in altering host immunity and/or development, thereby allowing the survival of the parasitoid larvae within the host tissues. Parasitoid wasps generally inject virulence factors produced in the venom gland.

Protein profiling of hemocytes from the terrestrial crustacean Armadillidium vulgare.

To establish and maintain a successful infection, microbial pathogens have evolved various strategies to infect the host in the face of a functional immune system. In this context, the alpha-proteobacteria Wolbachia capacities to infect new host species have been greatly evidenced. Indeed, in terrestrial isopods, experimentally transferred Wolbachia invade all host tissues, including immune cells such as hemocytes.

Armadillidin: a novel glycine-rich antibacterial peptide directed against gram-positive bacteria in the woodlouse Armadillidium vulgare (Terrestrial Isopod, Crustacean).

We report the isolation and the characterization of a novel antibacterial peptide from hemocytes of the woodlouse Armadillidium vulgare, naturally infected or uninfected by Wolbachia, an intracellular Gram-negative bacterium. This molecule displays antibacterial activity against Gram-positive bacteria despite its composition which classes it into the glycine-rich antibacterial peptide family, usually directed against fungi and Gram-negative bacteria. The complete sequence was determined by a combination of Edman degradation, mass spectrometry and cDNA cloning using a hemocyte library.