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Immune suppressive virus-like particles in a Drosophila parasitoid: significance of their intraspecific morphological variations

Published online by Cambridge University Press:  06 April 2009

S. Dupas ,
M. Brehelin ,
F. Frey  and
Y. Carton
S. Dupas*
Affiliation:
Laboratoire Populations, Genetique et Evolution, CNRS 91198 Gif-sur-Yvette CEDEX, France
M. Brehelin
Affiliation:
INRA-CNRS URA 1184, Pl E. Bataillon, 34095 Montpellier, France
F. Frey
Affiliation:
Laboratoire Populations, Genetique et Evolution, CNRS 91198 Gif-sur-Yvette CEDEX, France
Y. Carton
Affiliation:
Laboratoire Populations, Genetique et Evolution, CNRS 91198 Gif-sur-Yvette CEDEX, France
*
* Corresponding author. Tel: 69823714. Fax: 69824448. E-mail: [email protected].
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Summary

The Eucoilid parasitoid Leptopilina boulardi is able to suppress its host Drosophila melanogaster immune reaction. Some strains, however, are non-immune suppressive to that host. Virus-like particles (VLPs) responsible for the immune suppressive ability were investigated in different strains of L, boulardi with histochemical and ultrastructural techniques. Membrane-bound particles containing vesicles were observed in the reservoir of the long gland and also in the egg canal of the ovipositor. These particles are homologous with the immune suppressive VLPs already described in the reservoir of L. heterotoma. Similarities were also observed with the L2 particles described previously around the chorion of the parasitoid egg after infestation. A weak positive DNA specific histochemical reaction was observed inside the reservoir and at the ultrastructural level. Feulgen-derived techniques demonstrated that the reaction was localized inside the particles. The morphology of the particles as well as the immune suppressive ability varied between strains. Two morphotypes of VLPs are described; the ‘Is’ morphotype (always observed in immune suppressive or Is strains) and the ‘NIs’ morphotype (observed in the non-immune suppressive or NIs strain). The hybrids between Is and NIs strains produce a third type of particle, the ‘His’morphotype with half-immune suppressive ability and intermediate morphology. The origin of the particles' immune suppressive activity against D. melanogaster is discussed within the scope of host specificity.

Keywords

Leptopilina boulardivirus-like particlesimmune suppressive abilityintraspecific variability
Type
Research Article
Information
Parasitology , Volume 113 , Issue 3 , September 1996 , pp. 207 - 212
Copyright
Copyright © Cambridge University Press 1996

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