Biogenesis, structure, and immune-suppressive effects of virus-like particles of a Drosophila parasitoid, Leptopilina victoriae

Previously undocumented precursors of L. victoriae VLPs are synthesized in the long gland and are first visible within canals connecting secretory cells to the long gland lumen. VLP assembly occurs in the lumen. VLPs show multiple electron-dense projections surrounding a central core. Maturing particles appear segmented, singly or in arrays, embedded in the reservoir matrix. In sections, mature particles are pentagonal or hexagonal; the polygon vertices extending into spikes. Our results suggest that L. victoriae is likely to promote immune suppression by an active mechanism that is mediated by VLPs, similar to that used by L. heterotoma.