Polydnavirus replication and tissue organization of infected cells in the parasitic wasp Diadegma terebrans

Female parasitic wasps of the species Diadegma terebrans produce a polydnavirus, DtPV, in cells of the calyx. The virus morphology is similar to that of other polydnaviruses. It has a segmented superhelical DNA genome with an estimated size range of 2.3 to 5.5 kilobases. DtPV replication starts within large nuclei where nucleocapsids assemble and become enveloped. They bud through the nuclear envelope and are then "secreted" through the apical microvilli into either the calyx lumen directly or into a channel which is continuous with the lumen. DtPV-producing cells are distributed throughout the length of the calyx and form a discrete, one cell thick "tissue" within it. The large, sector-shaped, DtPV-producing cells form a semicircle around the calyx lumen near the ovariole end of the calyx. This semicircle of DtPV-infected cells increases in circumference towards the lateral oviduct end of the calyx until they completely encircle the lumen and form the major component of the calyx wall.