A new entomopoxvirus from a cockroach: Light and electron microscopy

The cockroach entomopoxvirus caused a chronic infection in cultures of the German cockroach Blattella germanica. Heavily infected specimens showed a r educed mobility. Ellipsoid virus occlusion bodies (8 x 5 to 19 x 12 mu m) w ere found intracellularly in tracheole cells, in the hypodermis, in fat bod y cells, and in muscles. Several hundred virus particles were integrated in a single occlusion body (OB), their long axis being oriented axially. Ovoi d viroids measured 320 x 190 nm and possessed a unilateral, concave core an d one lateral body. Starting occlusion, small granules attached to the viru s particles which later transformed to a beaded, wavy envelope. An initial halo around the occluded virions disappeared in more central regions of the OB. Virus particles were formed either in a dense cytoplasmic area contain ing electron-dense viroids, or in a loosely aggregated viroplasm. In the la tter, developmental stages were mainly represented by spheres with double m embranes enclosing granular material. Spindles and larger crystal-like viru s-free inclusion bodies occurred in the cytoplasm. The cytoplasm of infecte d cells appeared degenerated and the chromatin of the nuclei condensed at t he periphery or disintegrated. Taxonomically, the described virus exhibits features of both EPV genus A and EPV genus B. Provisory it is named Blattel la germanica EPV (BgEPV). A possible use of the cockroach EPV as a biologic al control agent is discussed. (C) 2000 Academic Press.