ULTRASTRUCTURAL-CHANGES IN THE MILK GLAND OF TSETSE GLOSSINA-MORSITANS-CENTRALIS (DIPTERA, GLISSINIDAE) FEMALE INFECTED BY A DNA VIRUS

Milk glands, dissected out and collected from Glossina morsitans centr alis (Machado) females, artificially inoculated at the third-instar la rval stage with a virus suspension obtained from hypertrophied salivar y glands of wild-caught virus-infected Glossina pallidipes (Austen), w ere processed for routine electron microscopy and examined for patholo gical changes. They were compared to milk glands dissected out from no rmal female G.m. centralis at the same stage of pregnancy cycle. Upon dissection there were notable physical differences between control and virus-infected milk glands. Histologically, some areas of the gland d eveloped severe degeneration while other areas developed less severe p athological changes. Ultrastructural studies revealed the presence of virus particles in the secretory cell nuclei and within the cytoplasm and also showed that the nucleus was the site of virogenesis with matu re naked virions budding through the nuclear membrane and acquiring th e envelope from the nuclear membrane. Milk glands from normal females showed normal cellular organization of the secretory cells and secreto ry vesicles around the collecting gland lumen. The demonstration of vi rus particles in the secretory cell nuclei and cytoplasm suggests anot her mode of transmission of the virus from the infected mother to the larva in utero. (C) 1996 Academic Press, Inc.