Submitted to: Society for Invertebrate Pathology Annual Meeting Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 7/15/2000
Publication Date: N/A
Interpretive Summary: NA
Technical Abstract: Most Nucleopolyhedroviruses (NPVs) and Granuloviruses (GVs) have an initial colonization phase of replication in the nuclei of midgut epithelial cells where budded virions (BV) are produced that spread the virus to other tissues in the body. The mechanisms for the spread of baculoviruses that are found only in midgut tissues are not known. Insect baculoviruses restricted to the midgut epithelium are NPVs from Hymenoptera, Thysanura, Trichoptera, and Diptera and one species of GV (HbGV) from Harrisina brillians. A new Dipteran baculovirus isolated from the larval stages of the mosquito Culex nigripalpus specifically infects and develops occlusion bodies in midgut epithelial cells. We have studied the early phases of virogenesis and found evidence that lateral spread of this mosquito baculovirus within the midgut occurred by means of BV. Non-enveloped nucleocapsids were released from infected nuclei into the cytoplasm of midgut epithelial cells by budding through the nuclear envelope. These nucleocapsids exited the nucleus either singly or in groups forming transport vesicles in the process. The membranes of these transport vesicles (formed by the membranes of the nuclear envelope) break down and release the naked nucleocapsids into the cytoplasm. This process is similar to the lateral transmission mechanisms established for NPVs and GVs that spread from the midgut to other tissues and may help resolve these mechanisms for baculoviruses restricted to the nuclei of midgut epithelium.