In a rapid and precise self-defense reaction, larvae of many Drosophila species encapsulate parasitoid wasps’ eggs to inhibit wasp development. Parasitoid wasps of the genus Leptopilina are known to produce extracellular vesicle (EV)-like secretions in their venom. Well-characterized in L. heterotoma, these vesicles kill host hemocytes, respectively, such that the encapsulation response in D. melanogaster is suppressed. A putative virulence protein, SSp40 in L. heterotoma EVs, triggers lamellocyte lysis. SSp40 is structurally similar to the bacterial IpaD and SipD proteins. The immune-suppressive mechanisms of closely related heterotoma clade wasps, L. victoriae, L. pacifica, and L. guineaensis, are not understood. We show that these closely related wasps exhibit markedly distinct abilities to suppress encapsulation in wild-type D. melanogaster hosts. Wasps from the Ganaspis genus, G. brasiliensis and G. hookeri, also elicit differential encapsulation responses in wild-type hosts. Larvae expressing the secreted SSp40 protein showed reduced immune competence, and there was a dose-dependent decrease in their encapsulation capacity. This decrease likely resulted from significant clustering and damage to host hemocytes associated with SSp40 expression. Conversely, infection by SSp40 “knockdown” L. heterotoma wasps, obtained using a novel “hairpin feeding” approach, compromised wasp virulence and induced significantly higher encapsulation in wild-type D. melanogaster hosts. These results establish that SSp40 is a bona fide virulence protein and can damage hemocytes in the absence of other venom proteins. Similar cross-clade studies in this natural host-parasitoid system will help discover other key virulence proteins, identify their activities, and redefine the evolutionary relationships among parasitoid wasps.
","abstract_html":"<p>In a rapid and precise self-defense reaction, larvae of many <em>Drosophila</em> species encapsulate parasitoid wasps’ eggs to inhibit wasp development. Parasitoid wasps of the genus <em>Leptopilina</em> are known to produce extracellular vesicle (EV)-like secretions in their venom. Well-characterized in <em>L. heterotoma</em>, these vesicles kill host hemocytes, respectively, such that the encapsulation response in <em>D. melanogaster</em> is suppressed. A putative virulence protein, SSp40 in <em>L. heterotoma</em> EVs, triggers lamellocyte lysis. SSp40 is structurally similar to the bacterial IpaD and SipD proteins. The immune-suppressive mechanisms of closely related heterotoma clade wasps, <em>L. victoriae</em>, <em>L. pacifica</em>, and <em>L. guineaensis</em>, are not understood. We show that these closely related wasps exhibit markedly distinct abilities to suppress encapsulation in wild-type <em>D. melanogaster hosts</em>. Wasps from the <em>Ganaspis</em> genus, <em>G. brasiliensis</em> and <em>G. hookeri</em>, also elicit differential encapsulation responses in wild-type hosts. Larvae expressing the secreted SSp40 protein showed reduced immune competence, and there was a dose-dependent decrease in their encapsulation capacity. This decrease likely resulted from significant clustering and damage to host hemocytes associated with SSp40 expression. Conversely, infection by SSp40 “knockdown” <em>L. heterotoma</em> wasps, obtained using a novel “hairpin feeding” approach, compromised wasp virulence and induced significantly higher encapsulation in wild-type <em>D. melanogaster</em> hosts. These results establish that SSp40 is a bona fide virulence protein and can damage hemocytes in the absence of other venom proteins. Similar cross-clade studies in this natural host-parasitoid system will help discover other key virulence proteins, identify their activities, and redefine the evolutionary relationships among parasitoid wasps.</p>","abstract_has_math":false,"creators":["Ramsarran, Christina"],"institution":null,"degree_name":"Master of Science (M.S.)","degree_level":"Thesis","degree_discipline":"Biology","degree_department":null,"school":null,"contributors":["Shubha Govind","Yevgeniy Grigoriev","Rebecca Spokony"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2024,"date_issued":"2024-01-01T08:00:00Z","date_published":"2024-01-01T08:00:00Z","updated_at":"2026-07-24T01:58:07Z","subjects":["innate immunity","RNA interference","host-parasite","immune suppression","blood cells","virulence","Genetics"],"languages":[],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://academicworks.cuny.edu/cc_etds_theses/1172","outbound_label":"Repository record","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Shubha Govind","Yevgeniy Grigoriev","Rebecca Spokony"]},{"key":"dc:creator","label":"Author","values":["Ramsarran, Christina"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.available","label":"Dc Date Available","values":["2029-05-30T07:00:00Z"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Biology"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Thesis"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Master of Science (M.S.)"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["innate immunity","RNA interference","host-parasite","immune suppression","blood cells","virulence","Genetics"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://academicworks.cuny.edu/cc_etds_theses/1172"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["In a rapid and precise self-defense reaction, larvae of many Drosophila species encapsulate parasitoid wasps’ eggs to inhibit wasp development. Parasitoid wasps of the genus Leptopilina are known to produce extracellular vesicle (EV)-like secretions in their venom. Well-characterized in L. heterotoma, these vesicles kill host hemocytes, respectively, such that the encapsulation response in D. melanogaster is suppressed. A putative virulence protein, SSp40 in L. heterotoma EVs, triggers lamellocyte lysis. SSp40 is structurally similar to the bacterial IpaD and SipD proteins. The immune-suppressive mechanisms of closely related heterotoma clade wasps, L. victoriae, L. pacifica, and L. guineaensis, are not understood. We show that these closely related wasps exhibit markedly distinct abilities to suppress encapsulation in wild-type D. melanogaster hosts. Wasps from the Ganaspis genus, G. brasiliensis and G. hookeri, also elicit differential encapsulation responses in wild-type hosts. Larvae expressing the secreted SSp40 protein showed reduced immune competence, and there was a dose-dependent decrease in their encapsulation capacity. This decrease likely resulted from significant clustering and damage to host hemocytes associated with SSp40 expression. Conversely, infection by SSp40 “knockdown” L. heterotoma wasps, obtained using a novel “hairpin feeding” approach, compromised wasp virulence and induced significantly higher encapsulation in wild-type D. melanogaster hosts. These results establish that SSp40 is a bona fide virulence protein and can damage hemocytes in the absence of other venom proteins. Similar cross-clade studies in this natural host-parasitoid system will help discover other key virulence proteins, identify their activities, and redefine the evolutionary relationships among parasitoid wasps.
"]},{"key":"dc:title","label":"Title","values":["Understanding Virulence Mechanisms of Parasitoid Wasps of Drosophila: A Comparative Approach Across Clades"]}]}],"canonical_facts":{"dc:contributor":["Shubha Govind","Yevgeniy Grigoriev","Rebecca Spokony"],"dc:creator":["Ramsarran, Christina"],"dc:date.available":["2029-05-30T07:00:00Z"],"dc:description.abstract":["In a rapid and precise self-defense reaction, larvae of many Drosophila species encapsulate parasitoid wasps’ eggs to inhibit wasp development. Parasitoid wasps of the genus Leptopilina are known to produce extracellular vesicle (EV)-like secretions in their venom. Well-characterized in L. heterotoma, these vesicles kill host hemocytes, respectively, such that the encapsulation response in D. melanogaster is suppressed. A putative virulence protein, SSp40 in L. heterotoma EVs, triggers lamellocyte lysis. SSp40 is structurally similar to the bacterial IpaD and SipD proteins. The immune-suppressive mechanisms of closely related heterotoma clade wasps, L. victoriae, L. pacifica, and L. guineaensis, are not understood. We show that these closely related wasps exhibit markedly distinct abilities to suppress encapsulation in wild-type D. melanogaster hosts. Wasps from the Ganaspis genus, G. brasiliensis and G. hookeri, also elicit differential encapsulation responses in wild-type hosts. Larvae expressing the secreted SSp40 protein showed reduced immune competence, and there was a dose-dependent decrease in their encapsulation capacity. This decrease likely resulted from significant clustering and damage to host hemocytes associated with SSp40 expression. Conversely, infection by SSp40 “knockdown” L. heterotoma wasps, obtained using a novel “hairpin feeding” approach, compromised wasp virulence and induced significantly higher encapsulation in wild-type D. melanogaster hosts. These results establish that SSp40 is a bona fide virulence protein and can damage hemocytes in the absence of other venom proteins. Similar cross-clade studies in this natural host-parasitoid system will help discover other key virulence proteins, identify their activities, and redefine the evolutionary relationships among parasitoid wasps.
"],"dc:identifier":["https://academicworks.cuny.edu/cc_etds_theses/1172"],"dc:subject":["innate immunity","RNA interference","host-parasite","immune suppression","blood cells","virulence","Genetics"],"dc:title":["Understanding Virulence Mechanisms of Parasitoid Wasps of Drosophila: A Comparative Approach Across Clades"],"thesis:degree_discipline":["Biology"],"thesis:degree_level":["Thesis"],"thesis:degree_name":["Master of Science (M.S.)"]},"updated_at":"2026-07-24T01:58:07Z"}