Cytopathological process by multiple nucleopolyhedrovirus in the testis of Bombyx mori L., 1758 (Lepidoptera:
Eliana Peliçon Pereira1, Hélio Conte, Lucinéia de Fátima Chasko Ribeiro
1Departamento de Biologia Celular e Genética, Laboratório de Morfologia e Citogenética de Insetos, Universidade Estadual de Maringá, PR, Brazil.
Abstract:
A cytopathological methodology was used to analyze infection by Bombyx mori multiple nucleopolyhedrovirus (BmMNPV), a geographic isolate of the family Baculoviridae, in the caterpillar testes of the B. mori. Japanese B. mori strain caterpillar, fifth instar, were inoculated with BmMNPV and their testes were collected and processed for light and transmission electronic microscopy. Epithelial coating cells and interfollicular septa in testes were susceptible to BmMNPV. The first evidence of infection was detected on the 6th day post-inoculation (p.i.) in the external epithelium, and on the 7th day p.i. in the internal epithelium and interfollicular septa. Cytopathological characteristics consisted of hypertrophied nuclei, the formation of virogenic stroma, and the occlusion of virions in polyhedron protein crystals in several stages of development. At the end of the infectious process, cell lysis and release of polyhedra into the extracellular medium occurred. Histopathology revealed early infection foci in the surrounding regions of tracheal insertions, thus underlining the role of the trachea as an infection-spreading organ in insects. This spreading occurs through penetration of the basal lamina, which facilitates entry of the budded virus into the testis. Additionally, an alignment of a partial sequence of the ORF 14 of the BmMNPV geographic isolate with other NPV certified the virus genera.
Insights
Bombyx mori multiple nucleopolyhedrovirus (BmMNPV) infects silkworm testes, causing hypertrophied nuclei and virion occlusion. Trachea facilitate virus spread, highlighting BmMNPV
Area of Science:
- Insect Pathology
- Virology
- Cell Biology
Background:
- Baculoviridae, specifically Bombyx mori multiple nucleopolyhedrovirus (BmMNPV), are significant pathogens of Lepidoptera.
- Understanding BmMNPV infection dynamics in silkworm (B. mori) is crucial for disease management in sericulture.
Purpose of the Study:
- To characterize the cytopathological effects of BmMNPV infection in silkworm testes.
- To investigate the route of BmMNPV dissemination within the silkworm testes and identify early infection sites.
Main Methods:
- Cytopathological analysis using light and transmission electron microscopy.
- Histopathological examination of infected silkworm testes.
- Partial sequencing of the BmMNPV ORF 14 for viral genus confirmation.
Main Results:
- BmMNPV infection was observed in epithelial coating cells and interfollicular septa of B. mori testes.
- Cytopathological hallmarks included hypertrophied nuclei, virogenic stroma formation, and virion occlusion within polyhedron protein crystals.
- Tracheal insertions were identified as early infection foci, with virus spread facilitated by basal lamina penetration.
Conclusions:
- BmMNPV infects specific cell types within silkworm testes, leading to characteristic cytopathological changes.
- The insect trachea plays a vital role in the systemic spread of BmMNPV.
- Sequence analysis confirmed the BmMNPV isolate belongs to the NPV genus.
