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Experimental infection of newborn mice with murine EDIM rotavirus
M A Guimarães1, V Chagas, C Nozawa
1Departamento de Virologia, Universidade Federal do Rio de Janeiro, Brasil.
Abstract:
All four-day old Swiss mice whose dams were seronegative to rotavirus developed diarrhea 72 h after oral infection with EDIM rotavirus (HP strain). Electron microscopy of infected small intestine showed rotavirus particles of different sizes and morphology in the intestinal absorptive cells. In these cells rotavirus particles of 30 to 60 nm representing the various steps of virus maturation were visualized in viroplasm near the rough endoplasmic reticulum (RER). Mature rotavirus particles of 70 nm approximately were observed inside the RER of the intestinal absorptive cells. In the lamina propria rotavirus particles of approximately 30 nm and tubules were observed in phagosome-like structures of subepithelial phagocytes and were probably destroyed by lysosomal enzymes. The absence of signs of viral replication in phagocytes of lamina propria suggests that this may be the mechanism for viral antigen presentation to the host immunological system and may be one of the reasons for the fact that rotavirus infection is limited to the intestine.
Insights
Young Swiss mice infected with EDIM rotavirus developed diarrhea and showed virus particles in intestinal cells. Rotavirus maturation occurred in the endoplasmic reticulum, with particles in the lamina propria likely destroyed by enzymes, limiting infection.
Area of Science:
- Virology
- Gastroenterology
- Immunology
Background:
- Rotavirus is a major cause of severe diarrhea in infants worldwide.
- Understanding rotavirus pathogenesis is crucial for developing effective treatments and vaccines.
Purpose of the Study:
- To investigate the cellular events and viral dynamics during EDIM rotavirus infection in young mice.
- To elucidate the role of intestinal cells and phagocytes in rotavirus replication and host response.
Main Methods:
- Oral infection of four-day-old Swiss mice with EDIM rotavirus (HP strain).
- Electron microscopy of infected small intestine to visualize rotavirus particles and cellular structures.
- Analysis of rotavirus presence and maturation stages within intestinal absorptive cells and subepithelial phagocytes.
Main Results:
- Diarrhea observed 72 hours post-infection in all infected mice.
- Rotavirus particles at various maturation stages (30-60 nm) visualized in viroplasm near the rough endoplasmic reticulum (RER) of absorptive cells.
- Mature rotavirus particles (approx. 70 nm) found within the RER.
- Smaller rotavirus particles (approx. 30 nm) and tubules observed in phagosome-like structures within lamina propria phagocytes, suggesting degradation by lysosomal enzymes.
Conclusions:
- Rotavirus replication is confined to intestinal absorptive cells, with maturation occurring in the RER.
- Phagocytosis and lysosomal degradation of rotavirus in lamina propria phagocytes may limit viral spread.
- This process might be a key mechanism for viral antigen presentation, contributing to the intestinal localization of rotavirus infection.