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Effect of dengue virus infection on Fc-receptor functions of mouse macrophages
Abstract:
Fc-receptor-mediated attachment and ingestion of opsonized sheep erythrocytes (EA) by the macrophages of spleen and peritoneal cavity were studied during dengue virus type 2 (DV) infection of Swiss albino mice. Following intracerebral inoculation, virus antigen could be demonstrated by immunofluorescence in the splenic macrophages from day 4 and in peritoneal macrophages from day 5 post-infection, with a higher number of positive cells discernible on the 7th and 8th days. The virus could be isolated from spleen tissue from day 5. The total number of cells was markedly reduced from day 4 onwards both in the spleen and peritoneal cavity. A loss in the capacity to attach and ingest EA was noticed, the lowest values of attachment index (AI) and phagocytic index (PI) being reached on day 4. At later periods the AI values increased markedly but continued to be significantly less than those in uninfected control mice. The PI values continued to be lower throughout. The dichotomy between the Fc-mediated attachment and ingestion may be a mechanism for prevention of virus infection of macrophages.
Insights
Dengue virus type 2 infection impairs macrophage function in mice, reducing their ability to engulf pathogens. This dysfunction may protect macrophages from further viral infection.
Area of Science:
- Immunology
- Virology
- Cell Biology
Background:
- Dengue virus type 2 (DV) infection impacts immune cells.
- Macrophages play a crucial role in innate immunity and pathogen clearance.
Purpose of the Study:
- To investigate the effect of DV infection on Fc-receptor-mediated functions of splenic and peritoneal macrophages in mice.
- To understand the potential mechanisms of macrophage protection during viral infection.
Main Methods:
- Swiss albino mice were intracerebrally inoculated with DV type 2.
- Virus antigen presence was detected using immunofluorescence.
- Virus isolation from spleen tissue was performed.
- Macrophage attachment and ingestion of opsonized sheep erythrocytes (EA) were assessed using attachment index (AI) and phagocytic index (PI).
Main Results:
- Virus antigen was detected in splenic and peritoneal macrophages post-infection.
- Significant reduction in splenic and peritoneal cell counts observed from day 4.
- Impaired capacity of macrophages to attach and ingest EA, with lowest AI and PI on day 4.
- AI values partially recovered but remained lower than controls; PI values remained consistently low.
Conclusions:
- DV infection significantly impairs Fc-receptor-mediated phagocytosis by macrophages.
- A potential dichotomy between attachment and ingestion mechanisms may serve as a protective strategy for macrophages against DV infection.