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Updated: Aug 14, 2026
Evaluation of T Follicular Helper Cells and Germinal Center Response During Influenza A Virus Infection in Mice
Published on: June 27, 2020
Bone marrow immunosuppression in Salmonella-infected mice is prolonged following influenza virus infection
Lisa Hyland1, Bernardo Villarreal-Ramos, Ben Clarke
1The Edward Jenner Institute for Vaccine Research, Compton, Newbury, Berkshire, UK. lisa.hyland@jenner.ac.uk
Objective:
It has been shown previously that infection with diverse viruses induces alterations in bone marrow lineage-specific progenitor cells. As complications arising from secondary bacterial infections can adversely affect the host, we investigated whether virally induced hematological alterations could contribute to the enhanced illness observed in such cases.
Materials And Methods:
Mice were infected with influenza virus alone or influenza virus followed by a vaccine strain of Salmonella typhimurium. The effects on hematopoiesis were analyzed by fluorescein-activated cell sorting analysis and immunohistology.
Results:
Systemic Salmonella typhimurium infection induces depletion of bone marrow erythroid and lymphoid cells. The depletion lasted longer in mice that had been previously infected with influenza virus, compared with mice that had been previously treated with allantoic fluid. Although an increase in splenic lymphoid cells was apparent in the spleens of Salmonella-infected mice, the majority of cells in the enlarged spleens were found to be both immature and mature erythrocytes.
Conclusion:
These results show that bone marrow progenitor cell depletion induced by bacterial infection is prolonged following a viral infection. It is possible that hematological alterations may contribute to the enhanced clinical illness observed in consecutive viral:bacterial infections.
Insights
Viral infections prolong bone marrow cell depletion caused by bacterial infections. This prolonged depletion of hematopoietic stem cells may worsen illness during secondary bacterial infections following viral infections.
Area of Science:
- Immunology
- Hematology
- Virology
Background:
- Viral infections are known to alter bone marrow progenitor cells.
- Secondary bacterial infections can worsen illness in hosts.
Purpose of the Study:
- To investigate if virally induced hematological alterations contribute to enhanced illness in consecutive viral-bacterial infections.
- To analyze the impact of influenza virus infection on subsequent Salmonella typhimurium infection outcomes.
Main Methods:
- Mice were infected with influenza virus, followed by Salmonella typhimurium.
- Hematopoiesis was analyzed using fluorescein-activated cell sorting and immunohistology.
Main Results:
- Salmonella typhimurium infection depleted bone marrow erythroid and lymphoid cells.
- Previous influenza virus infection prolonged this depletion.
- Enlarged spleens in Salmonella-infected mice contained immature and mature erythrocytes.
Conclusions:
- Bacterial infection-induced bone marrow progenitor cell depletion is prolonged after viral infection.
- Hematological alterations may contribute to increased severity in sequential viral-bacterial infections.
