[Spd1672 gene knockout significantly attenuates the virulence of Streptococcus pneumoniae]
Jian Huang1, MeiRong Huang, Kaifeng Wu
1Department of Clinical Laboratory, 2Department of Blood Transfusion, Affiliated Hospital of Zunyi Medical College, Zunyi 563003, China.
Objective:
To investigate the role of spd1672 gene in the infection process of Streptococcus pneumoniae.
Methods:
BALB/c mice were intraperitoneally infected by a spd1672 knockout strain and a D39 wild-type strain of S. pneumoniae, and the survival time of mice and blood bacterial counts were recorded. The adhesion and invasion ability of S. pneumoniae strains were assessed in A549 cells. Bactericidal assays were carried out to determine the resistance of spd1672 knockout strains and D39 wild strains, and the serum levels of inflammatory cytokines were detected in the infected mice.
Results:
The mice infected with spd1672 knockout strains showed a significantly longer median survival time, a higher survival rate, and a lower blood bacterial load than the wild strain-infected mice (P<0.05). Having a similar cell adhesion ability to the wild-type strain (P>0.05), the spd1672 knockout strain showed significantly lower cell invasion ability than the wild-type strain (P<0.05). The spd1672 knockout strain also had a reduced resistance to whole blood cells, and thw mice infected with spd1672 knockout strain exhibit lower levels of serum inflammatory cytokines than those infected with the wild-type strain.
Conclusion:
Spd1672 gene is importantly related to the virulence of S. pneumoniae and plays important roles in modulating bacterial invasion, resistance to whole blood cells and proinflammatory responses.
Insights
The spd1672 gene is crucial for Streptococcus pneumoniae virulence, impacting bacterial invasion and immune evasion. Deleting this gene in S. pneumoniae enhances host survival and reduces inflammation.
Area of Science:
- Microbiology
- Infectious Diseases
- Genetics
Background:
- Streptococcus pneumoniae is a major cause of bacterial infections worldwide.
- Understanding bacterial virulence factors is key to developing new treatments.
Purpose of the Study:
- To investigate the function of the spd1672 gene in Streptococcus pneumoniae pathogenesis.
- To determine the role of spd1672 in bacterial invasion, immune resistance, and host inflammatory responses.
Main Methods:
- Comparison of a spd1672 knockout strain with a wild-type strain in a murine infection model.
- Assessment of bacterial adhesion and invasion in A549 cell cultures.
- Evaluation of bacterial resistance to whole blood lysis and host cytokine profiles.
Main Results:
- Mice infected with the spd1672 knockout strain exhibited significantly increased survival rates and reduced bacterial loads.
- The knockout strain showed similar adhesion but significantly lower invasion capabilities compared to the wild-type.
- spd1672 knockout strains demonstrated reduced resistance to whole blood and elicited lower serum inflammatory cytokine levels in infected mice.
Conclusions:
- The spd1672 gene is a significant virulence factor for Streptococcus pneumoniae.
- spd1672 modulates bacterial invasion, resistance to host immune defenses, and the host's inflammatory response.
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