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Published on: July 28, 2015
Virulence factors of Salmonella Typhi: interplay between the bacteria and host macrophages
Jiayin Guo1, Xiaoe He1, Yanrui Bai1
1Cuiying Biomedical Research Center, The Second Hospital & Clinical Medical School, Lanzhou University, Cuiying Gate 82, Lanzhou, Gansu, 730030, China.
Abstract:
Salmonella Typhi (S. Typhi) is a Gram-negative bacterium that exclusively infects humans and causes typhoid fever- a major global public health concern responsible for approximately 9 million infections and 110,000 deaths annually. Macrophages, a key component of the innate immune system, play essential roles in pathogen clearance, antigen presentation, immune regulation, and tissue repair. As one of the primary targets of S. Typhi infection, macrophages significantly influence disease onset and progression. S. Typhi expresses a range of virulence factors, including the virulence-associated (Vi) capsule, outer membrane proteins (OMPs), flagella, fimbriae, type III secretion systems (T3SSs) and other genes encoded on Salmonella pathogenicity islands (SPIs), as well as toxins, regulatory factors, and virulence plasmids. These virulence factors facilitate S. Typhi's intracellular survival within macrophages by mediating processes such as adhesion, invasion, nutrient acquisition and immune evasion, ultimately enabling systemic infection. This review explores the role and molecular mechanisms of S. Typhi virulence factors in counteracting macrophage antimicrobial functions, providing insights for future research on typhoid pathogenesis and the development of potential therapeutic interventions.
Insights
Salmonella Typhi uses virulence factors to survive inside macrophages, key immune cells. Understanding these mechanisms is crucial for developing new typhoid fever treatments.
Area of Science:
- Immunology
- Microbiology
- Infectious Diseases
Background:
- Salmonella Typhi (S. Typhi) causes typhoid fever, a significant global health issue with millions of infections and over 100,000 deaths annually.
- Macrophages are crucial innate immune cells that S. Typhi targets, influencing disease development.
- S. Typhi possesses various virulence factors, including the Vi capsule, outer membrane proteins, and type III secretion systems.
Purpose of the Study:
- To review the role and molecular mechanisms of S. Typhi virulence factors.
- To understand how these factors enable intracellular survival within macrophages.
- To provide insights for future research and therapeutic interventions against typhoid fever.
Main Methods:
- Literature review of S. Typhi virulence factors and their interaction with macrophages.
- Analysis of molecular mechanisms of adhesion, invasion, nutrient acquisition, and immune evasion.
- Exploration of S. Typhi's counteraction of macrophage antimicrobial functions.
Main Results:
- S. Typhi virulence factors facilitate its survival and replication within macrophages.
- These factors mediate critical processes like immune evasion and nutrient acquisition.
- The interaction between S. Typhi and macrophages is central to systemic infection.
Conclusions:
- S. Typhi virulence factors are essential for overcoming macrophage defenses.
- Further research into these molecular mechanisms can guide the development of novel typhoid therapies.
- Targeting S. Typhi's interaction with macrophages offers a promising therapeutic strategy.
