Related Experiment Video
Updated: Jul 2, 2026
07:15
Invasion of Human Cells by a Bacterial Pathogen
Published on: March 21, 2011
Pilus backbone contributes to group B Streptococcus paracellular translocation through epithelial cells.
Alfredo Pezzicoli1, Isabella Santi, Peter Lauer
1Novartis Vaccines and Diagnostics, Siena, Italy.
The Journal of Infectious Diseases
|August 13, 2008
Summary
Group B Streptococcus (GBS) uses pili to spread through epithelial cells. Pili located between cells aid bacterial translocation, suggesting a dual role in GBS dissemination.
Area of Science:
- Microbiology
- Cell Biology
- Infectious Diseases
Background:
- Group B Streptococcus (GBS) is a significant pathogen that invades host tissues.
- Previous research indicated GBS traverses epithelial barriers via a paracellular route.
Purpose of the Study:
- To investigate the role of GBS pili in crossing the epithelial barrier.
- To elucidate the mechanism of GBS translocation through differentiated human epithelial cells.
Main Methods:
- Utilized deletion mutants of GBS pilus backbone and ancillary proteins.
- Employed 3-dimensional confocal microscopy to visualize pilus localization during bacterial translocation.
- Developed and used a novel in vitro model simulating GBS infection against gravitational forces.
Main Results:
- Deletion of the pilus backbone protein reduced GBS transcytosis despite maintaining adhesiveness.
- A mutant with altered pilus ancillary protein and reduced adhesiveness showed similar translocation to wild-type GBS.
- Confocal microscopy revealed pili positioned in the intercellular space ahead of translocating bacteria.
Conclusions:
- GBS pili play a complex, dual role in bacterial dissemination.
- Pilus components are critical for efficient transcytosis across epithelial barriers.
- Understanding pilus function is key to developing strategies against GBS infections.
Related Concept Videos
01:28Fimbriae, Pili, and Axial Filaments
Fimbriae and pili are specialized bacterial surface structures that play pivotal roles in adhesion, genetic exchange, and motility. Composed primarily of pilin protein, these hairlike appendages are crucial for bacterial survival and pathogenicity in various environments.Fimbriae: Adhesion and PathogenicityFimbriae are fine, filamentous structures measuring 2–10 nanometers in diameter and are densely distributed on the bacterial cell surface. They facilitate bacterial adhesion to abiotic...
01:25Colonisation of Pathogens
Pathogen colonization of host tissues is a critical step in the development of infectious diseases. Various pathogenic microorganisms, including bacteria, fungi, viruses, and protozoa, have evolved complex strategies to attach to, invade, and persist within host environments. These mechanisms enable pathogens to establish infections, evade immune responses, and resist antimicrobial treatments.Attachment to Host CellsIn bacteria, colonization typically begins with adherence to host epithelial...
01:29Cytoskeletal Proteins in Bacteria
Bacterial cells were initially considered simple, randomly organized structures lacking a cytoskeleton. However, the discovery of cytoskeleton homologs in bacteria led to the change of this opinion. Bacterial cytoskeletal filaments regulate the cell shape, cell polarity, cell division, and partitioning of plasmids during cell division. It was later discovered that bacterial cytoskeletal proteins, mainly actin and tubulin homologs, are diverse compared to their eukaryotic counterparts. On the...
01:20Determinants of Bacterial Pathogenicity and Virulence
Pathogenic bacteria employ a variety of strategies to establish infections, including the secretion of extracellular enzymes that act as potent virulence factors. These enzymes facilitate bacterial colonization of host tissues and help evade immune surveillance. By targeting structural components of host tissues and interfering with immune mechanisms, these enzymes play a pivotal role in disease progression.Extracellular Enzymes Facilitating Tissue Invasion: Several bacterial pathogens secrete...
01:27Streptococcal Pharyngitis
Streptococcal pharyngitis, commonly known as “strep throat,” is an acute infection of the oropharyngeal tissues caused by the Gram‑positive Group A Streptococcus (Streptococcus pyogenes). Transmission occurs primarily through respiratory droplets expelled during coughing, sneezing, or talking.Mechanisms of Host Entry and Immune EvasionUpon entering the host, S. pyogenes adheres to the mucosal epithelial cells of the pharynx via surface proteins, notably lipoteichoic acid and the antiphagocytic...
01:19Mechanism of Conjugation
Bacterial conjugation is a mechanism of horizontal gene transfer that enables the exchange of genetic material between bacterial cells through direct contact. This process is facilitated by a donor cell carrying a conjugative plasmid, which encodes genes necessary for pilus formation, DNA replication, and transfer. The conjugative plasmid plays a central role in initiating and executing the transfer of genetic material.The tra region of the conjugative plasmid encodes proteins responsible for...