What is a pneumolysin toxin?

Pneumolysin is a cholesterol-dependent cytolysin (CDC) toxin that forms lytic pores in host membranes and mediates pneumococcal disease pathogenesis by modulating inflammatory responses.

Where is pneumolysin found?

Pneumolysin is present within the bacterial cytoplasm and because it does not have a N-terminal secretion signal sequence, lysis of the bacteria is essential for its release [9].

What does pneumolysin target?

Pore formation in host epithelial cell membranes: Pneumolysin binds to cholesterol in host epithelial cell membranes, where oligomers of pneumolysin molecules assemble to form 35- to 45-nm pores in the cell membrane, which results in lysis of the targeted cell. Pneumolysin is, therefore, cytotoxic to epithelial cells.

Is pneumolysin an exotoxin?

A major exotoxin of Streptococcus pneumoniae is pneumolysin (24). Pneumolysin is a multifunctional bacterial cytoplasmic protein of 53 kDa with a wide range of cytotoxic and proinflammatory properties, and it is an important determinant of pneumococcal virulence (28).

Is pneumolysin a hemolysin?

Pneumolysin was found to be produced by 112 of 113 clinical isolates of Streptococcus pneumoniae and to be an intracellular hemolysin.

How does pneumolysin affect the body?

Released pneumolysin will aid the bacteria during colonization by facilitating adherence to the host, during invasion by damaging host cells, and during infection by interfering with the host immune response. The presence of pneumolysin in sputum, urine, CSF and blood can be indicative of an S. pneumoniae infection.

Is pneumolysin secreted?

Pneumolysin is not actively secreted by S. pneumoniae owing to a lack of an N-terminal secretion signal (Walker et al., 1987). It is the only member of the CDC class to behave in this manner, though interestingly this trait is universally conserved across pneumococci (Martner et al., 2008).

What effect does pneumolysin have in humans?

Pneumolysin is a thiol-activated, membrane-damaging, multifunctional toxin and a known virulence factor of Streptococcus pneumoniae. The toxin can interfere with the functioning of both cellular and soluble components of the human immune system which protects against pneumococcal infection.

Does Streptococcus pneumoniae produce endotoxins or Exotoxins?

In addition to surface-associated virulence determinants, pneumococci secrete exotoxins. Two hemolysins have been described, the most potent of which is pneumolysin. Pneumolysin is a 53kDa protein that can cause lysis of host cells and activate complement.

Does Streptococcus pneumoniae have an endotoxin?

Endotoxin at concentrations of up to 5 micrograms/mL did not induce significant toxicity in any of the cells. Thus, pneumococci can induce toxicity in two brain cell types, microglia and astrocytes, and the pneumococcal cell wall appears to mediate toxicity.

Does Streptococcus pneumoniae produce hemolysin?

Streptococcus pneumoniae produces a second haemolysin that is distinct from pneumolysin. Microb Pathog. 1997 Mar;22(3):129-32. doi: 10.1006/mpat.

What is pneumolysin and how does it cause damage to the host?

Is pneumococcal same as pneumonia?

Pneumonia is a lung disease. Pneumococcal pneumonia, a kind of pneumonia, can infect the upper respiratory tract and can spread to the blood, lungs, middle ear, or nervous system. Pneumococcal pneumonia mainly causes illness in children younger than 5 years old and adults 65 years of age or older.

What are examples of endotoxins?

Endotoxin: Examples In bacteriology, this complex compound is also known as lipopolysaccharide and can be found on the outer membranes of bacteria like Escherichia coli, Salmonella shigella, Vibrio cholerae, and Haemophilus influenzae.

What type of pathogen is Streptococcus pneumoniae?

Streptococcus pneumoniae are lancet-shaped, gram-positive, facultative anaerobic bacteria with more than 100 known serotypes. Most S. pneumoniae serotypes can cause disease, but only a minority of serotypes produce the majority of pneumococcal infections.

Is E coli alpha or beta-hemolytic?

beta-hemolytic
E coli is a gram-negative bacillus that grows well on commonly used media. It is lactose-fermenting and beta-hemolytic on blood agar.

How many types of pneumococcal bacteria are there?

Key disease facts Pneumococcal disease includes a wide range of infections caused by different types of pneumococcus bacteria (Streptococcus pneumoniae). There are over 90 different types of these bacteria, and vaccines have been produced to protect against the types that cause the most disease.

What is the structure of pneumolysin?

Pneumolysin is a putative virulence factor of the Gram-positive bacteria Streptococcus pneumoniae. It is a pore-forming toxin of 53 kDa composed of 471 amino acids.

What is the role of Released pneumolysin in the pathogenesis of pneumonia?

Released pneumolysin will aid the bacteria during colonization, by facilitating adherence to the host, during invasion by damaging host cells, and during infection by interfering with the host immune response.

What is the function of pneumolysin in strep?

Pneumolysin is a putative virulence factor of the gram-positive bacteria Streptococcus pneumoniae. It is a pore-forming toxin of 53 kDa composed of 471 amino acids. It has a range of biological activity, including the ability to lyse and interfere with the function of cells and soluble molecules…