What is a virulence protein?
The virulence factors of bacteria are typically proteins or other molecules that are synthesized by enzymes. These proteins are coded for by genes in chromosomal DNA, bacteriophage DNA or plasmids. Certain bacteria employ mobile genetic elements and horizontal gene transfer.
Why is M protein a virulence factor?
M protein is strongly anti-phagocytic and is the major virulence factor for group A streptococci (Streptococcus pyogenes). It binds to serum factor H, destroying C3-convertase and preventing opsonization by C3b. Bacteria like S. pyogenes, which possess M protein are classified in group A of the Lancefield system.
What are the main virulence factors of Streptococcus pyogenes?
GAS strains express many virulence factors including surface protein M, streptolysins, streptokinase, hyaluronidase, peptidoglycan, and teichoic acid. Protein M is considered as the main virulence factor, limiting phagocytosis, disturbing the function of complement, and being responsible for adhesion [4].
Why is LPS a virulence factor?
The virulence factors of the lipopolysaccharide of Shigella species bacteria include the endo- toxic activities of the lipid A component of the molecule and the ability of the polysaccharide chain- the core and the O-antigenic polysaccharide- to provide the bacterium with resistance to host defense mechanisms such as …
What is the function of M protein?
The M protein coats group A streptococci (GAS) and acts as the primary antigen and determinant of type-specific immunity. M is essential for GAS virulence, providing antiphagocytic functions critical to survival in human tissues and fluids.
What are the virulence factors of Streptococcus agalactiae?
Table 1
| Virulence factor | Mode of action | Genetic basis |
|---|---|---|
| Sialic acid capsular polysaccharide (CPS) | Prevents recognition of GBS through molecular mimicry of host-cell surface glycoconjugates | cpsA–L, neuA–D |
| Masks pro-inflammatory cell wall components | ||
| Superoxide dismutase (SodA) | Detoxifies singlet oxygen and superoxide | soda |
What are the virulence factors of Streptococcus?
Virulence factors of group A streptococci include (1) M protein and lipoteichoic acid for attachment; (2) a hyaluronic acid capsule that inhibits phagocytosis; (3) other extracellular products, such as pyrogenic (erythrogenic) toxin, which causes the rash of scarlet fever; and (4) streptokinase, streptodornase (DNase B …
Is LPS secreted?
Subsequent work showed that release of LPS from gram negative microbes does not necessarily require the destruction of the bacterial cell wall, but rather, LPS is secreted as part of the normal physiological activity of membrane vesicle trafficking in the form of bacterial outer membrane vesicles (OMVs), which may also …
What is the role of virulence factors in GTPase activity?
Virulence factors dealing in the role of GTPases. A major group of virulence factors are proteins that can control the activation levels of GTPases. There are two ways in which they act. One is by acting as a GEF or GAP, and proceeding to look like a normally eukaryotic cellular protein.
What is a virus virulence factor and how does it work?
Virulence factors are cellular structures, molecules and regulatory systems that enable microbial pathogens (bacteria, viruses, fungi, and protozoa) to achieve the following: colonization of a niche in the host (this includes movement towards and attachment to host cells) [1] [2]
What are the virulence factors of Streptococcus pyogenes and their roles?
Virulence factors of Streptococcus pyogenes and their roles. S. pyogenes produces various adhesins; Fibronectin (Fn) binding protein, lipoteichoic acids (LTA), M protein, Protein F etc. M Protein M protein is the major virulence factor of group A beta-hemolytic streptococci. It has anti-phagocytic and anti-complement properties.
How do bacterial virulence factors help bacteria survive?
These obtained bacterial virulence factors have two different routes used to help them survive and grow: The factors are used to assist and promote colonization of the host. These factors include adhesins, invasins, and antiphagocytic factors. The factors, including toxins, hemolysins and proteases, bring damage to the host.