Virulence Factors

Virulence factors are pathogen-produced extracellular enzymes or structural components of pathogens that aid in the colonization, multiplication, invasion, and evasion of host immune response.

Enzymes which acts as virulence factors

  1. Hyaluronidase: It promotes the spreading of the organisms in tissues by breaking down hyaluronic acid.
  2. Collagenase: It breaks down the collagen network supporting the tissues.
  3. Streptokinase: It is a fibrinolytic enzyme. Fibrin clots trap the microorganisms and limit their spread.
  4. Coagulase: It is a fibrin clotting enzyme and helps the organism to localize in a particular site, e.g., wounds.
  5. Hemolysins: Breakdown of RBCs.
  6. Lecithinases (or phospholipases):  Help the organism to break down phospholipid-lecithin.
  7. Leukocidins: Kills white blood cells.

Toxins

Toxins such as diphtheria toxin, cholera toxin, botulinum toxin, toxic shock syndrome toxin, tetanus toxin, botulinum toxin, etc., aids in the pathogenesis of respective pathogens.

Surface components

  1. Capsule: Antiphagocytic
  2. Lipopolysaccharide layer: Endotoxin
  3. Teichoic acid: Endotoxin, etc.

You can get detailed information on the virulence factors of each pathogen with their functions in the below-mentioned blog posts.

Bacillus anthracis: Properties, Pathogenesis, Lab Diagnosis

Bacillus anthracis: Properties, Pathogenesis, Lab Diagnosis

A potential biological weapon which causes important zoonotic disease called anthrax.

Streptococcus agalactiae (GBS): Properties, Pathogenesis, Lab Diagnosis

Streptococcus agalactiae (GBS): Properties, Pathogenesis, Lab Diagnosis

Streptococcus agalactiae (GBS), is a beta-hemolytic, CAMP test positive, gram-positive cocci. It can cause severe infection in newborns.

Listeria monocytogenes Virulence Factors

Listeria monocytogenes Virulence Factors

Internalin, listeriolysin O, phospholipases, etc are major virulence factors of Listeria monocytogenes.

Helicobacter pylori Virulence Factors: Roles in Pathogenesis

Helicobacter pylori Virulence Factors: Roles in Pathogenesis

Major virulence factors of H. pylori are flagella, urease enzyme, adhesins, VacA, CagA, OpiA, and DupA.

Staphylococcus aureus Virulence Factors

Staphylococcus aureus Virulence Factors

Major virulence factors of S. aureus are capsule, teichoic acid, protein A, enterotoxin, TSST-1, coagulase, hyaluronidase, etc.

Haemophilus Influenzae Virulence Factors

Haemophilus Influenzae Virulence Factors

Capsule, adhesion proteins, lipooligosaccharides, pili, IgA protease, and phase variations of H.influenzae play major roles in pathogenesis.

Streptococcus Pneumoniae Virulence Factors

Streptococcus Pneumoniae Virulence Factors

S. pneumoniae virulence factors include capsular polysaccharide, C carbohydrate antigen, pneumolysin, autolysin.

Streptococcus pyogenes Virulence Factors

Streptococcus pyogenes Virulence Factors

Major virulence factors of S.pyogenes are adhesions, M protein, hemolysins, pyrogenic exotoxins and spreading factors.

Neisseria gonorrhoeae: Disease, Pathogenesis, Lab Diagnosis

Neisseria gonorrhoeae: Disease, Pathogenesis, Lab Diagnosis

Neisseria gonorrhoeae is a gram-negative kidney-shaped diplococci. It causes gonorrhea, a sexually transmissted infection.

Neisseria meningitidis Virulence Factors

Neisseria meningitidis Virulence Factors

Major virulence factors of Neisseria meningitidis are capsular polysaccharide, outer membrane proteins, endotoxin and IgA protease.

Streptococcus pneumoniae (pneumococcus): Disease, Properties

Streptococcus pneumoniae (pneumococcus): Disease, Properties

Pneumococcus is lanceolate shaped gram-positive cocci and causes pneumonia and meningitis. Its is optochin sensitive and bile soluble.

Differences between Exotoxins and Endotoxins

Differences between Exotoxins and Endotoxins

Bacterial toxins are broadly divided into two general categories: exotoxins (secreted outside the cell) and endotoxins (LPS).

Escherichia coli (E. coli): Properties and Identification

Escherichia coli (E. coli): Properties and Identification

Normal flora of GI tract, E.coli is a major cause of urinary tract infections. It is lactose fermenting, gram negative bacilli.

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Pathogenicity Islands: Properties and Types

PAIs are large genomic islands located in the chromosome which codes for numerous virulence factors such as toxins, invasions, iron uptake.