Leptospira interrogans complex - Virulence factors, Pathogenesis, Host immunity

Virulence factors of Leptospira interrogans complex

Leptospira interrogans directly invade and multiply in the blood and tissue. The main virulence factors determinant of Leptospira includes:

• Adhesin (Len A)

• Endotoxin, hemolysin, and lipase

• Endotoxin, hemolysin, and lipase

• sphingomyelinase C and H

• Fibronectin- binding protein for adhesion and invasion

• LPS in OMP

Pathogenesis of Leptospira interrogans complex

The pathogenesis and severity of leptospirosis, caused by Leptospira interrogans complex, depends on several factors such as:

1. host immunity

2. virulence of infecting strain

3. the number of infecting leptospires

Humans become infected through direct or indirect contact with the urine or blood of infected animals (rats, mice, dogs, pigs, and cattle). Leptospires enter the human host through breaks in the skin, mucous membrane, or conjunctivae.

Leptospira interrogans after entering rapidly invade the bloodstream and spread throughout all sites in the body as the CNS, kidney, liver, and skeletal muscles. It also has chemotaxis toward hemoglobin.

In the kidney, it causes interstitial necrosis, tubular necrosis, tubular damage, and hypovolemia resulting in renal failure. In the liver, it causes centrilobular necrosis and hepatocellular dysfunction leading to jaundice. In skeletal muscle, it causes edema and focal necrosis.

Host immunity of Leptospira interrogans complex

Humoral immunity against Leptospira interrogans complex plays an important role in the clearance of leptospires from circulation.