Borrelia recurrentis - Classification, Morphology, Habitat, Culture, Antigen, Virulence factors

Introduction of Borrelia recurrentis

Borrelia recurrentis is the causative agent of relapsing fever and is transmitted via soft-shelled ticks. As it is an invasive bacterium, it enters the skin and causes disease.

Classification of Borrelia recurrentis

The classification of Borrelia recurrentis is:

Domain: Bacteria

Phylum: Spirochaetota

Class: Spirochaetia

Order: Spirochaetales

Family: Borreliaceae

Genus: Borrelia

Species: recurrentis

Morphology of Borrelia recurrentis

MOrphologically, Borrelia recurrentis is a gram-negative spirochete having unequal, loose 5-10 spiral coils with one or both pointed ends. It measures 8-20 μm x 0.2-0.4 μm and has 15-20 endofalgella per cell.

The bacteria are stained by Giemsa stain for microscopy and exhibit cork-screw-like motility and are seen as actively motile in fresh blood preparations.

Habitat of Borrelia recurrentis

Borrelia recurrentis habitats the bloodstream, spleen, liver, lungs, kidneys, and bone marrow of an infected person suffering from relapsing fever.

Culture of Borrelia recurrentis

Borrelia recurrentis is microaerophilic and requires 28-30°C as the optimum temperature. It requires complex nutritional requirements, thus it is difficult to grow on an artificial medium.

Borrelia recurrentis can be cultured in the chorioallantoic membrane (CAM) of the chick embryos, and intraperitoneal inoculation in lab animals. They appear early in the blood, and in the brain for a longer time.

Cell wall components, Antigenic structure of Borrelia recurrentis

Antigen variation is a unique property of Borrelia recurrentis. DNA rearrangement in linear plasmid present in Borrelia is responsible for Antigenic variation and causing relapse.

Virulence factors of Borrelia recurrentis

Antigenic shift or Ag variation is responsible for periodic febrile and afebrile stages observed in the relapsing fever (outer membrane protein differs). B. recurrentis can escape from the immune clearance of the host which is one of the most important virulence factors of Borrelia recurrentis.