Adaptations

Being a parasite that is transmitted from one species to another, 

the environment around B. burgdorferi is not stable. 

Upon entering the host body, 

it must adapt to many environmental changes that it encounters as quickly as possible. 

Luckily for this pathogenic species, 

B. burgdorferi is capable of adjusting to different immune systems of different hosts.

One of the ways it does so is 

by changing its gene expression. 

Changes in its surroundings are detected by B. burgdorferi’s outer cell wall and are responded to with regulations of specific genes that would benefit the bacterium.

Fig.7. Illustration of
Prokaryotic Chromosome

Another key factor B. burgdorferi has that is advantageous to its adaptation is its high number of linear, and uncoiled, plasmids as opposed to the typical circular plasmids in bacteria. 

A plasmid is a DNA molecule, separate from the chromosomal DNA, carrying genes that aid in the survival of the organism, such as the antibiotic-resistant DNA. 

These plasmids contain duplicated genes, which allow the changes in the bacterium’s protein sequence to occur.

To counteract the different conditions found in different hosts, 

such as the temperature and acidic levels, 

B. burgdorferi produces specialized outer surface lipoproteins. 

An example of such proteins include heat shock proteins which assist in changes in temperature, as well as in preservation of the bacterium’s molecular structure in changing environment.

A certain type of lipid protein, Osps, helps the bacterium to establish colonies of itself within the host. 

OspA allows this endoparasite to remain in the tick’s gut as it feeds on the blood of another organism. 

Fig.8. OspA and OspC

OspA is crucial as it prevents the bacterium to be injected along with the blood. 

Decreasing the amount of OspA allows the bacterium to detach from the gut to flow into the tick’s salivary glands, with the help of another protein called OspC.

B. burgdorferi bacterium attaches itself to immunosuppressive proteins in the tick’s saliva that reduce the activation of the host’s immune system.

This helps the bacterium to invade the mammalian hosts that the ticks feed on.

Fig.9. "Entry of Borrelia in circulation and different tissue, induction of immuno-suppression with tick salivary protien, activation of the inflammatory and fibrinolytic systmes, and breaking the blood brain abrrier, which allows invasion of the CNS, resulting in neuroborreliosis."



Perhaps the most unique and significant advantage the bacteria in the genus Borrelia have against other bacteria are their lack of iron. 

The immune systems of hosts attempt to destroy the foreign invaders by depriving them of iron. 

However since these pathogens’ need for iron is already eliminated, they are able to bypass the defense system much more easily than others in different genera.

B. burgdorferi’s abilities to adapt to variety of environments and to protect itself from the hosts’ immune systems greatly contribute to its invasion efficiency.