Round bodies, blebs and biofilms in Lyme disease

In an effort to better understand their significance, Corak and colleagues “grew B. burgdorferi spirochete, round body, bleb, and biofilm-dominated cultures and recovered their transcriptomes by RNAseq profiling.” Their non-spirochete morphotypes were induced by simple changes in growth conditions.

The authors described three pleomorphic forms as follows:

1. “Spherical B. burgdorferi cells with intact and flexible cell envelope enclosing numerous flagella are often termed as ‘round bodies.’”
2. “The so called “bleb” morphotype, is characterized by the formation of outer membrane vesicles (OMVs) on the surface of B. burgdorferi cells.”
3. “The B. burgdorferi biofilms are multicellular assemblies composed of spirochete, round body, and bleb cells embedded in a self-produced extracellular polysaccharide matrix.”

Corak and colleagues were able to generate these pleomorphic forms by modifying spirochetal cultures. They found that round bodies share similar expression profiles with spirochetes. Blebs and biofilms had different expression profiles with spirochetes.

“Taken together, we believe that many of the ongoing controversies related to Lyme disease pathogenesis and treatment strategies could be resolved by improving our understanding of B. burgdorferi biology and evolution, which for unclear reasons have not yet been explored.”

The authors postulated, “These regularities point to the possibility that bleb and biofilm morphotypes might be important in the dissemination and persistence of B. burgdorferi inside the mammalian host.”

They encouraged further research regarding the function of a large number of genes that might explain the pathogenesis of Lyme disease.

“Taken together, we believe that many of the ongoing controversies related to Lyme disease pathogenesis and treatment strategies could be resolved by improving our understanding of B. burgdorferi biology and evolution, which for unclear reasons have not yet been explored.”