Comparative genomics of Borrelia lusitaniae

Area of Science:

• Genomics and Microbiology
• Tick-borne bacterial pathogens
• Lyme disease research

Background:

• Human Lyme disease is a prevalent tick-borne illness caused by Borrelia burgdorferi sensu lato (BBSL) species.
• Borrelia lusitaniae, while less common, is isolated from human patients and uniquely utilizes reptiles as vertebrate reservoirs in Europe and North Africa.

Purpose of the Study:

• To sequence and analyze the complete genomes of three Borrelia lusitaniae isolates from distinct geographical lineages.
• To compare these genomes with other BBSL species, focusing on unique genetic features and their implications.

Main Methods:

• Whole-genome sequencing of three B. lusitaniae isolates: PotiB2T, PotiB3, and PoHL1.
• Bioinformatic analysis of genome structure, including chromosomes and plasmids.
• Comparative genomics to identify similarities and differences with other BBSL species.

Main Results:

• Complete genome sequences were obtained, revealing linear chromosomes and multiple plasmids (6-8 per isolate).
• A unique finding is the presence of partially degraded cp26 plasmids, which are dimers, unlike the standard cp26 plasmid found in other BBSL.
• These B. lusitaniae cp26 plasmids contain multiple, diverse ospC genes, a feature not observed in other analyzed BBSL species.

Conclusions:

• The B. lusitaniae genome architecture, particularly the cp26 dimer plasmids with multiple ospC genes, represents a significant divergence within the BBSL clade.
• The functional implications of these unique cp26 plasmids and multiple OspC types on bacterial virulence and host interactions remain to be elucidated.
• Further research is needed to understand how these genetic novelties influence the pathogenicity and epidemiological role of B. lusitaniae.