Genetic structure and diversity of rfb locus of pathogenic species of genus Leptospira

Considered a globally important zoonotic bacterial disease, leptospirosis affects both humans and commercially important animals. It is transmitted through direct or indirect exposure to the urine of infected animals and is a major public health challenge in regions with heavy rainfall, floods, and poor socioeconomic conditions. The genus Leptospira has 67 species, which can be grouped into pathogenic and saprophytic groups. Serological classification based on antigenic characteristics is important in epidemiology and clinical analysis but is laborious, requires infrastructure and specialized labor, and takes days to obtain results. In this study, we aimed to find genetic patterns associated with the serological classification of Leptospira to propose molecular markers for classifying Leptospira samples at the serogroup level. For this, we used genomic data of 722 samples distributed in 67 species in public databases and compared the gene composition of their rfb locus. Clustering analysis was able to group samples into five major classes that share similarities in both the serological and genetic composition of the rfb locus. We also identified some syntenic blocks in the internal region of the rfb locus and patterns of presence and absence of these blocks which can be used to determine the serogroup of a sample. Our findings can assist the development of molecular strategies for the serological identification of Leptospira samples, which could be more rapid and accurate than the current method.