PT - JOURNAL ARTICLE AU - Cecilia Nieves AU - Antony T Vincent AU - Leticia Zarantonelli AU - Mathieu Picardeau AU - Frédéric J Veyrier AU - Alejandro Buschiazzo TI - Horizontal transfer of the <em>rfb</em> cluster in <em>Leptospira</em> is a genetic determinant of serovar identity AID - 10.26508/lsa.202201480 DP - 2023 Feb 01 TA - Life Science Alliance PG - e202201480 VI - 6 IP - 2 4099 - https://www.life-science-alliance.org/content/6/2/e202201480.short 4100 - https://www.life-science-alliance.org/content/6/2/e202201480.full SO - Life Sci. Alliance2023 Feb 01; 6 AB - Leptospira bacteria comprise numerous species, several of which cause serious disease to a broad range of hosts including humans. These spirochetes exhibit large intraspecific variation, resulting in complex tabulations of serogroups/serovars that crisscross the species classification. Serovar identity, linked to biological/clinical phenotypes, depends on the structure of surface-exposed LPS. Many LPS biosynthesis–encoding genes reside within the chromosomic rfb gene cluster. However, the genetic basis of intraspecies variability is not fully understood, constraining diagnostics/typing methods to cumbersome serologic procedures. We now show that the gene content of the rfb cluster strongly correlates with Leptospira serovar designation. Whole-genome sequencing of pathogenic L. noguchii, including strains of different serogroups, reveals that the rfb cluster undergoes extensive horizontal gene transfer. The rfb clusters from several Leptospira species disclose a univocal correspondence between gene composition and serovar identity. This work paves the way to genetic typing of Leptospira serovars, and to pinpointing specific genes within the distinct rfb clusters, encoding host-specific virulence traits. Further research shall unveil the molecular mechanism of rfb transfer among Leptospira strains and species.