RT Journal Article SR Electronic T1 Horizontal transfer of the rfb cluster in Leptospira is a genetic determinant of serovar identity JF Life Science Alliance JO Life Sci. Alliance FD Life Science Alliance LLC SP e202201480 DO 10.26508/lsa.202201480 VO 6 IS 2 A1 Cecilia Nieves A1 Antony T Vincent A1 Leticia Zarantonelli A1 Mathieu Picardeau A1 Frédéric J Veyrier A1 Alejandro Buschiazzo YR 2023 UL https://www.life-science-alliance.org/content/6/2/e202201480.abstract 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.