Sequence of Leptospira santarosai serovar Shermani genome and prediction of virulence-associated genes

Leptospirosis, a widespread zoonosis, is a re-emerging infectious disease caused by pathogenic Leptospira species. In Taiwan, Leptospira santarosai serovar Shermani is the most frequently isolated serovar, causing both renal and systemic infections. This study aimed to generate a L. santarosai serovar Shermani genome sequence and categorize its hypothetical genes, particularly those associated with virulence. The genome sequence consists of 3,936,333 nucleotides and 4033 predicted genes. Additionally, 2244 coding sequences could be placed into clusters of orthologous groups and the number of genes involving cell wall/membrane/envelope biogenesis and defense mechanisms was higher than that of other Leptospira spp. Comparative genetic analysis based on BLASTX data revealed that about 73% and 68.8% of all coding sequences have matches to pathogenic L. interrogans and L. borgpetersenii, respectively, and about 57.6% to saprophyte L. biflexa. Among the hypothetical proteins, 421 have a transmembrane region, 172 have a signal peptide and 17 possess a lipoprotein signature. According to PFAM prediction, 32 hypothetical proteins have properties of toxins and surface proteins mediated bacterial attachment, suggesting they may have roles associated with virulence. The availability of the genome sequence of L. santarosai serovar Shermani and the bioinformatics re-annotation of leptospiral hypothetical proteins will facilitate further functional genomic studies to elucidate the pathogenesis of leptospirosis and develop leptospiral vaccines.