and Virulence Analysis of Species Isolated From Environments and Rodents in Leptospirosis Outbreak Areas in Malaysia.

The zoonotic disease leptospirosis is caused by pathogenic species of the genus . With the advancement of studies in leptospirosis, several new species are being reported. It has always been a query, whether species, serovars, and strains isolated from different geographical locations contribute to the difference in the disease presentations and severity. In an epidemiological surveillance study performed in Malaysia, we isolated seven novel intermediate and saprophytic species (is, , , , , , ) from environments and three pathogenic species from rodents ( strain HP364, strain SC295, strain HP358) trapped in human leptospirosis outbreak premises. To evaluate the pathogenic potential of these isolates, we performed an and virulence analysis. Environmental isolates and strain HP364 did not induce any clinical manifestations in hamsters. Strain SC295 caused inactivity and weight loss with histopathological changes in kidneys, however, all hamsters survived until the end of the experiment. Strain HP358 showed a high virulent phenotype as all infected hamsters died or were moribund within 7 days postinfection. Lungs, liver, and kidneys showed pathological changes with hemorrhage as the main presentation. analysis elucidated the genome size of strain HP358 to be larger than strains HP364 and SC295 and containing virulence genes reported in species and a high number of specific putative virulence factors. In conclusion, strain HP358 was highly pathogenic with fatal outcome. The constituent of genomes may determine the level of disease severity and that needs further investigations.