Document Type : Original Articles
Authors
1
Department of Microbiology, Razi Vaccine and Serum Research Institute, Agricultural Research, Education and Extension Organization (AREEO), Karaj, Iran
2
Department of Research and Development, Razi Vaccine and Serum Research Institute, Agricultural Research, Education and Extension Organization (AREEO), Karaj, Iran
10.22092/ari.2025.369930.3722
Abstract
Leptospirosis, caused by Leptospira spp., is a globally distributed reemerging zoonotic disease, predominantly prevalent in tropical, subtropical, temperate, and humid regions with high rainfall. Accurate identification of the causative agent is critical for effective diagnosis and disease control. This research was aimed at the genetic characterization and phylogenetic analysis of Leptospira serovars isolated in Iran by sequencing the secY gene.
Twenty-seven pathogenic and two non-pathogenic Leptospira serovars were obtained from the Reference Laboratory for Leptospira, Department of Microbiology, Razi Vaccine and Serum Research Institute, Karaj, Iran. Genomic DNA was extracted, and a 549-bp fragment of the secY gene was amplified using specific primers.
PCR amplification successfully identified the secY gene in all pathogenic serovars but not in the non-pathogenic L. biflexa. Sequence analysis revealed genetic similarity among pathogenic serovars ranging from 69.7% to 100%, highlighting the high discriminatory power of the secY gene. Serovars of the same serovar showed >99% sequence identity, whereas greater divergence was observed among different serovars.
This gene effectively differentiated all serovars, with those belonging to the same serovar exhibiting high sequence identity (>99%), while significantly greater divergence was observed among different serovars.
Phylogenetic analysis based on 26 reference serovars from established databases revealed that the majority of the studied serovars clustered with known Leptospira interrogans serovars. Additionally, two serovars were grouped with published sequences of L. borgpetersenii, L. alexanderi, L. santarosai, and L. weilii.
In conclusion, the secY gene exhibited considerable variability among pathogenic Leptospira serovars, demonstrating its utility as a molecular marker for accurate identification and phylogenetic classification of Leptospira serovars.
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