Siju JosephDIVYA D.2023-03-012023-03-012021-12-30https://krishikosh.egranth.ac.in/handle/1/5810194639Submitted in partial fulfilment of the requirement for the degree of MASTER OF VETERINARY SCIENCE in Veterinary MicrobiologyLeptospirosis is an emerging and re-emerging zoonotic disease endemic in Kerala and close monitoring of emerging serovars is essential, for adopting appropriate control strategies. Multi-Locus Sequence Typing (MLST) is reported to be a less expensive serovar level identification tool as compared to much costly and cumbersome methods like whole genome sequencing. A study was undertaken to isolate Leptospira from infected animals and rats and to perform MLST for the serovar level identification. The seroprevalence recorded using MAT was 20.97 per cent. Among the 205 samples, 15 were confirmed to have the presence of pathogenic Leptospira using G1 and G2 genus specific PCR. However, when these were inoculated to EMJH semi-solid medium, only ten isolates were obtained. The ten isolates were further subjected to secY, icdA and GyraseB PCR and sequenced. The obtained sequences were analysed using BLAST and the isolates demonstrated more than 98.5 per cent homology. The sequences obtained from the isolates were fed into specified MLST database and using the Leptospira MLST scheme-3, the allelic profile and sequence type were generated. Among the ten isolates, nine could be identified at the serovar level. The serovar of the isolates identified by MLST were perfectly matching with that of MAT. The MLST results obtained in the present study indicated that the isolates S24 and S 33 belonged to the same serovar Canicola, S40 and S47 were Sejroe and S55, S71, S27, S69 and S19 were Pomona, Australis, Autumnalis, Icterohaemorraghiae and Bataviae, respectively. It was concluded that MLST could be used as an alternative to the whole genome sequencing and other cumbersome procedures for the serovar level identification of Leptospira. Further, it is recommended that for getting more promising results in MLST, the sequence data from at least seven genes need to be employed.EnglishThesis