engleski

Genetic affinities of Leptospira spp. isolates whithin the arhaic natural foci

Epizootiology/epidemiology of leptospirosis as well as taxonomy of its causative agents Leptospira spp. is extremely complex. There is a large number of already determined serovars with high degree of host adaptation. . Considering a strong relationship between prevalent serovars and their maintenance hosts we can assume that identification of certain natural focus (archaic, synatotropic or antropurgic) has a great influence in understanding epizootiology/epidemiology of leptospirosis in certain area and implementation of adequate control measures. Objective of this study was to determine genetic relatedness among circulating strains isolated from different sources (reservoirs and accidental hosts) within the same archaic natural foci of leptospirosis. Already described multilocus sequence typing (MLST) scheme based on DNA sequence identity of 6 genes (adk, icdA, rrs2, secY, LipL32, LipL41) (Ahmed et al., 2004) was used to type Leptospira isolates and to determine genetic affinities among them. MLST was conducted on 24 previously typed field isolates chosen from the archive of the Laboratory for leptospires, Faculty of Veterinary Medicine, University of Zagreb. Phylogenetic tree constructed with the concatenated sequences successfully separated investigated strains based on their genetic and serological status. Consecutive analysis determined that all genes, with exception of rrs2 encompass enough differences to discriminate isolates based on their genetic status. On the other hand, only secY gene contained enough variable sites to determine genomospecies and serological status of each isolate. Obtained data revealed smaller number of variable sites in all genes compared to those reported in previous studies, confirming an increased genetic relatedness of the investigated strains that was expected in archaic natural foci where basic patobiocenoses were formed a long time ago. In addition, chosen MLST approach or a simple PCR multiplication and sequencing of secY gene could be used as a convenient method for typing of Leptospira spp. strains if they are isolated within the same natural focus.

Leptospira; MLST; arhaic natural foci

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