The serological and genetic diversity of the Icterohaemorrhagiae serogroup circulating in the UK

English. Introduction: Strains of Leptospira interrogans belonging to two very closely related serovars, Icterohaemorrhagiae andCopenhageni, have been associated with disease in mammalian species and are the most frequently reported agents of humanleptospirosis. They are considered the most pathogenic serovars and represent more than half of the leptospires encountered insevere human infections. Material and Methods: Nineteen such isolates from the United Kingdom – human, domestic andwildlife species – were typed using three monoclonal antibodies (F12 C3, F70 C14 and F70 C24) in an attempt to elucidate theirepidemiology. They were further examined by restriction endonuclease analysis (REA), multiple-locus variable-number tandemrepeat analysis (MLVA) and lic12008 gene sequence analysis. Results: Monoclonal antibody F12 C3, which is highly specificfor Icterohaemorrhagiae and Copenhageni, confirmed that all the strains belonged to these two serovars. Sixteen strains wereidentified as Copenhageni and three as Icterohaemorrhagiae serovar. Only one restriction pattern type was identified, thusconfirming that REA is not able to discriminate between the Icterohaemorrhagiae and Copenhageni serovars. Variable-numbertandem-repeat analysis found three loci with differences in the repeat number, indicating genetic diversity between Britishisolates. Sequences of the lic12008 gene showed that all isolates identified as the Icterohaemorrhagiae serotype have a singlebase insertion, in contrast to the same sequences of the Copenhageni serotype. Conclusion: Copenhageni is the predominantserovar in the Icterohaemorrhagiae serogroup isolated in British Isles. There is a genetic diversity of MLVA patterns of theisolates but no genetic tool used in the study was able to determine serovars.

English. Leptospira, leptospirosis, Icterohaemorrhagiae, Copenhageni, animal pathogens

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