Genomic characterisation of Leptospira inadai serogroup Lyme isolated from captured rat in Brazil and comparative analysis with human reference strain

Abstract

Leptospira inadai is classified as a species of the Leptospira intermediate group that has been poorly studied due to its apparent insignificance to human and animal health. Nevertheless, over the last two decades the species has been described in human cases in India and in carrier animals in Ecuador. Here, we present the first identification and genomic characterisation of L. inadai serogroup Lyme isolated from captured rodent in Brazil. Even though the M34/99 strain was not pathogenic for hamsters, it was able to establish renal colonisation. The M34/99 strain presented high similarity with L. inadai serogroup Lyme human reference indicating that animal strain could also infect humans, although it does not represent high risk of severe disease. An extrachromosomal sequence was also identified in M34/99 strain and presented high identity with previously described L. inadai phage LinZ_10, suggesting that phage-like extrachromosomal sequence may be another feature of this understudied species.

Development of a Novel Differential Duplex PCR for Pathogenic and Intermediate Leptospires: First Report of Intermediate Leptospira in Animal Sera in Argentina

“…Also, many recent studies revealed that species belonging to the intermediate clade may be associated with clinical disease in humans 13,14,18,26−28 . Despite these new ndings, little is known about the intermediate clade and its pathogenicity to animals and humans remains unclear, since it was not possible to reproduce the disease in a hamster model 19,20 .…”

“…In Latin America, there are very few studies about these species and its detection has been reported only in the following countries: Perú, Ecuador, Colombia, Argentina, Venezuela and Brazil 13,15,19,21,27,29 . In Argentina, the only study available reports the detection of intermediate leptospiral DNA in human samples 28 , but there is no further research until the present day, mainly due to the lack of an accurate diagnostic test.…”

“…Another hurdle that prevents obtaining more information about these leptospires is the complexity of the currently available diagnostic methods. Intermediate leptospires can be detected in clinical or environmental samples through isolation followed by genetic sequencing (e. g. whole genome sequencing or 16S rRNA gene sequencing) 19,26,27 , through qPCR, which requires expensive equipment 30 , or through several consecutive steps as nested-PCR followed by RFLP and sequencing 18 .…”