Molecular typing of spp. in farmed and wild mammals reveals new host-serovar associations in New Zealand.

AIMS

To apply molecular typing to DNA isolated from historical samples to determine spp. infecting farmed and wild mammals in New Zealand.

MATERIALS AND METHODS

DNA samples used in this study were extracted from urine, serum or kidney samples (or spp. cultures isolated from them) collected between 2007 and 2017 from a range of domestic and wildlife mammalian species as part of different research projects at Massey University. Samples were included in the study if they met one of three criteria: samples that tested positive with a PCR for pathogenic ; samples that tested negative by PCR but were recorded as positive to PCR for pathogenic in the previous studies; or samples that were PCR-negative in all studies but were from animals with positive agglutination titres against serogroup Tarassovi. DNA samples were typed using PCR that targeted either the or genetic loci. The resulting amplicons were sequenced and typed relative to reference sequences.

RESULTS

We identified several associations between mammalian hosts and strains/serovars that had not been previously reported in New Zealand. strain Pacifica was found in farmed red deer () samples, serovars Balcanica and Ballum were found in wild red deer samples, serovar Copenhageni was found in stoats () and brushtail possums (), and was found in a ferret (). Furthermore, we reconfirmed previously described associations including dairy cattle with serovars Copenhageni and Pomona and serovars Ballum, Hardjo type bovis and strain Pacifica, sheep with serovar Pomona and serovar Hardjo type bovis, brushtail possum with serovar Balcanica, farmed deer with serovar Hardjo type bovis and hedgehogs () with serovar Ballum.

CONCLUSIONS

This study provides an updated summary of host- associations in New Zealand and highlights the importance of molecular typing. Furthermore, strain Pacifica, which was first identified as Tarassovi using serological methods in dairy cattle in 2016, has circulated in animal communities since at least 2007 but remained undetected as serology is unable to distinguish the different genotypes.

CLINICAL RELEVANCE

To date, leptospirosis in New Zealand has been diagnosed with serological typing, which is deficient in typing all strains in circulation. Molecular methods are necessary to accurately type strains of spp. infecting mammals in New Zealand.