Characterization of leptospiral DNA in the follicular fluid of non‐pregnant cows

Bovine leptospirosis is mainly characterized by reproductive disorders. Contamination of the oocyte was previously demonstrated in vitro, resulting in some apparent damage. However, it is not clear whether it occurs under natural conditions. The present study aimed to characterize the presence of pathogenic LeptospiraDNA in the ovarian follicles of non‐pregnant cows. Follicular fluid samples were collected from 65 animals and subjected to lipL32 PCR and secY sequencing. In total, seven of 65 (10.8%) were positive, indicating a possible early infection of the oocyte. Moreover, secY sequencing identified L. interrogansand L. santarosai, both very closely related to bovine strains from the Sejroe serogroup (Hardjoprjitno and Guaricura). We demonstrated that ovarian follicles can also be infected. It was hypothesised that ovarian infection can contribute to embryonic death, causing reproductive failure and estrus repetition. In the present study, we show that the organism identified in the follicle is closely related to one that is known to be associated with reproductive disorders.