Molecular detection of Leptospira spp. in ovarian structures of naturally infected ruminants and its potential impact on reproductive function

Leptospirosis is a disease caused by spirochetes of the genus Leptospira and is widely recognized for its ability to infect a broad diversity of hosts. Infection by this agent can compromise reproductive efficiency, however, the involvement of ovarian structures in the dynamics of infection remains poorly understood. In this context, the present study aimed to investigate the presence of anti-Leptospira spp. antibodies and bacterial DNA in ovarian structures of cows and ewes naturally exposed to the pathogen. In total, blood, follicular fluid (FF), and corpus luteum (CL) samples were collected from 55 cows and 87 ewes. Serum samples were subjected to the Microscopic Agglutination Test (MAT), while ovarian structures were analyzed by PCR targeting the lipL32 gene. By MAT, 22/55 cows (40.0%) and 50/87 ewes (57.5%) presented anti-Leptospira spp. antibodies. A predominance of the Autumnalis (40.0%) and Sejroe (25.0%) serogroups was observed in cattle, whereas Sejroe (31.4%) predominated in sheep. Notably, molecular analysis revealed Leptospira spp. DNA in 2/55 (3.6%) CL samples from cows and in 19/87 (21.8%) CL and 8/87 (9.2%) FF samples from ewes, representing the molecular evidence of the agent in these ovarian compartments in naturally exposed ruminants. The detection of Leptospira spp. DNA suggests that the agent or its genetic material may reach temporary ovarian structures involved in reproductive physiology, however, the viability of the bacterium and its functional consequences remain to be determined.