Infections of swine caused by Leptospira serovars of serogroup Sejroe - possibilities of recognition with the use of PCR

The aim of this study was to confirm the presence of leptospires from the Sejroe serogroup in aborting seropositive sows and to identify which serovars of this serogroup are responsible for the infection. Serum and urine samples from 20 aborting sows, reared in five farms infected with the Sejroe serogroup, were submitted for examination. Serum samples were examined by the microscopic agglutination test (MAT) and urine samples by polymerase chain reaction (PCR) with primer sets specific for genus Leptospira, species L. borgpetersenii, the Sejroe serogroup, and the Hardjo-bovis genotype. All the examined serum samples showed titres specific to the Sejroe serogroup, ranging from 100 to 6400. PCR indicated the presence of Leptospira genus-specific DNA sequences in all urine samples examined. DNA sequences specific for both L. borgpetersenii and the Sejroe serogroup were found in 12 of these samples. Additionally, the sequences specific only for L. borgpetersenii were found in five urine samples and sequences for the Sejroe serogroup in two samples. The DNA sequence specific for the Hardjo-bovis genotype was not found in the urine samples. PCR confirmed the results of the MAT, displayed the presence of Leptospira sp. DNA in the urine of all the sows examined, proved the affinity of the detected leptospires to the Sejroe serogroup or at least to L. borgpetersenii, and excluded the Hardjo serovar as the reason for the infections described in the sows.