Sanitary status of oocytes and embryos collected from heifers experimentally exposed to Leptospira borgpetersenii serovar hardjobovis

In a preliminary trial and three experiments, a total of 30 Holstein heifer s were experimentally infected with a culture of Leptospira borgpetersenii serovar hardjobovis via one or more routes (uterine, cervical supraconjunct ival, intranasal) and oviductal and uterine fluids recovered postmortem or in vivo following superovulation with FSH. All routes of administration wer e effective in establishing Leptospira infection in the reproductive tract and Leptospira were identified in the oviductal and uterine fluids of all 3 0 heifers by microscopy. The incidence of infection was confirmed by positi ve identification of serum antibodies by the microscopic agglutination test (MAT). Twenty-one samples of the embryos (n = 59) recovered were cultured using bacteriological procedures and all tested negative for the infectious microorganism. Using polymerase chain reaction (PCR) assay, however, showe d that 29% (7/24) of morula and blastocyst stage embryos, and one out of 29 oocytes tested positive for the presence of leptospiral DNA. A single oocy te or embryo collected from the infected heifers was inoculated intravenous ly to 26 test heifers. None of the test heifers developed antibody titers t o Leptospira. It was concluded that, despite the presence of leptospires in the reproductive tract of donor animals and the association of leptospiral DNA with uterine stage embryos, the transmission of this disease is unlike ly to occur by transfer of in vivo produced embryos in the bovine. (C) 1998 Elsevier Science B.V. All rights reserved.