Polymerase chain reaction for detection of Borrelia coriaceae, putative agent of epizootic bovine abortion.

The nucleotide sequence of a chromosomally encoded antigen-expressing gene of Borrelia coriaceae was determined and used as a target for the polymerase chain reaction (PCR). Two primer sets were designed specifying the amplification of 269- and 701-bp DNA fragments. Primer set I, producing the short amplicon, was tenfold more sensitive than primer set II. As little as 10 fg of purified B coriaceae DNA could consistently be detected. The PCR assays, containing controlled numbers of whole spirochetes, allowed detectable amplification of 2 to 10 organisms. An internal, nonradioactively labeled gene-specific probe verified specificity of the PCR amplicons. Neither primer set cross-reacted with other related spirochetes. This PCR assay was adapted and found suitable for identification of B coriaceae in biological samples, such as blood and thymus. Evidence for presence of B coriaceae in biological samples was not found in tissue samples obtained from experimentally infected cows and their fetuses. These data failed to establish a definite association between B coriaceae and epizootic bovine abortion.