Borrelia-Coriaceae Sp-Nov - Putative Agent Of Epizootic Bovine Abortion

Genetic and phenotypic characteristics of the possible agent of epizootic bovine abortion, the Ornithodoros coriaceus spirochete, revealed that this organism is a new species of Borrelia. We propose the name Borrelia coriaceae for this species. The type strain of B. coriaceae is strain Co53 (= ATCC 43381). The guanine-plus- cytosine content of the deoxyribonucleic acid of the type strain was determined to be 32.4 mol% (thermal denaturation method). Epizootic bovine abortion (EBA) is an asymptomatic infection of cattle which frequently results in abortion during late pregnancy or in the birth of weak calves (7, 12). Apparently this disease has occurred in California for more than 60 years and has been responsible for heavy cattle losses since 1954. EBA is considered to be infectious since it can be transmitted by injecting tissue homogenates from diseased calves into cattle during their first pregnancy (13). Also, the prophylactic treatment of cattle with chlortetracy- cline has reduced the rate of EBA under field conditions, suggesting that a procaryotic microorganism(s) is the infec- tious agent (17). The feeding activities of the soft tick, Ornithodoros coriaceus, have been implicated in the epizoology of EBA (21), but an etiological agent had not been isolated before 1985. In 1985, Lane et al. (14) isolated a spirochete from 0. coriczceus and suggested that the spiro- chete may be causally related to EBA. The spirochete was present in 0.96% of the larvae, 8.26% of the nymphs, and 24% of the 0. coriaceus adults examined by these investi- gators. These workers also found the 0. coriaceus spiro- chete in every type of nymphal and adult tick tissue exam- ined and demonstrated that transovarial and transstadial passage do occur. More recently, Osebold et al. (19) re- ported the presence of spirochetes in fetal blood of calves presenting with lesions of EBA; these organisms were mor- phologically similar to spirochetes present in the tick 0. coriaceus. Ticks collected from areas where EBA was present were allowed to feed on cows, and these cows subsequently produced EBA-infected fetuses (19). Lane et al. (14) reported the 0. coriaceus spirochete to be highly motile and helical in form. The spirochete is 8 to 10 pm in length and 0.3 to 0.4 pm in diameter, with three to five serpentine waves. The cells have 11 to 15 periplasmic flagella (diameter, 11 to 14 nm) inserted in a random matrix of two to four rows along the long axis of the cell between the outer membrane and the protoplasmic cylinder. Monoclonal anti- body H9724, which is reactive with the periplasmic flagella of Borrelia (2), reacted with the 0. coriaceus spirochete and Borellia species but not with Spirochaeta, Treponema, or Leptospira spp. In addition, animal inoculation studies indi- cate that unlike Borrelia parkeri and Borrelia turicatae, the 0. coriaceus spirochete does not readily infect mice. Lane et al. concluded that this organism represents a hitherto