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United States Department of Agriculture

Agricultural Research Service


item Palmer, Mitchell
item Cheville, Norman
item Jensen, Allen

Submitted to: American College of Veterinary Pathologists Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 11/17/1995
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: To determine the abortigenicity of the vaccine candidate, RB51, a rough mutant of the virulent strain 2308, 10 Polled Hereford heifers were inoculated i.v. in the sixth month of gestation. Heifers were euthanized and examined at 8 wks. post-inoculation (n=5) or at full term (n=5). Four of five heifers sampled at 8 wks. p.i. and 2/4 heifers at term had suppurative placentitis of the arcade zone with abundant intratrophoblastic bacteria as well as lymphoplasmacytic endometritis. In mammae, lymphoplasmacytic infiltrates in intersti- tial septae and suppurative infiltrates in alveoli were seen in 2/5 heifers at 8 wks. p.i. RB51 was cultured from all tissues in which lesions were seen. Four of five fetuses from heifers examined at 8 wks. p.i. and 2 full term calves had RB51 in liver, spleen, lung and bronchial lymph node but no lesions were seen. One heifer delivered a premature weak fetus 9 wks. p.i. The dam had severe suppurative placentitis as well as lymphoplasmacytic endometritis while the calf had mild multifocal interstitial hypercellularity with cells immuno- reactive for the macrophage marker CD68(EBM11). All tissues and fluids sampled from the heifer and calf contained RB51. These re- sults suggest that RB51 can colonize the bovine placenta, mammary gland and fetus and can induce placentitis which in turn can rarely lead to premature expulsion of the fetus.

Last Modified: 10/19/2017
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