To assess the effects of challenge dose and stage of gestation on infection and abortion, 35 elk were conjunctivally challenged with virulent Brucella abortus strain 2308 (S2308) during pregnancy. Seventeen elk were experimentally challenged early in the second trimester of gestation (December) with high (approximately 10⁸ CFU) or low challenge (approximately 10⁷ CFU) treatments having 8 and 9 pregnant elk, respectively. Other pregnant elk were experimentally challenged at a later challenge time (approximately early third trimester, February), with high and low challenge treatments having 8 and 10 elk, respectively. Conjunctival swabs from all animals were culture positive for the S2308 strain at 7 days after experimental challenge. All animals seroconverted on a B. abortus ELISA but optical density readings were not influenced (P > 0.05) by time of challenge or by challenge dosage. In the early challenge group, abortions occurred in 2 of 9 (22%) in the low challenge treatment and 3 of 8 (37%) in the high challenge treatment, whereas in the later challenge group, 1 of 8 (12.5%) in the low challenge treatment and 2 of 10 (20%) in the high challenge treatment aborted. The ability to recover B. abortus from samples obtained at necropsy did not differ (P > 0.05) between early and late challenges or between high and low challenge treatments. Despite the lack of abortions observed after experimental challenge, recovery from maternal tissues ranged from 50% (low dose, late challenge) to 77% (low dose, early challenge). Our data suggests that naïve elk do not abort as frequently after experimental infection with B. abortus strain 2308 as compared to similar data in cattle and bison.

为了评估激发剂量和妊娠阶段对感染和流产的影响，在妊娠期间，使用强毒布鲁氏流产菌株2308（S2308）结膜激发了35只麋鹿。在妊娠中期（12月）的早期对十七只麋鹿进行了实验性挑战（高（大约10 ⁸ CFU）或低挑战（大约10 ⁷ CFU）CFU）处理分别有8和9个怀孕麋鹿。其他妊娠麋鹿在较晚的挑战时间（大约在二月中下旬）进行了实验挑战，分别以高和低挑战的方式分别进行了8次和10次麋鹿的挑战。实验攻击后第7天，所有动物的结膜拭子的S2308菌株培养呈阳性。所有动物在流产芽孢杆菌ELISA中进行血清转化，但光密度读数不受影响（P> 0.05）的攻击时间或攻击剂量。在早期攻击组中，低攻击治疗组中有9人中有2人（22％）发生流产，在高挑战治疗组中有8人中有3人（37％）流产，而在后期攻击组中，8人中有1人（12.5％）流产。低挑战性治疗无效，高挑战性治疗中十分之二（20％）中止。从尸检中获得的样本中恢复流产双歧杆菌的能力在早期和晚期攻击之间或高和低攻击治疗之间没有差异（P > 0.05）。尽管在实验性攻击后未观察到流产，但从母体组织中恢复的比例为50％（低剂量，晚期攻击）至77％（低剂量，早期攻击）。我们的数据表明，幼稚的麋在实验性感染后不会流产与牛和野牛的相似数据相比，流产双歧杆菌菌株2308。