Edrington Thomas S, Arthur Terrance M, Loneragan Guy H, Genovese Kenneth J, Hanson Devin L, Anderson Robin C, Nisbet David J
United States Department of Agriculture, Agricultural Research Service, Food and Feed Safety Research Unit, 2881 F&B Road, College Station, TX 77841, USA.
United States Department of Agriculture, Agricultural Research Service, Roman L. Hruska U.S. Meat Animal Research Center, Clay Center, NE, USA.
Ther Adv Vaccines Immunother. 2020 Oct 5;8:2515135520957760. doi: 10.1177/2515135520957760. eCollection 2020.
is a common inhabitant of the ruminant gastrointestinal tract, where it often resides asymptomatically and may be shed into the feces. More recently it was discovered that may be contained within the peripheral, non-mesenteric lymph nodes, where it is impervious to in-plant pathogen control interventions and may serve as a source of -contamination of ground beef. Over the past 10 years considerable research effort has been expended at understanding how this pathogen gets to these lymph nodes, the duration of infection, and, most importantly, screening and developing potential intervention strategies that may be employed on farm prior to the animal being presented for slaughter.
Utilizing an experimental model of inoculation of bovine peripheral lymph nodes (PLNs), two pilot vaccine experiments were conducted to evaluate two vaccines: Newport Bacterial Extract (Experiment I) and Endovac-Bovi (Experiment II) on preventing acquisition by these nodes. In Experiment I, 4 months following the booster vaccination, 30 steers were inoculated with three serotypes intradermally: Newport, Montevideo, and Anatum administered to the right legs, left legs, and to the caudal thorax and abdomen, respectively. Cattle were inoculated every other day over the course of five days (three total inoculation events) and 6 and 12 days following the final inoculation, 16 and 14 head in each treatment were euthanized, respectively. In Experiment II, 12 head of Holstein steers were utilized. Seven days following the booster and weekly thereafter for 3 weeks (four total inoculation events), cattle were inoculated as above and euthanized 7 days following final inoculation. Right and left sub-iliac, popliteal and pre-scapular lymph nodes were collected in each experiment, weighed and cultured for .
In Experiment I, no treatment differences were observed in prevalence 6 days post-inoculation (necropsy 1). However, in vaccinated cattle at the second necropsy, a reduction ( = 0.05) in prevalence was observed in the sub-iliac and pre-scapular lymph nodes as well as when all nodes were evaluated collectively ( = 0.04). In Experiment II, the vaccine reduced ( = 0.03) prevalence in the right popliteal and tended ( = 0.09) to decrease prevalence in both popliteal lymph nodes.
Under these experimental conditions, the data generated provide evidence of a partial vaccine effect on within PLNs and indicate that further research may be warranted.
[病原体名称]是反刍动物胃肠道的常见寄居菌，通常无症状寄居，可能随粪便排出。最近发现，[病原体名称]可能存在于外周非肠系膜淋巴结中，在那里它不受植物内病原体控制干预措施的影响，可能成为碎牛肉受其污染的来源。在过去10年里，人们投入了大量研究精力来了解这种病原体如何到达这些淋巴结、感染持续时间，以及最重要的是，筛选和制定在动物屠宰前可在农场采用的潜在干预策略。
利用牛外周淋巴结接种[病原体名称]的实验模型，进行了两项试点疫苗实验，以评估两种[病原体名称]疫苗：纽波特细菌提取物（实验I）和牛用Endovac疫苗（实验II）对预防这些淋巴结感染[病原体名称]的效果。在实验I中，加强免疫接种4个月后，30头阉牛分别经皮接种三种[病原体名称]血清型：纽波特型、蒙得维的亚型和阿纳托姆型，分别接种于右腿、左腿以及尾胸部和腹部。在五天内每隔一天给牛接种一次（共三次接种），在最后一次接种[病原体名称]后的第6天和第12天，分别对每种处理中的16头和14头牛实施安乐死。在实验II中，使用了12头荷斯坦阉牛。在加强免疫接种7天后及此后每周一次，共进行3周（共四次接种），按上述方法给牛接种，并在最后一次接种后7天实施安乐死。在每个实验中收集左右髂下、腘窝和肩胛前淋巴结，称重并进行[病原体名称]培养。
在实验I中，接种后6天（尸检1）未观察到处理组间在[病原体名称]感染率上的差异。然而，在第二次尸检时，接种疫苗的牛中，髂下和肩胛前淋巴结以及对所有淋巴结进行综合评估时，[病原体名称]感染率均有所降低（P = 0.05）。在实验II中，该疫苗降低了右腘窝淋巴结的[病原体名称]感染率（P = 0.03），并且双侧腘窝淋巴结的感染率有降低趋势（P = 0.09）。
在这些实验条件下，所产生的数据为疫苗对牛外周淋巴结内[病原体名称]有部分预防效果提供了证据，并表明可能需要进一步研究。
