Replication of Streptococcus equi subspecies zooepidemicus infection in swine
Replication of Streptococcus equi subspecies zooepidemicus infection in swine
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DOI：
10.1016/j.vetmic.2021.109271
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发表时间：
2021-11-24
影响因子：
3.3
通讯作者：
Brockmeier, Susan L.
中科院分区：
文献类型：
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作者：
Hau, Samantha J.;Lantz, Kristina;Brockmeier, Susan L.
马链球菌是一种马的共生细菌，可引起包括人类在内的哺乳动物的感染。从历史上看，在中国和印度尼西亚，经济特区强毒株导致的猪死亡率很高，而在美国，疾病很少发生。最近，母猪的高死亡率事件被归因于北美的经济特区。这些死亡事件的经济特区分离株与中国暴发的一株分离株有很高的遗传相似性。综上所述，这可能表明经济特区对猪的健康构成了新的威胁。为了建立疾病模型并评估健康的常规饲养的猪对SEZ的易感性，我们用2019年死亡事件中的一种分离株来挑战母猪和五个月大的猪。用基因相似的豚鼠分离株或基因截然不同的马分离株挑战猪，以评估相对毒力。该猪分离株在挑战猪中引起严重的全身疾病，死亡率为100%。母猪的疾病表现与田间报告相似：嗜睡/抑郁、发热、不愿上升和高死亡率。豚鼠分离株也引起了严重的全身疾病；然而，大多数五个月大的猪都康复了。相比之下，马的分离株不会引起疾病，很容易从呼吸道中清除出去。总而言之，我们能够复制现场报道的疾病。结果表明，不同分离株之间的毒力存在差异，其中猪分离株的毒力最高。此外，我们生成了一个挑战模型，可用于未来的研究，以评估毒力因素和疾病预防策略。
Streptococcus equi subspecies zooepidemicus (SEZ) is a commensal bacterium of horses and causes infections in mammalian species, including humans. Historically, virulent strains of SEZ caused high mortality in pigs in China and Indonesia, while disease in the U.S. was infrequent. More recently, high mortality events in sows were attributed to SEZ in North America. The SEZ isolates from these mortality events have high genetic similarity to an isolate from an outbreak in China. Taken together, this may indicate SEZ is an emerging threat to swine health. To generate a disease model and evaluate the susceptibility of healthy, conventionally raised pigs to SEZ, we challenged sows and five-month-old pigs with an isolate from a 2019 mortality event. Pigs were challenged with a genetically similar guinea pig isolate or genetically distinct horse isolate to evaluate comparative virulence. The swine isolate caused severe systemic disease in challenged pigs with 100 % mortality. Disease manifestation in sows was similar to field reports: lethargy/depression, fever, reluctance to rise, and high mortality. The guinea pig isolate also caused severe systemic disease; however, most five-month-old pigs recovered. In contrast, the horse isolate did not cause disease and was readily cleared from the respiratory tract. In conclusion, we were able to replicate disease reported in the field. The results indicate differences in virulence between isolates, with the highest virulence associated with the swine isolate. Additionally, we generated a challenge model that can be used in future research to evaluate virulence factors and disease prevention strategies.