Department of Microbiology and Cell Biology, Montana State University, 2155 Analysis Drive, Bozeman, MT 59718, USA.
Montana State Veterinary Diagnostic Laboratory, 1911 West Lincoln Street, Bozeman, MT 59718, USA.
Viruses. 2022 Jun 28;14(7):1422. doi: 10.3390/v14071422.
Polymicrobial pneumonias occur frequently in cattle, swine, and sheep, resulting in major economic losses. Individual pathogens comprising these complex infections may be mild on their own but can instead exhibit synergism or increase host susceptibility. Two examples of such pathogens, () and influenza D viruses (IDVs), naturally infect domestic sheep. In sheep, the role of in chronic nonprogressive pneumonia is well-established, but the pathogenesis of IDV infection has not previously been studied. We utilized a specific-pathogen-free sheep flock to study the clinical response to IDV infection in naïve vs. -exposed lambs. Lambs were inoculated intranasally with or mock infection, followed after four weeks by infection with IDV. Pathogen shedding was tracked, and immunological responses were evaluated by measuring acute phase response and IDV-neutralizing antibody titers. While lamb health statuses remained subclinical, -exposed lambs had significantly elevated body temperatures during IDV infection compared to -naïve, IDV-infected lambs. Moreover, we found a positive correlation between prior burden, early-infection IDV shedding, and IDV-neutralizing antibody response. Our findings suggest that IDV infection may not induce clinical symptoms in domestic sheep, but previous exposure may promote mild IDV-associated inflammation.
多微生物性肺炎常发生于牛、猪和绵羊，造成重大经济损失。构成这些复杂感染的个别病原体本身可能较为温和，但可能会表现出协同作用或增加宿主易感性。两种此类病原体的例子是（）和流感 D 病毒（IDV），它们自然感染家养绵羊。在家养绵羊中， （）在慢性进行性肺炎中的作用已得到充分证实，但 IDV 感染的发病机制以前尚未研究过。我们利用无特定病原体绵羊群来研究对 IDV 感染的临床反应，涉及未感染的羔羊与（）暴露的羔羊。羔羊通过鼻腔接种或模拟感染，四周后再感染 IDV。跟踪病原体脱落情况，并通过测量急性期反应和 IDV 中和抗体滴度来评估免疫反应。尽管羔羊的健康状况仍处于亚临床状态，但与 IDV 感染的未暴露（）羔羊相比，（）暴露的羔羊在 IDV 感染期间体温明显升高。此外，我们发现先前的 负担、早期感染 IDV 脱落与 IDV 中和抗体反应之间呈正相关。我们的研究结果表明，IDV 感染可能不会在绵羊中引起临床症状，但先前的 暴露可能会促进轻度 IDV 相关炎症。
