Graduate School of Medicine and Veterinary Medicine, Miyazaki, Japan; Department of Veterinary Pathology, Miyazaki, Japan.
Department of Veterinary Pathology, Miyazaki, Japan.
J Comp Pathol. 2022 Sep;197:23-34. doi: 10.1016/j.jcpa.2022.06.006. Epub 2022 Aug 10.
Porcine respiratory disease complex, which is caused by a combination of pathogens, including swine influenza A virus (SIV) and porcine reproductive respiratory syndrome virus (PRRSV), results in significant economic losses in pig production systems. Nasopharynx-associated lymphoid tissue (NALT) plays an important role in the uptake of pathogens and defence of the nasal mucosa in rodents and humans. We characterized NALT M cells in pigs and detected SIV antigen and PRRSV nucleic acid in NALT using histopathological, immunohistochemical and in-situ hybridization analyses. All SIV- and PRRSV-positive cases examined had suppurative nasopharyngitis and pneumonia. M cells were detected by immunohistochemistry and the distribution of M cells showed an increase in the middle section of NALT. SIV antigen was detected in M cells and PRRSV nucleic acid was demonstrated in the cytoplasm of macrophages in NALT. We believe that SIV and PRRSV infection in the upper respiratory tract induces local immunosuppression and these results confirm that swine NALT is a location for virus replication and may be strongly associated with the development of pneumonia in pigs.
猪呼吸道疾病综合征是由多种病原体引起的，包括猪流感 A 病毒（SIV）和猪繁殖与呼吸综合征病毒（PRRSV），给养猪业造成了重大的经济损失。鼻相关淋巴组织（NALT）在啮齿动物和人类中对病原体的摄取和鼻腔黏膜的防御起着重要作用。我们对猪的 NALT 中的 M 细胞进行了特征描述，并通过组织病理学、免疫组织化学和原位杂交分析检测了 NALT 中的 SIV 抗原和 PRRSV 核酸。所有检测到的 SIV 和 PRRSV 阳性病例均有化脓性鼻咽炎和肺炎。通过免疫组织化学检测到 M 细胞，M 细胞的分布显示 NALT 的中段增加。在 NALT 的 M 细胞中检测到 SIV 抗原，在 NALT 的巨噬细胞质中检测到 PRRSV 核酸。我们认为，上呼吸道的 SIV 和 PRRSV 感染会导致局部免疫抑制，这些结果证实猪的 NALT 是病毒复制的部位，可能与猪肺炎的发生密切相关。
