Virus and Prion Diseases of Livestock Research Unit, National Animal Disease Center, USDA, Agricultural Research Service, Ames, IA 50010, USA.
Vet Microbiol. 2011 Dec 29;154(1-2):185-90. doi: 10.1016/j.vetmic.2011.06.016. Epub 2011 Jun 30.
Porcine circovirus type 2 (PCV2) is a single-stranded circular DNA virus that is the causative agent of porcine circovirus associated disease (PCVAD), a disease complex affecting swine around the world. Although this virus is believed to negatively affect the host's immune system, the mechanism by which PCV2 induces disease is not completely understood. This report describes a series of PCV2 experiments using the gnotobiotic pig model in which a relationship was demonstrated between abnormal leukograms and development of clinical disease in PCV2-infected pigs. When compared to control pigs the leukogram was characterized by a decrease in lymphocytes within 14 days post inoculation (dpi) followed by an increase in neutrophils 7-14 days later. No significant changes in the circulating monocyte, basophil, and eosinophil cell populations were detected. The combination of an absolute neutrophilia and lymphopenia produced a neutrophil/lymphocyte ratio that was predictive of clinical disease and was inversely correlated with the presence of neutralizing antibodies. Based on previous reports, the lymphopenia may be attributed to a direct cytolytic effect of the virus and could negatively affect the pig's immune response. The role of the neutrophilia in the pathogenesis of PCVAD in gnotobiotic pigs is unknown.
猪圆环病毒 2 型（PCV2）是一种单链环状 DNA 病毒，是引起猪圆环病毒相关疾病（PCVAD）的病原体，这种疾病在全球范围内影响猪。尽管人们认为这种病毒会对宿主的免疫系统产生负面影响，但 PCV2 诱导疾病的确切机制尚不完全清楚。本报告描述了一系列使用无菌猪模型进行的 PCV2 实验，该实验证明了异常白细胞计数与 PCV2 感染猪临床疾病发展之间存在关联。与对照猪相比，白细胞计数在接种后 14 天内表现为淋巴细胞减少，随后 7-14 天内中性粒细胞增加。循环单核细胞、嗜碱性粒细胞和嗜酸性粒细胞群体没有明显变化。绝对中性粒细胞增多和淋巴细胞减少产生的中性粒细胞/淋巴细胞比值可预测临床疾病，并与中和抗体的存在呈负相关。根据以往的报告，淋巴细胞减少可能归因于病毒的直接细胞溶解作用，并可能对猪的免疫反应产生负面影响。中性粒细胞增多在无菌猪 PCVAD 发病机制中的作用尚不清楚。
