Madson D M, Magstadt D R, Arruda P H E, Hoang H, Sun D, Bower L P, Bhandari M, Burrough E R, Gauger P C, Pillatzki A E, Stevenson G W, Wilberts B L, Brodie J, Harmon K M, Wang C, Main R G, Zhang J, Yoon K J
Department of Veterinary Diagnostic and Production Animal Medicine, Iowa State University, Ames, IA, United States.
Department of Veterinary Diagnostic and Production Animal Medicine, Iowa State University, Ames, IA, United States.
Vet Microbiol. 2014 Nov 7;174(1-2):60-8. doi: 10.1016/j.vetmic.2014.09.002. Epub 2014 Sep 22.
Porcine epidemic diarrhea virus (PEDV) is associated with clinical diarrhea in naïve swine of all ages. This report describes timing of antibody generation and disease progression following infection with a US PEDV isolate by assessing fecal viral shedding, morphometric analysis of intestinal lesions, and magnitude of immunohistochemical staining. Sixty-three, 3-week-old pigs were randomly allocated into control (n=27) and challenged (n=36) groups. Challenged pigs were administered 1 mL of 1 × 10(3) PFU/mL of US/Iowa/18984/2013 PEDV isolate by oro-gastric gavage. Three control and four challenged pigs were necropsied on days post-inoculation (dpi) 1, 2, 3, 4, 7, and weekly thereafter, until study termination on dpi 35. Clinical disease, fecal shedding, body weight, and temperature were monitored during the study period. Diarrhea was observed in challenged pigs beginning for some on dpi 2, affecting a majority of pigs by dpi 6 and subsiding by dpi 10. Average daily gain was significantly lower (P<0.001) for one week post-infection in challenged pigs. PEDV was detected in feces by PCR on dpi 1 and continued in a subset of pigs until dpi 24. PEDV-specific antigen was detected in villous enterocytes of challenged pigs by immunohistochemistry (IHC) on dpi 1, 2, 3, 4, 7, and 14. Microscopic lesions included severe diffuse atrophic enteritis with significantly reduced (P<0.001) villous length observed on dpi 3, 4, and 7. Under the conditions of this study, fecal shedding of PEDV and IHC staining can precede and continue beyond the observation of clinical signs, thus increasing the risk of viral transmission.
猪流行性腹泻病毒（PEDV）与各年龄段初生猪的临床腹泻有关。本报告通过评估粪便病毒排出情况、肠道病变的形态计量分析以及免疫组织化学染色强度，描述了美国PEDV分离株感染后抗体产生的时间和疾病进展情况。将63头3周龄仔猪随机分为对照组（n = 27）和攻毒组（n = 36）。通过口胃管饲法给攻毒组仔猪接种1 mL浓度为1×10(3) PFU/mL的美国/爱荷华/18984/2013 PEDV分离株。在接种后第1、2、3、4、7天以及此后每周对3头对照仔猪和4头攻毒仔猪进行剖检，直至接种后第35天研究结束。在研究期间监测临床疾病、粪便排出、体重和体温。攻毒组仔猪在接种后第2天开始出现腹泻，到第6天大多数仔猪受影响，第10天腹泻症状消退。攻毒组仔猪在感染后一周内平均日增重显著降低（P<0.001）。通过PCR在接种后第1天在粪便中检测到PEDV，并在一部分仔猪中持续检测到第24天。通过免疫组织化学（IHC）在接种后第1、2、3、4、7和14天在攻毒组仔猪的绒毛肠上皮细胞中检测到PEDV特异性抗原。显微镜下病变包括严重的弥漫性萎缩性肠炎，在接种后第3、4和7天观察到绒毛长度显著缩短（P<0.001）。在本研究条件下，PEDV的粪便排出和IHC染色可先于临床症状出现并在临床症状消失后仍持续存在，从而增加了病毒传播的风险。
