Effect of Porcine Epidemic Diarrhea Virus Infectious Doses on Infection Outcomes in Naïve Conventional Neonatal and Weaned Pigs.
Effect of Porcine Epidemic Diarrhea Virus Infectious Doses on Infection Outcomes in Naïve Conventional Neonatal and Weaned Pigs.
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DOI：
10.1371/journal.pone.0139266
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发表时间：
2015
期刊：
影响因子：
3.7
通讯作者：
Zhang J
中科院分区：
文献类型：
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作者：
Thomas JT;Chen Q;Gauger PC;Giménez-Lirola LG;Sinha A;Harmon KM;Madson DM;Burrough ER;Magstadt DR;Salzbrenner HM;Welch MW;Yoon KJ;Zimmerman JJ;Zhang J
猪流行性腹泻病毒（PEDV）在美国（U.S.）猪群于2013年4月首次出现，并迅速在全国范围内蔓延。然而，尚未公布关于不同猪模型中PEDV的最小感染剂量（MID）的信息。本研究的主要目的是确定PEDV在未经处理的常规新生仔猪和断奶仔猪中的口服最小感染剂量。将具有已知感染性滴度的美国毒性PEDV原型分离株（USA/IN 19338/2013）在病毒阴性细胞培养基中连续稀释10倍。将理论感染滴度为560 - 0.0056 TCID 50/ml的稀释液与培养基对照一起经口胃接种（10 ml/猪）至7组5日龄新生猪（每组n = 4）和7组21日龄断奶猪（每组n = 6）。在5日龄猪中，10 ml滴度为560-0.056 TCID 50/ml的接种物（对应于聚合酶链反应（PCR）循环阈值（Ct）值24.2-37.6）导致每组100%感染; 10 ml滴度为0.0056 TCID 50/ml（Ct>45）的接种物导致25%的接种猪感染。在21日龄猪中，接种10 ml，滴度为560-5.6 TCID 50/ml当接种10 ml，滴度为0.56-0.0056 TCID 50/ml时，（Ct值35.3 ->45）在研究条件下没有在任何猪中建立感染，如通过临床体征、PCR、组织病理学、免疫组织化学、和抗体反应。这些数据表明，PEDV感染剂量是年龄依赖性的，与断奶猪相比，新生猪的MID显著较低。当解释PEDV PCR结果的临床相关性和设计PEDV生物测定模型时，应考虑该信息。在新生儿中观察到如此低的MID也强调了母猪场严格生物安全和彻底清洁/消毒的重要性。
Porcine epidemic diarrhea virus (PEDV) was identified in the United States (U.S.) swine population for the first time in April 2013 and rapidly spread nationwide. However, no information has been published regarding the minimum infectious dose (MID) of PEDV in different pig models. The main objective of this study was to determine the oral minimum infectious dose of PEDV in naïve conventional neonatal piglets and weaned pigs. A U.S. virulent PEDV prototype isolate (USA/IN19338/2013) with known infectious titer was serially ten-fold diluted in virus-negative cell culture medium. Dilutions with theoretical infectious titers from 560 to 0.0056 TCID50/ml together with a medium control were orogastrically inoculated (10ml/pig) into 7 groups of 5-day-old neonatal pigs (n = 4 per group) and 7 groups of 21-day-old weaned pigs (n = 6 per group). In 5-day-old pigs, 10ml of inoculum having titers 560–0.056 TCID50/ml, corresponding to polymerase chain reaction (PCR) cycle threshold (Ct) values 24.2–37.6, resulted in 100% infection in each group; 10ml of inoculum with titer 0.0056 TCID50/ml (Ct>45) caused infection in 25% of the inoculated pigs. In 21-day-old pigs, 10ml of inoculum with titers 560–5.6 TCID50/ml (Ct 24.2–31.4) resulted in 100% infection in each group while 10ml of inoculum with titers 0.56–0.0056 TCID50/ml (Ct values 35.3 –>45) did not establish infection in any pigs under study conditions as determined by clinical signs, PCR, histopathology, immunohistochemistry, and antibody response. These data reveal that PEDV infectious dose is age-dependent with a significantly lower MID for neonatal pigs compared to weaned pigs. This information should be taken into consideration when interpreting clinical relevance of PEDV PCR results and when designing a PEDV bioassay model. The observation of such a low MID in neonates also emphasizes the importance of strict biosecurity and thorough cleaning/disinfection on sow farms.