Schumacher Loni L, Huss Anne R, Cochrane Roger A, Stark Charles R, Woodworth Jason C, Bai Jianfa, Poulsen Elizabeth G, Chen Qi, Main Rodger G, Zhang Jianqiang, Gauger Phillip C, Ramirez Alejandro, Derscheid Rachel J, Magstadt Drew M, Dritz Steve S, Jones Cassandra K
Department of Diagnostic Medicine/Pathobiology, Kansas State University, Manhattan, Kansas, United States of America.
Department of Grain Science and Industry, Kansas State University, Manhattan, Kansas, United States of America.
PLoS One. 2017 Nov 2;12(11):e0187309. doi: 10.1371/journal.pone.0187309. eCollection 2017.
New regulatory and consumer demands highlight the importance of animal feed as a part of our national food safety system. Porcine epidemic diarrhea virus (PEDV) is the first viral pathogen confirmed to be widely transmissible in animal food. Because the potential for viral contamination in animal food is not well characterized, the objectives of this study were to 1) observe the magnitude of virus contamination in an animal food manufacturing facility, and 2) investigate a proposed method, feed sequencing, to decrease virus decontamination on animal food-contact surfaces. A U.S. virulent PEDV isolate was used to inoculate 50 kg swine feed, which was mixed, conveyed, and discharged into bags using pilot-scale feed manufacturing equipment. Surfaces were swabbed and analyzed for the presence of PEDV RNA by quantitative real-time polymerase chain reaction (qPCR). Environmental swabs indicated complete contamination of animal food-contact surfaces (0/40 vs. 48/48, positive baseline samples/total baseline samples, positive subsequent samples/total subsequent samples, respectively; P < 0.05) and near complete contamination of non-animal food-contact surfaces (0/24 vs. 16/18, positive baseline samples/total baseline samples, positive subsequent samples/total subsequent samples, respectively; P < 0.05). Flushing animal food-contact surfaces with low-risk feed is commonly used to reduce cross-contamination in animal feed manufacturing. Thus, four subsequent 50 kg batches of virus-free swine feed were manufactured using the same system to test its impact on decontaminating animal food-contact surfaces. Even after 4 subsequent sequences, animal food-contact surfaces retained viral RNA (28/33 positive samples/total samples), with conveying system being more contaminated than the mixer. A bioassay to test infectivity of dust from animal food-contact surfaces failed to produce infectivity. This study demonstrates the potential widespread viral contamination of surfaces in an animal food manufacturing facility and the difficulty of removing contamination using conventional feed sequencing, which underscores the importance for preventing viruses from entering and contaminating such facilities.
新的监管和消费者需求凸显了动物饲料作为国家食品安全体系一部分的重要性。猪流行性腹泻病毒（PEDV）是首个被证实可在动物食品中广泛传播的病毒病原体。由于动物食品中病毒污染的潜在情况尚未得到充分表征，本研究的目的是：1）观察动物食品制造设施中病毒污染的程度，以及2）研究一种提议的方法——饲料测序，以减少动物食品接触表面的病毒污染。使用一株美国强毒PEDV分离株接种50千克猪饲料，通过中试规模的饲料制造设备进行混合、输送并装入袋中。对表面进行擦拭，并通过定量实时聚合酶链反应（qPCR）分析PEDV RNA的存在情况。环境拭子表明动物食品接触表面完全被污染（分别为0/40对48/48，阳性基线样本/总基线样本，阳性后续样本/总后续样本；P<0.05），非动物食品接触表面几乎完全被污染（分别为0/24对16/18，阳性基线样本/总基线样本，阳性后续样本/总后续样本；P<0.05）。用低风险饲料冲洗动物食品接触表面常用于减少动物饲料生产中的交叉污染。因此，使用同一系统生产了四批后续50千克无病毒猪饲料，以测试其对动物食品接触表面去污的影响。即使经过4次后续测序，动物食品接触表面仍保留病毒RNA（28/33阳性样本/总样本），输送系统比混合器污染更严重。一项测试动物食品接触表面灰尘传染性的生物测定未能产生传染性。本研究证明了动物食品制造设施中表面存在潜在的广泛病毒污染，以及使用传统饲料测序去除污染的困难，这凸显了防止病毒进入和污染此类设施的重要性。
