Department of Animal and Food Sciences, University of Delaware, Newark, Delaware, USA.
Appl Environ Microbiol. 2013 Nov;79(22):7021-7. doi: 10.1128/AEM.01704-13. Epub 2013 Sep 6.
Human norovirus (huNoV) and hepatitis A virus (HAV) have been involved in several produce-associated outbreaks and identified as major food-borne viral etiologies. In this study, the survival of huNoV surrogates (murine norovirus [MNV] and Tulane virus [TV]) and HAV was investigated on alfalfa seeds during storage and postgermination. Alfalfa seeds were inoculated with MNV, TV, or HAV with titers of 6.46 ± 0.06 log PFU/g, 3.87 ± 0.38 log PFU/g, or 7.01 ± 0.07 log 50% tissue culture infectious doses (TCID50)/g, respectively. Inoculated seeds were stored for up to 50 days at 22°C and sampled during that storage period on days 0, 2, 5, 10, and 15. Following storage, virus presence was monitored over a 1-week germination period. Viruses remained infectious after 50 days, with titers of 1.61 ± 0.19 log PFU/g, 0.85 ± 0.21 log PFU/g, and 3.43 ± 0.21 log TCID50/g for MNV, TV, and HAV, respectively. HAV demonstrated greater persistence than MNV and TV, without a statistically significant reduction over 20 days (<1 log TCID50/g); however, relatively high levels of genomic copies of all viruses persisted over the testing time period. Low titers of viruses were found on sprouts and were located in all tissues as well as in sprout-spent water sampled on days 1, 3, and 6 following seed planting. Results revealed the persistence of viruses in seeds for a prolonged period of time, and perhaps of greater importance these data suggest the ease of which virus may transfer from seeds to sprouts and spent water during germination. These findings highlight the importance of sanitation and prevention procedures before and during germination.
人类诺如病毒（HuNoV）和甲型肝炎病毒（HAV）已涉及多起因食用受污染的农产品而引发的暴发事件，被认为是主要的食源性病毒病原体。本研究旨在探讨在苜蓿种子贮藏和萌发过程中，HuNoV 替代物（鼠诺如病毒[MNV]和杜兰病毒[TV]）和 HAV 的存活情况。用 MNV、TV 或 HAV 分别以 6.46±0.06 log PFU/g、3.87±0.38 log PFU/g 或 7.01±0.07 log 50%组织培养半数感染剂量（TCID50）/g 的滴度对苜蓿种子进行接种。接种后的种子在 22°C下贮藏，最长达 50 天，在此期间分别于 0、2、5、10 和 15 天进行采样。贮藏后，在 1 周的萌发期内监测病毒的存在情况。50 天后，MNV、TV 和 HAV 的病毒滴度分别为 1.61±0.19 log PFU/g、0.85±0.21 log PFU/g 和 3.43±0.21 log TCID50/g，仍具有感染性。HAV 的持久性大于 MNV 和 TV，20 天内无明显减少（<1 log TCID50/g）；然而，所有病毒的基因组拷贝在整个检测时间内都持续存在于较高水平。在种子发芽后第 1、3 和 6 天采集的幼苗和废水中，仍可检测到低滴度的病毒。结果表明，病毒在种子中可长时间存活，更重要的是，这些数据表明在发芽过程中，病毒可能很容易从种子转移到幼苗和废水中。这些发现强调了在发芽前和发芽期间进行卫生和预防措施的重要性。
