Hartard C, Leclerc M, Rivet R, Maul A, Loutreul J, Banas S, Boudaud N, Gantzer C
Université de Lorraine, Laboratoire de Chimie Physique et Microbiologie pour l'Environnement (LCPME), UMR 7564, Faculté de Pharmacie, Nancy, France.
CNRS, Laboratoire de Chimie Physique et Microbiologie pour l'Environnement (LCPME), UMR 7564, Nancy, France.
Appl Environ Microbiol. 2017 Dec 15;84(1). doi: 10.1128/AEM.01866-17. Print 2018 Jan 1.
Norovirus (NoV) is the leading cause of gastroenteritis outbreaks linked to oyster consumption. In this study, we investigated the potential of F-specific RNA bacteriophages (FRNAPH) as indicators of viral contamination in oysters by focusing especially on FRNAPH subgroup II (FRNAPH-II). These viral indicators have been neglected because their behavior is sometimes different from that of NoV in shellfish, especially during the depuration processes usually performed before marketing. However, a significant bias needs to be taken into account. This bias is that, in the absence of routine culture methods, NoV is targeted by genome detection, while the presence of FRNAPH is usually investigated by isolation of infectious particles. In this study, by targeting both viruses using genome detection, a significant correlation between the presence of FRNAPH-II and that of NoV in shellfish collected from various European harvesting areas impacted by fecal pollution was observed. Moreover, during their depuration, while the long period of persistence of NoV was confirmed, a similar or even longer period of persistence of the FRNAPH-II genome, which was over 30 days, was observed. Such a striking genome persistence calls into question the relevance of molecular methods for assessing viral hazards. Targeting the same virus (i.e., FRNAPH-II) by culture and genome detection in specimens from harvesting areas as well as during depuration, we concluded that the presence of genomes in shellfish does not provide any information on the presence of the corresponding infectious particles. In view of these results, infectious FRNAPH detection should be reconsidered as a valuable indicator in oysters, and its potential for use in assessing viral hazard needs to be investigated. This work brings new data about the behavior of viruses in shellfish, as well as about the relevance of molecular methods for their detection and evaluation of the viral hazard. First, a strong correlation between the presence of F-specific RNA bacteriophages of subgroup II (FRNAPH-II) and that of norovirus (NoV) in shellfish impacted by fecal contamination has been observed when both viruses are detected using molecular approaches. Second, when reverse transcription-PCR and culture are used to detect FRNAPH-II in shellfish, it appears that the genomes of the viruses present a longer period of persistence than infectious virus, and thus, virus genome detection fails to give information about the concomitant presence of infectious viruses. Finally, this study shows that FRNAPH persist at least as long as NoV does. These data are major arguments to reconsider the potential of FRNAPH as indicators of shellfish viral quality.
诺如病毒（NoV）是与食用牡蛎相关的肠胃炎暴发的主要病因。在本研究中，我们特别关注F特异性RNA噬菌体（FRNAPH）II亚组（FRNAPH-II），研究了其作为牡蛎中病毒污染指标的潜力。这些病毒指标一直被忽视，因为它们在贝类中的行为有时与诺如病毒不同，尤其是在通常上市前进行的净化过程中。然而，需要考虑一个显著的偏差。这个偏差是，在缺乏常规培养方法的情况下，诺如病毒通过基因组检测来靶向，而FRNAPH的存在通常通过感染性颗粒的分离来研究。在本研究中，通过使用基因组检测同时靶向这两种病毒，在从受粪便污染影响的欧洲各个捕捞区域采集的贝类中，观察到FRNAPH-II的存在与诺如病毒的存在之间存在显著相关性。此外，在净化过程中，虽然确认了诺如病毒的长期持续性，但观察到FRNAPH-II基因组的持续性相似甚至更长，超过30天。这种惊人的基因组持续性让人质疑评估病毒危害的分子方法的相关性。通过在捕捞区域的样本以及净化过程中通过培养和基因组检测靶向相同的病毒（即FRNAPH-II），我们得出结论，贝类中基因组的存在并不能提供关于相应感染性颗粒存在的任何信息。鉴于这些结果，应重新考虑将感染性FRNAPH检测作为牡蛎中一个有价值的指标，并且需要研究其在评估病毒危害方面的潜力。这项工作带来了关于病毒在贝类中行为的新数据，以及关于检测病毒和评估病毒危害的分子方法的相关性的新数据。首先，当使用分子方法检测这两种病毒时，在受粪便污染的贝类中观察到II亚组F特异性RNA噬菌体（FRNAPH-II）的存在与诺如病毒的存在之间存在很强的相关性。其次，当使用逆转录PCR和培养来检测贝类中的FRNAPH-II时，似乎病毒基因组的持续性比感染性病毒更长，因此，病毒基因组检测无法提供关于感染性病毒同时存在的信息。最后，这项研究表明FRNAPH的持续时间至少与诺如病毒一样长。这些数据是重新考虑FRNAPH作为贝类病毒质量指标潜力的主要论据。
