US Geological Survey, Western Fisheries Research Center, Marrowstone Marine Field Station, Nordland, WA 98328, USA.
Dis Aquat Organ. 2021 May 27;144:245-252. doi: 10.3354/dao03595.
Processes that allow viral hemorrhagic septicemia (VHS) virus to persist in the marine environment remain enigmatic, owing largely to the presence of covert and cryptic infections in marine fishes during typical sub-epizootic periods. As such, marine host reservoirs for VHS virus have not been fully demonstrated, nor have the mechanism(s) by which infected hosts contribute to virus perpetuation and transmission. Here, we demonstrate that after surviving VHS, convalesced Pacific herring continue to shed virus at a low rate for extended periods. Further, exposure of previously naïve conspecific sentinels to this shed virus can result in infections for at least 6 mo after cessation of overt disease. This transmission mechanism was not necessarily dependent on the magnitude of the disease outbreak, as prolonged transmission occurred from 2 groups of donor herring that experienced cumulative mortalities of 4 and 29%. The results further suggest that the virus persists in association with the gills of fully recovered individuals, and long-term viral shedding or shedding relapses are related to cooler or decreasing water temperatures. These results provide support for a new VHS virus perpetuation paradigm in the marine environment, whereby the virus can be maintained in convalesced survivors and trafficked from these carriers to sympatric susceptible individuals.
病毒出血性败血症（VHS）病毒在海洋环境中持续存在的过程仍然是个谜，主要是因为在典型的亚流行期间，海洋鱼类中存在隐性和隐匿性感染。因此，尚未充分证明 VHS 病毒的海洋宿主储主，也未证明受感染宿主对病毒持续存在和传播的机制。在这里，我们证明，在幸存 VHS 后，康复的太平洋鲱鱼会在很长一段时间内以低速率继续排出病毒。此外，先前未经感染的同种哨兵鱼暴露于这种脱落的病毒中，至少在显性疾病停止后 6 个月内会导致感染。这种传播机制不一定依赖于疾病爆发的严重程度，因为来自经历累计死亡率为 4%和 29%的两组供体鲱鱼的长时间传播都发生了。结果进一步表明，病毒与完全康复个体的鳃相关联而持续存在，并且长期病毒脱落或脱落复发与较冷或水温下降有关。这些结果为海洋环境中 VHS 病毒持续存在的新范例提供了支持，即病毒可以在康复幸存者中维持，并从这些携带者传播到同域易感个体。
