Department of Aqualife Medicine, Chonnam National University, Yeosu 550-749, Republic of Korea.
Department of Aqualife Medicine, Chonnam National University, Yeosu 550-749, Republic of Korea.
Virus Res. 2019 Nov;273:197738. doi: 10.1016/j.virusres.2019.197738. Epub 2019 Sep 4.
Viral hemorrhagic septicemia (VHS) causes serious economic loss in olive flounder aquaculture industry in Korea. Water temperature is known to play a critical role in VHS disease outbreak. Here, we assessed the potential efficacy of VHSV immersion treatment in relation to resistance conferred at differential water temperatures in olive flounder. VHSV acquired resistance was compared between formalin-killed VHSV immersion treatment and live VHSV immersion treatment at three different water temperatures viz., 10 °C, 17 °C, and 20 °C. At 10 °C, cumulative mortality was around 80% in live VHSV immersed group while 30% cumulative mortality was observed in formalin-killed VHSV treated group. After 4 weeks, surviving olive flounder at 17 °C and 20 °C were challenged with VHSV at 10 °C following which the VHS outbreaks took place at host susceptible water temperature. For the pre-treated flounder at 17 °C, survival rates were 80% and 30% after challenge at 10 °C in live VHSV immersed group and formalin-killed VHSV immersed group, respectively. Whereas, the pre-treated flounder at 20 °C showed survival rate of 75% and 20% after challenge at 10 °C in live VHSV immersed group and formalin-killed VHSV immersed group, respectively. Our results propose the fact that live VHSV immersion using non-susceptible water temperature has the potential to protect olive flounder against VHSV infection. Moreover, the protective efficacy of live immersion treatment in a non-excited immune state without the use of an adjuvant combined with water temperature adjustment was investigated for the first time at 17 °C. Further studies should be targeted to explore the host-associated immune factors responsible for the protective effect and acquired resistance in olive flounder after live VHSV immersion treatment.
病毒性出血性败血症 (VHS) 给韩国的橄榄石斑鱼养殖业造成了严重的经济损失。水温被认为是 VHS 病爆发的关键因素。在这里，我们评估了在不同水温下通过 VHSV 浸泡处理来抵抗 VHSV 的潜在效果，在三种不同水温（10°C、17°C 和 20°C）下，比较了福尔马林灭活 VHSV 浸泡处理和活体 VHSV 浸泡处理获得的抗性。在 10°C 时，活体 VHSV 浸泡组的累积死亡率约为 80%，而福尔马林灭活 VHSV 处理组的累积死亡率为 30%。4 周后，在 17°C 和 20°C 幸存的橄榄石斑鱼在 10°C 时用 VHSV 进行挑战，随后在宿主易感水温下爆发 VHS。对于在 17°C 预处理的鱼，在 10°C 时用活体 VHSV 浸泡组和福尔马林灭活 VHSV 浸泡组进行挑战后的存活率分别为 80%和 30%。然而，在 20°C 预处理的鱼在 10°C 时用活体 VHSV 浸泡组和福尔马林灭活 VHSV 浸泡组进行挑战后的存活率分别为 75%和 20%。我们的结果表明，在非易感水温下使用活体 VHSV 浸泡具有保护橄榄石斑鱼免受 VHSV 感染的潜力。此外，首次在 17°C 下研究了在非兴奋免疫状态下不使用佐剂结合水温调节进行活体浸泡处理的保护效果。应进一步研究探索与宿主相关的免疫因素，这些因素负责在活体 VHSV 浸泡处理后橄榄石斑鱼获得保护作用和抗性。
