Persistence of Tilapia tilapinevirus in fish rearing and environmental water and its ability to infect cell line.

Abstract

Tilapia tilapinevirus, or Tilapia Lake Virus (TiLV), is a RNA virus associated with mass morbidity and mortality in tilapia, leading to severe economic losses for global tilapia aquaculture. In this study, we investigated the persistence of TiLV in water by spiking sterile distilled water (SDW), freshwater collected from rearing fish tanks (FW) and natural pond water (PW) at 27°C as a representative of environmental water conditions with 0.6ml of stock virus (3.18×107 viral copies/ml of water). The water samples were filtered through an electronegative charge membrane and quantified using reverse transcriptase quantitative PCR at 0, 3, 5, 7, 10 and 14days post-inoculation. The results revealed that TiLV RNA in SDW was reduced by 1.34 log10 in 14days. A similar approximately 4 log10 removal of the virus in FW and PW was observed at 3 and 7days, respectively. Moreover, the infectivity of TiLV was further studied; the virus lost its infectivity in E-11 cells after 1day in SDW, FW and PW water samples, even though the virus was spiked 10 more times than in the viral persistence study. Taken together, the results could be applied to improving biosecurity practices in tilapia farms by disinfecting or resting reservoir water for at least three to five days prior to stocking tilapia, to limit the spread of TiLV.