Detection of Tilapia Lake Virus (TiLV) in Healthy Fish from the Pre-Existing Disease Environment Using Different RT-PCR Methods

We investigated the presence of TiLV in different fish species from the water reservoir that TiLV was previously reported. The virus was detected in healthy wild tilapia (Oreochromis niloticus) and farmed barramundi (Lates calcarifer) that shared water supply. Detection of TiLV was performed using three RT-PCR assays. Semi-nested RT-PCR detected 9 positives, while the nested and one-step RT-PCR produced 7 and 4 positives, respectively. This study shows evidence that TiLV found in these two fish species is associated with the virus circulating in close proximity environment, nevertheless, it is deficient to indicate disease infection in these asymptomatic fish.