Detection of Tilapia lake virus (TiLV) using semi-nested RT-PCR method in farmed Tilapia ( Oreochromis niloticus) from ponds East Java, Indonesia

Tilapia lake virus disease is an emerging viral disease causing mortality up to 90% worldwide of aquaculture production. It has been recorded as a virus attacting wild and cultured tilapias in Asia, Africa, and Latin America. There is the urgent need for rapid Diagnostic techniques for viral diseases to identify infected tilapia to control the outspread in individual farms. This study aims to identify the presence of TiLV with the semi-nested Reverse Transcriptase-Polymerase Chain Reaction method allowing the rapid detection of TiLV in fish organs. A total of 4 samples of tilapia were isolated from different locations and then used a silica extraction kit to obtain RNA from the TiLV virus. Afterwards amplification step was carried out by semi-nested RT-PCR test. The primers used in PCR target the 250-bp fragment in the electrophoresis. The results showed that the 250 bp amplicon of TiLV RNA was detected at 1/4 tested Tilapia. PCR clearly identified infective TiLV viral RNA in tilapia that produced a cytopathic effect with protein similarity (weak homology) in the conserved Polymerase Sub Unit PB1 Influenza-C and the genome of Orthomyxoviruses causing brain, nervous system and liver damage in fish and may have applications as rapid species-specific virulence test.