Optimization of PCR-based assay for detection of tilapia lake virus in Tanzania

Masters Thesis

Tilapia Lake Virus disease (TiLVD) is an emerging disease that affects the aquaculture industry world-wide. The disease is caused by the orthomyxo-like virus with 10 segments on its genome called Tilapia Lake Virus (TiLV). The TiLVD causes massive tilapia mortalities, and hence leads to economic loss and food insecurity. The detection of TiLV genome in Lake Victoria from previous study has prompted the need for investigation of TiLV in the region. To understand the infection status of TiLV in Tanzania, the polymerase chain reaction (PCR) - based assay was optimized in the laboratory, followed by a cross-sectional study in Mwanza, Morogoro, Pwani and Iringa regions to unravel the situation of TiLV infection in different aquaculture production systems. The internal fish organs including spleens, kidney, eggs and whole fingerling/fry were analyzed by the optimized PCR-based assay targeting segment-2 of the virus and nucleotide sequencing. The findings from the field study indicated zero prevalence of TiLV genome (N = 120). When the optimized method applied to test the samples from Lake Victoria that used in previous studies, the TiLV genome was detected. Despite the fact that, TiLV genome was not detected in the examined samples, the optimized PCR-based assay and sequencing protocols for TiLV have the potential of being used in surveillance and identification of TiLV. More studies are required to further optimize the protocols and investigate the prevalence and risk factors associated with the occurrence of TiLVD and associated infections.

TRAHESA project