Bài báo khoa học

This study was conducted to evaluate the susceptibility of tilapia in the nursery stage to tilapia lake virus, to assess the influence of temperature and salinity on pathogenicity, and to determine kinetics of virus shedding. After 17 dpi, the cumulative mortality of juvenli, fry and fingerlings reached the maximum, after 21 dpi, the average cumulative mortality of fry, fry, and fingerlings, respectively, was 100%, 96.5% and 74%. At the temperature conditions of 220C, 250C, 270C, 300C, 320C and salinity of 3 ppt and 5ppt, the survival rate of fingerlings after 30 dpi at the temperature threshold of 220C and 320C decreased by 2.2-2.3 times compared with the temperature thresholds of 250C, 270C and 300C, temperature stress has reduced the resistance able of fish to pathogens. The shedding kinetics of strain TiLV ND38 from infected fish into the aquatic environment was determined in 30 days, by RT-qPCR, viral ARN was detected during 3-16 dpi; the highest viral concentrations were detected between 6-8 dpi with log10 value of 4.35, 5.15 and 4.8 (equipvalent to 2,26 x 104, 1,41 x 106, 6,28 x 105 ARN copies/litter of water), respectively. From 17 dpi, the virus load gradually decreased and was below the detection threshold. The obtained results are initially the basis for determining the epidemiology of the disease, from which to continue to research and propose appropriate prevention solutions.