Fig. 1

GCRV blocks the amplification of SVCV in zebrafish. A Survival rates of zebrafish infected with different viruses in combination with SVCV. Adult zebrafish were injected with SVCV [5 × 10⁹ 50% tissue culture infective dose (TCID₅₀)/mL, 5 μL/individual] and GCRV/GCRV-II/CaHV (5 × 10⁷ TCID₅₀/mL, 5 μlLindividual). Mortality recorded over eight days (number of individuals = 15). B Survival rates of zebrafish decreased with combined injection of GCRV and SVCV. Adult zebrafish were injected with PBS only (10 μL/individual), SVCV (5 × 10⁹ TCID₅₀/mL, 5 μL/individual and 5 μL PBS to make up 10 μL/individual), GCRV (5 × 10⁷ TCID₅₀/mL, 5 μL/individual and 5 μL PBS to make up 10 μL/individual), or SVCV&GCRV [(5 × 10⁹ TCID₅₀/mL, 5 μL/individual) for SVCV and (5 × 10⁷ TCID₅₀/mL, 5 μL/individual) for GCRV]. Mortality recorded over eight days (number of individuals = 35). C Microscopy of hematoxylin and eosin (H&E)-stained heart, liver, and spleen sections from male and female zebrafish treated with SVCV (5 × 10⁹ TCID₅₀/mL, 5 μL/individual) or SVCV&GCRV [(5 × 10⁹ TCID₅₀/mL, 5 μL/individual) for SVCV and (5 × 10⁷ TCID₅₀/mL, 5 μL/individual) for GCRV] for 72 h. Histological changes were examined by optical light microscopy for histological changes at ×40 magnification. The location of the pathological area was indicated by white arrows. D Tissue immunofluorescence (IF) of liver, spleen, and heart tissue sections of SVCV infected zebrafish. The green fluorescence of tissue slices was observed with a confocal microscope under a 20× immersion objective (SP8; Leica) and indicates proliferation of SVCV. Scale bar, 10 μm. E Immunoblotting (IB) detection of virus abundance in the tissues of zebrafish in Null, SVCV, and SVCV&GCRV treatment groups. Scale bar, 20 μm. F Transcript levels of SVCV genes in zebrafish tissues of indicated treatment groups. The β-actin gene was used as an internal control and the relative expressions of SVCV genes were represented as fold induction relative to the expression level in control cells (set to 1). Data were expressed as mean ± standard error of the mean (SEM), n = 3. Statistical analysis was performed by the Student's t-test. Asterisks indicate significant differences from control (^∗P < 0.05).