FIG. 3.

Poly(C-G), but not poly(I-C) or poly(C), induces the antiviral state. Shrimp (1 to 2 g, n = 38 to 42) were injected with 8 μg (a) or 7 μg (b) of synthetic dsRNA analogues as indicated and infected 72 h later with WSSV. All RNA analogues were purchased from Sigma-Aldrich, reconstituted in 400 mM NaCl-10 mM Tris-Cl (pH 7.4), and annealed and quantified as described in Materials and Methods. dsRNA for the duck υ (7 μg) was included in the experiment on panel b for comparison. The chi-square statistic was used to assess the significance of the observed antiviral protection relative to positive controls: (a) poly CG (χ² = 16.92 [P < 0.001]) and (b) duck Igυ dsRNA (χ² = 32.17 [P < 0.001]) and poly(C-G) (χ² = 35.05 [P < 0.001]).