Figure 1. Acute systemic responses of naive C57BL/6 and BALB/c mice to increasing doses of BV.

(A) Experimental outline. (B and C) Schematic showing sites of s.c. injection of up to 4 or 5 doses of BV (or PBS) in (B) C57BL/6 and (C) BALB/c mice. Arrowheads indicate the injection sites in the shaved area(s). Injections were carried out in alphabetical order, depending on the number of injections. In studies of innate responses to BV, C57BL/6 and BALB/c mice received 1–5 doses of BV or PBS (x3) (see D–G below). In experiments in which mice were challenged with high dose BV, C57BL/6 mice always got 4 injections of BV (200 µg each, as shown in B) and BALB/c mice always got 5 injections of BV (200 µg each, as shown in C). Female (D and E) C57BL/6 and (F and G) BALB/c WT mice were treated s.c. with the indicated doses of BV. Mock-treated control mice received 3 injections of PBS. Mice receiving 1–3 injections were treated in the back only (see B and C, arrows a–c); mice injected 4 times received 3 injections in the back and 1 in the belly (see B, arrows a-d); mice injected 5 times received 4 injections in the back and 1 in the belly (see C, arrows a–e). (D and F) Changes in body temperature (Δ Temp [mean ± SEM]) and (E and G) survival (% of live animals) were monitored at the indicated times. P values are versus PBS-treated mice and were calculated by (D and F) Student’s t test or (E and G) Mantel-Cox test. (D – G) Data are pooled from 2 (for groups receiving 4× or 5× 200 µg BV) or 3 (all other groups) independent experiments (n=10–19/group). *, P < 0.05; **, P < 0.01; ***, P < 0.001 versus PBS; numbers in D, E and G are the P values for comparisons to PBS that were not significant (P > 0.05). See also Figures S1 for a similar set of experiments with Russell’s viper venom.