Figure 4
Pretreatment of mice with serine protease inhibitors results in less severe weight loss after influenza infection. C57BL/6J mice were pre-treated with protease inhibitors and then infected intra-nasally with 2 × 103 FFU of the H1N1 virus each. Body weight was measured at each day p.i. and is presented as percent of original weight before infection (day 0). Pretreatment of C57Bl/6J mice with AEBSF (A; 125 μg/25 μl/mouse) or with the serine protease inhibitor cocktail (C; 125 μg AEBSF, 400 μg p AB/25 μl/mouse) prior to infection with H1N1 (n = 8 each group) resulted in a significant reduction (P < 0.05) in the weight loss and faster recovery of treated mice compared to untreated infected controls (n = 10). On the other hand, pretreatment of C57Bl/6J mice with 400 μg p AB/25 μl/mouse (B; n = 8) resulted in a non significant reduction in the weight loss of treated mice compared to untreated infected controls (n = 10). AEBSF showed the lowest effect in terms of reduction of weight loss after pre-treatment of C57Bl/6J mice (n = 6) infected with H7N7 virus (D). Treatment of C57Bl/6J mice with the p AB (E; n = 6) or with the serine protease inhibitor cocktail (F; n = 6) at the doses described above prior to infection with the H7N7 virus resulted in a significantly (P < 0.05) reduced weight loss early after infection and a faster recovery of treated mice compared to untreated control groups (n = 6). The effect of weight loss reduction in mice treated with the inhibitor cocktail was even more pronounced after infection with the H7N7 virus compared to infection with the H1N1 virus. Each data point represents the mean percent body weight value of the tested mice +/- 1 SD.