Use of the chemical inhibitor of cysteine proteases E64 significantly reduced lesion size in MGAS5005Δ<i>srv</i> infected animals.

<p>Representative images of lesions formed in mice at 1, 3 and 8 days following subcutaneous infection with ∼2×10⁸ CFU of MGAS5005Δ<i>srv</i>. (A) The infecting dose of MGAS5005Δ<i>srv</i> was suspended in 333 uM E64 (0.1 ml), and lesion development (mm²) was monitored over 8 days (<i>n</i> = 10 mice). A significant reduction in lesion formation was observed when E64 was inoculated with the infecting dose of MGAS5005Δ<i>srv</i> compared to inoculation with MGAS5005Δ<i>srv</i> alone (<i>p</i><0.05). (B) Following inoculation of animals with E64+MGAS5005Δ<i>srv</i> as before, an additional inoculation of 333 µM E64 (0.1 mL) was injected directly into the abscess each day following infection (<i>n</i> = 10). A significant reduction in lesion size was observed with E64 treated animals forming lesions roughly equivalent in size to untreated MGAS5005 infected animals.