Determination of hyaluronidase activity in Tityus spp. scorpion venoms and its inhibition by Brazilian antivenoms.

Hyaluronidases (HYALs) are enzymes ubiquitously found in venoms from diverse animals and seem to be related to venom spreading. HYAL activity might be important to Tityus spp. envenoming, since anti-Tityus serrulatus HYAL (TsHYAL) rabbit antibodies neutralize T. serrulatus venom (TsV) lethality. The present work aimed to verify and compare HYAL activity of venoms from other Brazilian Tityus spp. (Tityus bahiensis, Tityus stigmurus and Tityus obscurus) and to test whether anti-TsHYAL antibodies and Brazilian horse therapeutic scorpion antivenom (produced by Fundação Ezequiel Dias (FUNED), Butantan and Vital Brazil Institutes) can recognize and inhibit HYAL activity from these venoms. In ELISA assays, anti-TsHYAL and scorpion antivenoms recognized T. serrulatus, T. bahiensis and T. stigmurus venoms, however, they demonstrated weaker reaction with T. obscurus, which was also observed in Western blotting assay. Epitope mapping by SPOT assay revealed different binding patterns for each antivenom. The assay showed a weaker binding of scorpion antivenom produced by FUNED to peptides recognized by anti-TsHYAL antibodies. Anti-TsHYAL antibodies and antivenoms produced by Butantan and Vital Brazil institutes inhibited HYAL activity of all tested venoms in vitro, whereas FUNED antivenom did not show the same property. These results call attention to the importance of hyaluronidase inhibition, that can aid the improvement of antivenom production.