Identifying the toxins in hornet (Vespa basalis) venom that induce rat pain responses.

The black-bellied hornet Vespa basalis is responsible for the large quantity of accidents and severe wasp envenomation in China. This study aims to identify the rat pain responses induced by experimental V. basalis sting and related-components in the venom. It was observed that unilateral intraplantar injection of crude V. basalis venom could induce several kinds of pain related behaviors in a dose-dependent manner including spontaneous pain, unilateral thermal and unilateral mechanical hypersensitivity at different time courses. Fourteen main fractions were separated from the crude venom of V. basalis using high performance liquid chromatography, among them, five components (1, 3, 4, 9 and 12) could absolutely mimic the crude venom-induced pain behaviors. According to the molecular mass and N-terminal sequence, the component 3 and 4 were identified as Mastoparan B and HP-1 respectively, the component 9 was speculated as a novel variant of HP-1/2. In addition, the other two sub-components (1-1 and 1-2) purified from component 1 cannot be determined. The results offered the key information about six active polypeptides from V. basalis contributing to pain responses, which might provide a basis for exploring mechanisms of wasp sting injury.