Suitability of a recombinant Staphylococcus aureus enterotoxin C bovine variant for immunodiagnostics and therapeutic vaccine development.

Recombinant bovine variant of staphylococcal enterotoxin C (SECbovine), produced as a NH2-terminal histidine hexamer fusion protein (His6-tagged SECbovine), expressed at high levels (25%) in Escherichia coli and affinity purified to homogeneity (99.9%), was tested for its diagnostic and therapeutic potentials. His6-tagged SECbovine is antigenically authentic to native SECbovine across host species, as confirmed by antibody-based capture detection assays using human, mouse, rabbit and chicken hyperimmune sera. His6-tagged SECbovine showed significant T-cell stimulation activity in vitro. His6-tagged SECbovine was immunogenic for IgG in mice (intragastric and intravenous routes) and rabbits (intramuscular and subcutaneous routes), dispensing immunoadjuvant coadministration. The formation of neutralizing antibodies reduced the severity of intoxication symptoms in immunized rabbits. Purified anti-recombinant SECbovine rabbit polyclonal IgG neutralized the pyrexic and diarrhoeagenic effects of native SEC/SED and recombinant SEC, tested by the kitten and rabbit bioassays, respectively.