Application of a Chimeric Protein Construct having Enterotoxin B and Toxic Shock Syndrome Toxin Domains of S. aureus in Immunodiagnostics

Staphylococcal enterotoxin B (SEB) and toxic shock syndrome toxin-1 are the super antigens responsible for diseases such as staphylococcal food poisoning and toxic shock syndrome. At low serum concentrations, SEB can trigger toxic shock, profound hypotension and multi organ failure and hence is recognized as biowarfare molecule. In this study, a multidomain fusion protein (r-TE) was generated with specificity for SEB and toxic shock syndrome toxin (Tsst-1). The fusion gene comprising the conserved regions of seb and the tsst genes was codon-optimized for expression in Escherichia coli and encoded a 26 kDa recombinant multidomain chimeric protein (r-TE). Hyperimmune antiserum raised against r-TE specifically reacted with SEB (~28 kDa) and Tsst-1 (~22 kDa) components during Western blot analysis and by plate ELISA in confirmed toxin producing strains of S. aureus. The antigenicity of the SEB component of the r-TE protein was also confirmed using TECRA kit. The described procedure of creating a single protein molecule carrying components of two different toxins whilst still retaining the original antigenic determinants of individual toxins proved highly advantageous in the development of rapid, reliable and cost effective immunoassays and may also have the potential to serve as candidate molecule for vaccine studies.