Recombinant TTHc: is frequently used as the carrier protein for conjugate vaccines, in addition to being a component of the DPT vaccine. TT contains very strong T cell epitopes. However, as a toxoided protein, many of the surface lysines are blocked by the toxoiding process. TT is not a uniform product. Each manufacturer has its own specific toxoiding and purification process. Tetanus tends to aggregate with age. Furthermore, TT is not generally affordable in the quantities needed for research and early clinical work. Tetanus toxoid heavy chain fragment C (TTHc) is the C terminal fragment of the toxin. It is devoid of the toxin s enzymatic activity but contains the binding site necessary for uptake of the toxin by neurons. Significantly, the majority of the antibody response to tetanus toxoid is against epitopes contained within TTHc. Fragment C contains the powerful T cell epitopes of tetanus toxin without the toxicity. Fina Biosolutions now offers recombinant TTHc (rTTHc), combining the advantages of the toxoid with the reproducibility of a recombinant protein. FinaBio expresses rTTHc as a properly folded, soluble protein in E. coli cytoplasm.