Characterization and evaluation of the enzymatic activity of tetanus toxin submitted to gamma radiation by Cobalt 60

Abstract

Tetanus is a neurological disease which blocks the inhibitory neurotransmitters liberation. Also treatment does not cure the disease, and its main form of prevention is through vaccination. The vaccine is produced by the inactivation of tetanic toxin (TeNT) with formaldehyde, which may cause side effects. An alternative way is the use of ionizing radiation for inactivation of the toxin and also to improve the potential immunogenic response and to reduce the pos-vaccination side effects. Therefore, the aim of this study was to characterize the TeNT structure after different doses of ionizing radiation of Cobalt 60, and also to assess the enzymatic activity after the radiation. SDS PAGE and MALDI-TOF analysis revealed gradual modification on the TeNT structure according to doses increase. Also, fragmentation and possible aggregations of the protein fragments were observed in higher doses. In the analysis of peptide preservation by enzymatic digestion and mass spectrometry, there was a slight modification in the recognition up to the dose of 4 kGy at subsequent doses, recognition was minimal. The analysis of the enzymatic activity by fluorescence showed a 35 % attenuation in the activity even at higher doses. In the antigenic evaluation performed by ELISA and Western Blot, anti-TeNT antibodies were detected against the irradiated toxins at the different doses, with a gradual decrease as the dose increased, but remaining at satisfactory levels, indicating the possibility of possible use as an immunogen, however, studies of enzymatic activity on higher should be further analyzed.