Abstract:

Hygromycin B phosphotransferase gene (hpt) has been widely used in the process of gene construction when agricultural plants are modified by biotechnology. Hpt protein as an introduced “new” protein was obtained from sources with no prior history of causing allergy, thus its safety assessment was mainly focused on comparison of amino acid sequences, in vitro digestibility and animal model according to the IFBC-ILSI. Individual sequence analysis with known amino acid sequences, reported as allergens, showed that no eight continuous amino acids are observed; Hpt protein is unstable to heat for its complete decomposition at 80 ℃ for 10 min. It is also digested within the first 20 min by simulated gastric fluid treatment as observed by SDS-PAGE and Western blotting. BN rats were used to establish allergenicity model. The levels of IgG, IgE and histamine were tested by ELISA. The results showed that the Hpt protein has significant difference with the positive (p ＜ 0.05), but no difference with the negative. In conclusion, Hpt protein has low probability to induce allergenicity. The results can provide basic data for evaluating the safety of genetically modified plants which use hpt as marker gene.

Key words: hygromycin B phosphotransferase gene, safety assessment, in vitro digestibility, animal model, allergenicity