Identification of fusion-GEM complexes
To prepare GEM, L. lactis was boiled with TCA. In this process, the bacteria were killed, and DNA and proteins were degraded. GEM maintained the original shape and size of the bacterial skeleton, with a smooth surface, and showed good binding with fusion proteins (Fig. 2A). The cell culture supernatants (ZI-△-PA, ZI-JE-△-PA and ZI-GP-△-PA protein) were selected for binding with GEM and verified by TEM. The results showed obvious floccules on the surface of GEM (Fig. 2B).
Furthermore, fusion-GEM complexes with successful binding (ZI-△-PA-GEM, ZI-JE-△-PA-GEM and ZI-GP-△-PA-GEM) were selected for further investigation to verify the ZIKV-E protein in the binding products. The samples showed bright green fluorescence as determined by IFA (Fig. 2C), and the target protein was detected by WB analysis (Fig. 2D). These results indicated that prM-E-△-PA3 with an ST-TM region deletion could successfully bind GEM.