Conjugation of DnaK, OmpA and Tul4 Proteins of F. tularensis SchuS4 to TMV.
Purified OmpA, DnaK and Tul4 proteins were combined with purified TMV and incubated with EDC and NHS for 0, 30 min, 1, or 2 hours as described in Methods section. Two μg of TMV or recombinant proteins DnaK, OmpA, Tul4 or 4 μg of the TMV-protein mixtures were resolved on an 8–16% SDS-PAGE gel to observe conjugation products indicated by changes in the molecular masses of the starting materials. (A) Conjugation of DnaK, OmpA and Tul4 to a single TMV virion to generate TMV-monoconjugate vaccine. The progress of conjugation process was observed over a period of time: Lane M = Precision Plus Dual Color standard (BioRad) Marker; Lane 1 = TMV-protein mix, 0 min; Lane 2 = TMV-protein mix, 30 min; Lane 3 = TMV-protein mix,1 hour; Lane 4 = TMV-protein mix, 2 hours. (B, C, D) Kinetics of DnaK, OmpA and Tul4 TMV-protein conjugations over a two hour incubation period to generate TMV-protein conjugates. The individual TMV-protein conjugates were then admixed to generate TMV-multiconjugate vaccine. Lane M = Precision Plus Dual Color standard (BioRad) Marker; Lane 1 = TMV; Lane 2 = Recombinant protein; Lane 3 = TMV-protein mix, 0 hour; Lane 4 = TMV-protein mix, 1 hour; Lane 5 = TMV-protein mix, 2 hours. In all cases, 2 hour time points were used for scale-up and vaccine preparation. Solid arrows indicate TMV-protein conjugate(s), dashed arrows indicate free TMV or free proteins.