Fig. 4
Purification of the HPV His6-E6 proteins under native conditions. The optimized protocol for HPV16 His6-E6 protein production was applied to the E6 protein from the different HPVs. a Coomassie blue staining of representative SDS-PAGE of purified E6 protein from HPV11 (lane 2), HPV16 (lane 3) and HPV18 (lane 4) after one chromatographic step. Lane 1, HPV16 His6-E6 protein produced under denaturing conditions, as control. b Representative immunoblot of the HPV18 and HPV11 His6-E6 proteins purified under native conditions before (a) and after (b) dialysis and concentration. C+ , concentrated HPV16 His6-E6 protein, as control. c Coomassie blue staining of representative SDS-PAGE of HPV16 His6-E6 protein stored for more than 2 years at 4 °C (lane 1) and −20 °C (lane 2)