Enhancement of dengue-2 E protein expression by the expression of the precursor membrane protein (prM) of the dengue-3 virus

Abstract

Several attempts to develop dengue recombinant subunit vaccines have failed due to insufficient levels of expression and incorrect folding of the E protein. In order to verify the importance of the precursor membrane protein to the level of E protein expression, we constructed two recombinant plasmids by cloning the full-length sequence of the prM gene from the dengue-2 and dengue-3 virus strains into a plasmid that expresses a truncated version of the E protein of the dengue-2 virus. Next, we evaluated these two constructs for their effect on the levels of E protein expression in vitro. Our results showed that both plasmids provided a correct expression of the E protein as E protein expression was detected in transfected Vero cells as demonstrated by indirect immunofluorescence and immunoblotting. Densitometry analysis of western blots of the cell extracts showed a 67.02% higher expression of E protein in the cells transfected with pCID2EtD3prM, indicating that the prM sequence of the dengue-3 virus may be more effective in assisting with the correct processing of the E protein. The results of this study may be used to increase the in vitro production of the E protein antigen for use in vaccines and for diagnostic purposes. © 2013 de Oliveira MD, et al.