Affinity-purified dengue-2 virus envelope glycoprotein induces neutralizing antibodies and protective immunity in mice.

We constructed a recombinant baculovirus which produces a dengue (DEN)-2 virus envelope (E) protein containing a six-histidine (H6) tag in place of the last 100 amino acids at its C-terminus. The recombinant protein was purified from the supernatant of baculovirus-infected Spodoptera frugiperda insect cell cultures to apparent homogeneity by cation-chelation chromatography (TALON) in which the H6-tagged E-protein was eluted under non-denaturing conditions with 100 mM imidazole at pH 8.0. Mice vaccinated with the purified E mixed with aluminium hydroxide adjuvant showed an immune response of IgM and IgG1, IgG2a and IgG2b isotypes, and neutralizing antibodies, similar to that following immunization with purified inactivated DEN-2 virus. Moreover, mice that received the purified recombinant protein were significantly protected against 200 50% lethal dose of DEN-2 virus. This combination of affinity purified H6-tagged protein and adsorption onto a cationic carrier seems promising for the production of immunogenic particulate proteins, especially DEN protein for the four serotypes, and the development of a new generation of vaccines.