Dengue type-2 virus envelope protein made using recombinant baculovirus protects mice against virus challenge.

The gene coding for the envelope (E) glycoprotein of dengue-2 virus was cloned into baculovirus (Autographa californica nuclear polyhedrosis virus). The recombinant virus contained the entire E protein gene, preceded by 38 nucleotides from the end of the prematrix glycoprotein gene and followed by the first 83 nucleotides of nonstructural protein 1. When expressed in Spodoptera frugiperda (Sf9) cells, approximately 1 mg of recombinant E antigen was made per 10(9) cells. This antigen reacted with polyclonal, anti-dengue type-2 antibody and a dengue type-2-specific, neutralizing monoclonal antibody. BALB/c mice immunized with the recombinant antigen produced only non-neutralizing antibody against dengue-2 virus, but were partially protected against morbidity and mortality after intracranial challenge with virulent dengue-2 virus.