C. Delenda et al., ANALYSIS OF C-TERMINALLY TRUNCATED DENGUE-2 AND DENGUE-3 VIRUS ENVELOPE GLYCOPROTEINS - PROCESSING IN INSECT CELLS AND IMMUNOGENIC PROPERTIES IN MICE, Journal of General Virology, 75, 1994, pp. 1569-1578
We constructed two recombinant Autographa californica nuclear polyhedr
osis baculoviruses. Spodoptera frugiperda (Sf9) cells containing these
constructs produce carboxy-terminally truncated envelope E proteins r
epresenting dengue (DEN) virus serotypes 2 and 3. The two recombinant
proteins contained their homologous signal sequences at the N terminus
and were truncated by 71 and 74 amino acids at the C terminus, respec
tively, This allowed the translocation of the recombinant proteins to
the endoplasmic reticulum followed by glycosylation processing and sec
retion into the extracellular medium. An additional unglycosylated for
m which was not secreted was detected inside the infected Sf9 cells. S
era from Swiss mice immunized with the infected Sf9 cell lysates gave
a DEN cross-reactive response in ELISA and substantial amounts of neut
ralizing antibodies to the homologous virus. Similar antibody titres w
ere obtained when the two recombinant proteins were inoculated concomi
tantly. BALB/c mice were vaccinated with three doses of the recombinan
t E proteins, taken as monovalent or bivalent immunogens, and challeng
ed with mouse-adapted DEN-2 virus. DEN-2 E protein induced a good prot
ection (90%) against lethal encephalitis and recombinant DEN-3 E prote
in gave a substantial cross-protection (54%). Eighty-two percent of th
e mice immunized with a mixture of both recombinant E proteins survive
d the DEN-2 virus challenge.