A) Scheme of DNA constructs and the expected products used for immunisations. B) Western blot profile of expression and secretion from transfected HEK293T cells (E, cellular extracts; S, culture supernatants) of sE-SV5, DI/DII-SV5 and DIII-SV5 constructs from DENV3 and DENV4; anti-actin was used as loading control. C) ELISA antibody titres of pooled sera from mice immunised with the indicated constructs determined on plates coated with homologous sE, DIII or DI/DII antigens from DENV3 (left panel) and DENV4 (right panel) as indicated (in each case, n = 4. Comparisons of anti-sE reactivity against sE and DI/DII antigens (t = 1.172 df = 6 for DENV3, t = 1.541 df = 6 for DENV4), and against sE and DIII antigens (t = 8.160 df = 6 for DENV3, t = 28.22 df = 6 for DENV4) are shown. *, indicates antibody titre below pre-immune control.