Immunogenicity and protective efficacy of a recombinant fusion protein containing the domain III of the dengue 1 envelope protein in non-human primates.

Recombinant fusion proteins containing the aa 286-426 of the dengue envelope protein fused to P64k protein from Neisseria meningitidis have been previously reported. Particularly, the immunogenicity and protective capacity of the dengue 2 recombinant protein was demonstrated in Macaca fascicularis monkeys. Here we evaluate the recombinant fusion protein containing the domain III of the dengue 1 envelope protein (PD10) in non-human primates (M. fascicularis and rhesus monkeys) and compare the effect of aluminum hydroxide and Freund adjuvant on the immunity induced. The PD10 protein emulsified in Freund adjuvant was highly immunogenic in M. fascicularis and rhesus monkeys. Following dengue 1 virus challenge, animals immunized with PD10 in Freund adjuvant were protected from viremia. However, monkeys receiving PD10 in aluminum hydroxide developed a poor antibody response and were not protected from viral challenge. These preliminary experiments are encouraging. Other formulations or vaccine schedules are being studied in an attempt to find regimens that enhance immunological protection.