ABSTRACT
Previously, we reported the ability of the chimeric protein DIIIC-2 (domain III of the dengue envelope protein fused to the capsid protein of dengue-2 virus), to induce immunity and protection in mice, when it is highly aggregated with a non-defined oligodeoxynucleotide (ODN) and adjuvanted in alum. In this work, three different defined ODNs were studied as aggregating agents. Our results suggest that the nature of the ODN influences the capacity of protein DIIIC-2 to activate cell-mediated immunity in mice. Consequently, the ODN 39M was selected to perform further experiments in mice and nonhuman primates. Mice receiving the preparation 39M-DIIIC-2 were solidly protected against dengue virus (DENV) challenge. Moreover, monkeys immunized with the same preparation developed neutralizing antibodies, as measured by four different neutralization tests varying the virus strains and the cell lines used. Two of the immunized monkeys were completely protected against challenge, whereas the third animal had a single day of low-titer viremia. This is the first work describing the induction of short-term protection in monkeys by a formulation that is suitable for human use combining a recombinant protein from DENV with alum.
Subject(s)
Antibodies, Viral/biosynthesis , Capsid Proteins/immunology , Dengue Virus/immunology , Dengue/prevention & control , Recombinant Fusion Proteins/immunology , Viral Envelope Proteins/immunology , Adjuvants, Immunologic/administration & dosage , Alum Compounds/administration & dosage , Animals , Antibodies, Neutralizing/biosynthesis , Antibodies, Neutralizing/blood , Antibodies, Viral/blood , Capsid Proteins/genetics , Chlorocebus aethiops , Dengue/immunology , Dengue/virology , Dengue Vaccines/administration & dosage , Dengue Vaccines/genetics , Dengue Vaccines/immunology , Dengue Virus/chemistry , Female , Flocculation , Gene Expression , Immunity, Cellular/drug effects , Immunity, Humoral/drug effects , Immunization , Mice , Mice, Inbred BALB C , Neutralization Tests , Oligodeoxyribonucleotides/chemistry , Oligodeoxyribonucleotides/immunology , Protein Binding , Recombinant Fusion Proteins/administration & dosage , Recombinant Fusion Proteins/genetics , Viral Envelope Proteins/geneticsABSTRACT
OBJECTIVE: This study evaluated the use of a non-human primate, the olive baboon (Papio anubis), as a model of dengue infection. Olive baboons closely resemble humans genetically and physiologically and have been used extensively for assessing novel vaccine formulations. METHODS: Two doses of dengue virus type 2 (DENV-2) were tested in baboons: 10(3) and 10(4) pfu. Similarly, African green monkeys received the same quantity of virus and acted as positive controls. RESULTS: Following exposure, high levels of viremia were detected in both animal species. There was a trend to detect more days of viremia and more homogeneous viral titers in animals receiving the low viral dose. In addition, baboons infected with the virus generally exhibited positive virus isolation 1 day later than African green monkeys. Humoral responses consisting of antiviral and neutralizing antibodies were detected in all animals after infection. CONCLUSIONS: We conclude that baboons provide an alternative non-human primate species for experimental DENV-2 infection and we recommend their use for further tests of vaccines, administering the lowest dose assayed: 10(3) pfu.
