ABSTRACT
Our goal is to develop a vaccine that sustainably prevents Plasmodium falciparum (Pf) malaria in ≥80% of recipients. Pf sporozoites (PfSPZ) administered by mosquito bites are the only immunogens shown to induce such protection in humans. Such protection is thought to be mediated by CD8(+) T cells in the liver that secrete interferon-γ (IFN-γ). We report that purified irradiated PfSPZ administered to 80 volunteers by needle inoculation in the skin was safe, but suboptimally immunogenic and protective. Animal studies demonstrated that intravenous immunization was critical for inducing a high frequency of PfSPZ-specific CD8(+), IFN-γ-producing T cells in the liver (nonhuman primates, mice) and conferring protection (mice). Our results suggest that intravenous administration of this vaccine will lead to the prevention of infection with Pf malaria.
Subject(s)
CD8-Positive T-Lymphocytes/immunology , Liver/immunology , Malaria Vaccines/immunology , Malaria, Falciparum/prevention & control , Plasmodium falciparum/immunology , Sporozoites/immunology , Adolescent , Adult , Animals , Antibodies, Protozoan/blood , Antibodies, Protozoan/immunology , Antigens, Protozoan/immunology , Humans , Injections, Intravenous , Injections, Subcutaneous , Interferon-gamma/biosynthesis , Interferon-gamma/immunology , Macaca mulatta , Malaria Vaccines/administration & dosage , Malaria Vaccines/adverse effects , Mice , Middle Aged , Rabbits , Vaccines, Attenuated/administration & dosage , Vaccines, Attenuated/adverse effects , Vaccines, Attenuated/immunology , Young AdultABSTRACT
We have developed a system for stable germline transformation in the silkworm Bombyx mori L. using piggyBac, a transposon discovered in the lepidopteran Trichoplusia ni. The transformation constructs consist of the piggyBac inverted terminal repeats flanking a fusion of the B. mori cytoplasmic actin gene BmA3 promoter and the green fluorescent protein (GFP). A nonautonomous helper plasmid encodes the piggyBac transposase. The reporter gene construct was coinjected into preblastoderm eggs of two strains of B. mori. Approximately 2% of the individuals in the G1 broods expressed GFP. DNA analyses of GFP-positive G1 silkworms revealed that multiple independent insertions occurred frequently. The transgene was stably transferred to the next generation through normal Mendelian inheritance. The presence of the inverted terminal repeats of piggyBac and the characteristic TTAA sequence at the borders of all the analyzed inserts confirmed that transformation resulted from precise transposition events. This efficient method of stable gene transfer in a lepidopteran insect opens the way for promising basic research and biotechnological applications.
