RESUMO
Sterile immunity can be provided against the pre-erythrocytic stages of malaria by IFN-gamma-secreting CD8(+) T cells that recognize parasite-infected hepatocytes. In this study, we have investigated the use of attenuated fowlpox virus (FPV) strains as recombinant vaccine vectors for eliciting CD8(+) T cells against Plasmodium berghei. The gene encoding the P. berghei circumsporozoite (PbCS) protein was inserted into an FPV vaccine strain licensed for use in chickens, Webster's FPV, and the novel FPV vaccine strain FP9 by homologous recombination. The novel FP9 strain proved more potent as a vaccine for eliciting CD8(+) T cell responses against the PbCS Ag. Sequential immunization with rFP9 and recombinant modified vaccinia virus Anakara (MVA) encoding the PbCS protein, administered by clinically acceptable routes, elicited potent CD8(+) T cell responses against the PbCS protein. This immunization regimen elicited substantial protection against a stringent liver-stage challenge with P. berghei and was more immunogenic and protective than DNA/MVA prime/boost immunization. However, further improvement was not achieved by sequential (triple) immunization with a DNA vaccine, FP9, and MVA.
Assuntos
Adjuvantes Imunológicos/administração & dosagem , Linfócitos T CD8-Positivos/imunologia , Vírus da Varíola das Aves Domésticas/imunologia , Esquemas de Imunização , Imunização Secundária , Vacinas Antimaláricas/administração & dosagem , Malária/imunologia , Plasmodium berghei/imunologia , Adjuvantes Imunológicos/sangue , Adjuvantes Imunológicos/genética , Animais , Linfócitos T CD8-Positivos/parasitologia , Linfócitos T CD8-Positivos/virologia , Vírus da Varíola das Aves Domésticas/genética , Vetores Genéticos , Imunização Secundária/métodos , Fígado/citologia , Fígado/imunologia , Malária/sangue , Malária/prevenção & controle , Vacinas Antimaláricas/sangue , Vacinas Antimaláricas/genética , Vacinas Antimaláricas/imunologia , Camundongos , Plasmodium berghei/crescimento & desenvolvimento , Baço/citologia , Baço/imunologia , Esporozoítos/imunologia , Vacinas Atenuadas/administração & dosagem , Vacinas Atenuadas/sangue , Vacinas Atenuadas/genética , Vacinas Atenuadas/imunologia , Vacinas Combinadas/administração & dosagem , Vacinas Combinadas/imunologia , Vacinas de DNA/administração & dosagem , Vacinas de DNA/sangue , Vacinas de DNA/imunologiaRESUMO
The development of in vitro culture systems for the vertebrate stages of Plasmodium led to major advancements in malaria research. Here we review both improvements made in these techniques and the recent achievement of the in vitro growth of mosquito stages from ookinete to infective sporozoite.
Assuntos
Técnicas de Cultura de Células/métodos , Parasitologia/métodos , Plasmodium/crescimento & desenvolvimento , Vertebrados/parasitologia , Animais , Culicidae/parasitologia , Meios de Cultura , Eritrócitos/parasitologia , Humanos , Insetos Vetores/parasitologia , Estágios do Ciclo de Vida , Reprodução Assexuada , Esporozoítos/crescimento & desenvolvimentoRESUMO
We report the first in vitro and genetic confirmation of Malarone (GlaxoSmithKline; atovaquone and proguanil hydrochloride) resistance in Plasmodium falciparum acquired in Africa. On presenting with malaria two weeks after returning from a 4-week visit to Lagos, Nigeria without prophylaxis, a male patient was given a standard 3-day treatment course of Malarone. Twenty-eight days later the parasitaemia recrudesced. Parasites were cultured from the blood and the isolate (NGATV01) was shown to be resistant to atovaquone and the antifolate pyrimethamine. The cytochrome b gene of isolate NGATV01 showed a single mutation, Tyr268Asn which has not been seen previously.