RESUMO
Intraerythrocytic parasites degrade haemoglobin to make available nutrients for their growth and maturation. Plasmepsins, the aspartic proteases of Plasmodium play a significant role in haemoglobin degradation and are proposed as attractive drug targets. In the present study the gene which encodes plasmepsin in rodent malaria parasite, Plasmodium berghei, was cloned and expressed. The gene was sequenced and expressed in Escherichia coli BL21DE3 and a recombinant plasmepsin of molecular weight 43 kDa was obtained. The sequence obtained was analysed and compared with plasmepsins of other Plasmodium spp. Mice immunized with the recombinant plasmepsin induced a strong humoral immune response. ELISA and IFA performed on the serum of immunized mice showed high antibody titres. Along with this, in vivo study exhibited partial protection against P. berghei infection suggesting role of plasmepsin in malaria control.
Assuntos
Ácido Aspártico Endopeptidases/imunologia , Vacinas Antimaláricas/imunologia , Malária/prevenção & controle , Plasmodium berghei/imunologia , Animais , Anticorpos Antiprotozoários/sangue , Ácido Aspártico Endopeptidases/química , Ácido Aspártico Endopeptidases/genética , Clonagem Molecular , Modelos Animais de Doenças , Ensaio de Imunoadsorção Enzimática , Escherichia coli/genética , Técnica Indireta de Fluorescência para Anticorpo , Expressão Gênica , Vacinas Antimaláricas/administração & dosagem , Vacinas Antimaláricas/genética , Camundongos , Peso Molecular , Plasmodium berghei/genética , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/imunologia , Análise de Sequência de DNA , Vacinas de Subunidades Antigênicas/administração & dosagem , Vacinas de Subunidades Antigênicas/genética , Vacinas de Subunidades Antigênicas/imunologia , Vacinas Sintéticas/administração & dosagem , Vacinas Sintéticas/genética , Vacinas Sintéticas/imunologiaRESUMO
The hunt for an effective vaccine against malaria still continues. Several new target antigens as candidates for vaccine design are being explored and tested for their efficacy. In the present study the sera from mice immunized with 24,000 x g fraction of Plasmodium berghei has been used to identify highly immunogenic blood stage antigens. The protective antibodies present in immune sera were covalently immobilized on CNBr activated sepharose 4B and used for affinity chromatography purification of antigens present in blood stages of P. berghei. Two polypeptides of 66 and 43 kDa molecular weights proved to be highly immunogenic. They exhibited a strong humoral immune response in mice as evident by high titres in ELISA and IFA. Protective immunity by these two antigens was apparent by in vivo and in vitro studies. These two proteins could further be analysed and used as antigens in malaria vaccine design.
