RESUMO
Malaria antibody detection is valuable in providing retrospective confirmation of an attack of malaria. Blood bank screening is another area were malaria serology is potentially useful. In the present study, we tested the presence of antibodies to Plasmodium falciparum in sera from blood bank donors of non-endemic and malaria-endemic areas of Venezuela. Sera from 1,000 blood donors were tested by an indirect immunofluorescent antibody (IFA) assay and an IgG-ELISA for the presence of malaria antibodies using a synchronized in vitro-cultured Venezuelan isolate of P. falciparum as the antigen source. A selected group of positive and negative sera (n = 100) was also tested by a dot-IgG-ELISA. Positive results (reciprocal titer > or = 40) were found in 0.8% and 3.8% of blood donors when tested by the IFA assay and in 0.8% and 2% (optical density > or = 0.2) when tested by the IgG-ELISA in Caracas (non-endemic area) and Bolivar City (endemic area), respectively. The presence of anti-malarial antibodies in some sera from non-endemic areas such as Caracas reflects the increased potential risk of post-transfusional malaria in those areas due to the mobility of the blood donors. The data obtained indicate the need to implement new blood donor policy in blood banks in developing areas. Our results also indicate that the IFA assay is the most reliable test to use in malaria serodiagnosis.
Assuntos
Anticorpos Antiprotozoários/sangue , Doadores de Sangue , Portador Sadio/imunologia , Malária Falciparum/imunologia , Plasmodium falciparum/imunologia , Adolescente , Adulto , Animais , Antígenos de Protozoários/biossíntese , Bancos de Sangue , Western Blotting , Portador Sadio/epidemiologia , Ensaio de Imunoadsorção Enzimática , Reações Falso-Positivas , Feminino , Técnica Indireta de Fluorescência para Anticorpo , Humanos , Malária Falciparum/epidemiologia , Masculino , Pessoa de Meia-Idade , Plasmodium falciparum/isolamento & purificação , Curva ROC , Sensibilidade e Especificidade , Estatísticas não Paramétricas , Venezuela/epidemiologiaRESUMO
Proteolysis of endogenous proteins may play a key role in the adaptation of T. cruzi to the different host environments to which it is exposed during its complex life cycle. For this reason, we have attempted to study the intracellular pathways of protein degradation in the non infective epimastigotes form (EP strain) of T. cruzi. Following intracellular proteolysis by pulse chase experiments with 35 S methionine, we observed a significant inhibition (50%) of the degradation of endogenous proteins in log phase parasites in the presence of inhibitors of lysosomal functions, such as chloroquine and E 64. A significant increase in proteolysis was observed in stationary phase parasites which was reverted to log phase values by supplementing the chase medium with 0.5% glucose or 10% serum, or in the presence of chloroquine. Under this condition of nutritional stress, we could observe an increase in the activity of acid proteases. A significant increase in the degradation rates was observed when abnormal proteins were induced in the parasite by amino acid analogs and puromycin. This increase was not affected by E 64, suggesting the participation of non lysosomal mechanisms in the degradation of rapidly degradable abnormal proteins. Under these conditions, we could observe an increase in high molecular weight conjugates of ubiquitin with respect to endogenous proteins. These results suggest the importance of lysosomal mechanisms in the degradation of cellular proteins in nutritional optimal conditions and during nutritional deprivation, and the possible involvement of the ubiquitin system in the degradation of high turnover proteins.
Assuntos
Peptídeo Hidrolases/metabolismo , Proteínas de Protozoários/metabolismo , Trypanosoma cruzi/metabolismo , Animais , Cloroquina/farmacologia , Cisteína Endopeptidases/metabolismo , Concentração de Íons de Hidrogênio , Membranas Intracelulares/metabolismo , Leucina/análogos & derivados , Leucina/farmacologia , Peso Molecular , Inibidores de Proteases/farmacologia , Puromicina/farmacologia , Fatores de Tempo , Trypanosoma cruzi/enzimologia , Trypanosoma cruzi/crescimento & desenvolvimento , Ubiquitinas/metabolismoRESUMO
The proteolytic pattern of Trypanosoma cruzi epimastigotes was studied using electrophoresis in gelatin containing SDS polyacrylamide gels. Under conditions that represent a nutritional stress such as the depletion of glucose in an axenic medium the results obtained showed a significant increase in the activity of two proteases of M(r) = 50,000 and M(r) = 60,000 as well as the appearance of higher molecular weight bands during the transition from log to stationary phase parasites. The use of different protease inhibitors strongly suggests that all these proteases are of the cysteine type, and their acid pH optimal would be in agreement with the possible localization in the parasite lysosomes. The reincubation of stationary phase parasites in fresh LIT medium or the addition of 0.4% glucose partially reverted the proteolytic pattern to that observed in log phase parasites. The regulation in the activity of these enzymes could be related to the well established use of amino acids for catabolic purpose after depletion of the medium glucose.