Dados do Trabalho

Título

ABSENCE OF TYPICAL HALLMARKS OF APOPTOSIS IN CELL DEATH OF P. vivax-BLOOD STAGES

Introdução

Elucidation of pathways regulating parasitic cell death is believed to contribute to identification of novel therapeutic targets for protozoan diseases and, in this context, apoptosis-like cell death has been reported in different groups of protozoa, in which a family of cysteine-dependent proteases, called metacaspases, seems to be involved. In Plasmodium, apoptotic markers have been detected in P. falciparum, P. yoelii and P. berghei, with no study focusing on P. vivax cell death.

Objetivo(s)

Investigate the susceptibility of P. vivax to undergo apoptotic cell death.

Material e Métodos

Trophozoites were enriched from blood samples of malaria vivax patients and then, incubated in the presence of chloroquine or classical inducers of apoptosis (staurosporine and camptothecin). Parasite growth and viability as well as apoptotic events were detected by flow cytometry assays, and cell morphology was examined using transmission electron microscopy. Additionally, real-time quantitative PCR was used to estimate the expression of P. vivax metacaspase 1 (PvMCA1) gene.

Resultados e Conclusão

All stimuli used inhibited the intraerythrocytic development, which was accompanied by a decrease in parasitic viability, as evidenced by analysis of the DNA content and plasmodial mitochondrial activity, respectively. However, typical signs of apoptosis, such as DNA fragmentation, chromatin condensation and nuclear segregation, as well as augmented expression of metacaspase gene, were not detected in cell death-induced parasites. On the other hand, a relation between the parasite development and PvMCA1 expression was observed in non-treated parasites.
Thus, the results indicate that P. vivax blood forms are not susceptible to apoptosis-like cell death, while suggest that metacaspase can be involved in processes related to parasite growth. Further studies are still required to better describe cell death phenomena in P. vivax.

Palavras-chave

P. vivax; Cell death; Apoptosis; Metacaspase