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Recruitment of erythrocyte membrane components by apicomplexan parasites Babesia divergens and Plasmodium falciparum
There are a few parasitic protozoa that infect erythrocyte and the erythrocyte does not play any essential or even obligatory role in the parasite survival and subsequent development for most of these, but for two apicomplexan parasites of the genera Plasmodium and Babesia. For these parasites, the...
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| Format: | Dissertation |
| Sprache: | Englisch |
| Veröffentlicht: |
Philipps-Universität Marburg
2015
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| Zusammenfassung: | There are a few parasitic protozoa that infect erythrocyte and the erythrocyte does not play any essential or even obligatory role in the parasite survival and subsequent development for most of these, but for two apicomplexan parasites of the genera Plasmodium and Babesia. For these parasites, the host erythrocyte plays a vital role in survival and in associated pathogenicity (directly or indirectly). Moreover these two parasites are also known to alter the host cell differentially; for what seems customising it to specific requirements. Of these alterations one prominent is the formation of the unique vacuolar compartment ‘parasitophorus vacuole’ surrounded by ‘parasitophorus vacuole membrane. However our idea about the contribution of the host cell towards the PVM is limited. In absence of any marker for PVM, the formation and the fate too had not been studied in details but in a few apicomplexa.
I took the advantage of a Babesia divergens strain, adapted to human erythrocytes (B. divergens normally infect cattle or immuno-suppressed humans) and used Plasmodium falciparum clone 3D7 (routinely cultured in human erythrocyte) and did a detailed comparative analysis between the PVM formed the invasion of these two related obligate intracellular apicomplexa in identical host cell (erythrocyte).
Ultrastructure analysis of infected erythrocytes revealed that unlike Plasmodium falciparum, which remained inside the PV all along the intra-erythrocytic development, the Babesia divergens lost its PVM sometime soon after invasion: an observation, possibly indicating that the maintenance of the PV per se as a protective environment is not a prerequisite for this parasite growth.
Thereafter with a strict selection of erythrocyte membrane proteins (membrane anchor containing, membrane spanning, cytoskeletal, cytoskeleton associated and erythrocyte surface receptor), reportedly internalized or discounted during the invasion by P. falciparum and present or absent on the newly formed PVM based on their association with erythrocyte cytoskeleton, I performed epifluorescence microscopy and biochemical analysis. I aimed to demonstrate the fate of these proteins parallaly in P. falciparum and B. divergens infected erythrocytes. I took help of immuno-electron microscopy to confirm my results.
With fluorescence microscopy, I could show that both of the parasites took up labelled lipid components were from the labelled erythrocyte surface and recruited them onto their respective PVMs. However there was a difference in the recruitment of proteins between these two. A high copy number, erythrocyte membrane protein (Band 3) and a cytoskeletal protein (Spectrin) was found present in the PVM of Babesia divergens but not in PVM of Plasmodium falciparum. Parallel to this in B. divergens infected erythrocytes; PVM-localization could not be confirmed for few proteins, for which incorporation into the PVM of P. falciparum had been suggested in several reports.
Altogether the results obtained from this study suggest that the recruitment or exclusion of specific membrane components is determined in a parasite specific manner and is not regulated by the intrinsic properties of the erythrocyte membrane. However incorporation or exclusion of different proteins may also reflect difference in the preferred entry sites for these parasites, leading ultimately to the difference in components of the PVM and show the possibility of using such parasites as molecular tools for understanding the inducible physiological processes, generally silent in such quiescent cells (erythrocyte). |
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| Umfang: | 182 Seiten |
| DOI: | 10.17192/z2015.0410 |