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Pathogenicity of Leishmania donovani is associated with the high expression of a group low molecular weight proteins.

Mitra P - Trop Parasitol (2015 Jul-Dec)

Bottom Line: It has been proposed that the loss of pathogenicity is associated with the gradual disappearance of selective parasite proteins.We observed a gradual and significant downregulation of expression of a group of low molecular weight proteins (LMW, molecular weight 20-30 kDa) which are associated with loss of pathogenicity.Therefore, our data strongly support the hypothesis that the loss of pathogenicity of L. donovani is associated with a change in antigenic profile, but not due the selective deletion of pathogenic clones.

View Article: PubMed Central - PubMed

Affiliation: Department of Pharmacy, University of Queensland, Woolloongabba, QLD 4122, Australia.

ABSTRACT

Background: With few exceptions, members of the Leishmania donovani complex such as L. donovani, L. infantum and L. chagashi are the etiological agents of visceral leishmaniasis or kala-azar. Promastigotes of Leishmania spp. lose their Pathogenicity; the ability to establish infection in a susceptible host, after prolonged culture. The molecular basis of this evolution of pathogenic to nonpathogenic culture has not been very well understood. It has been proposed that the loss of pathogenicity is associated with the gradual disappearance of selective parasite proteins. An alternative hypothesis is that during prolonged culture, the pathogenic clonal population of the parasite is deleted from the mixed population due to their selection pressure. This clonal deletion is proposed to be responsible for the emergence of the nonpathogenic population.

Study methodology and results: We have a done a series of two-dimensional polyacrylamide gel electrophoresis followed by western blot experiments to study the antigenic profile of few L. donovani isolates of Indian origin. We observed a gradual and significant downregulation of expression of a group of low molecular weight proteins (LMW, molecular weight 20-30 kDa) which are associated with loss of pathogenicity. These proteins are recognized only by antiserum raised against the whole cell extract of one of the pathogenic Indian L. donovani isolates, Ag83, and remained undetected by antiserum raised against the nonpathogenic AG83 isolates. These LMW proteins were also present in the nonpathogenic extract in very low levels and remained undetected by the virulent serum, indicating a phenomenon of simultaneous downregulation of the expression and altered immunogenicity. LMW proteins were universally expressed in all early passage Indian isolate we tested and also detected in two clones obtained from pathogenic parasite culture. The antigenic patterns of none of the eight clones obtained from nonpathogenic culture were not exactly similar with the pathogenic clones.

Conclusion: Therefore, our data strongly support the hypothesis that the loss of pathogenicity of L. donovani is associated with a change in antigenic profile, but not due the selective deletion of pathogenic clones.

No MeSH data available.


Related in: MedlinePlus

Low molecular weight promastigote proteins are not exposed to the parasite surface. Approximately, 4 × 106 AG83 pathogenic promastigotes were harvested and subjected to radio-iodination. Extract of radio labelled parasite protein (100μg) were analysed by 2D-PAGE-immunoblotting experiment using virulent serum.
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Figure 9: Low molecular weight promastigote proteins are not exposed to the parasite surface. Approximately, 4 × 106 AG83 pathogenic promastigotes were harvested and subjected to radio-iodination. Extract of radio labelled parasite protein (100μg) were analysed by 2D-PAGE-immunoblotting experiment using virulent serum.

Mentions: Cell surface proteins of promastigotes are more immunogenic in nature than proteins that functionally participate in parasites metabolic pathways mostly because they are modified by other macromolecules such as polysaccharides, long chain fatty acids, etc. To determine the expression of LMW on the surface of the parasite, live AG83 promastigotes were radio-iodinated, and the radiolabeled parasite extract was analyzed by 2D-PAGE followed by western blotting by virulent serum. The same blot was exposed to detect the radiolabeled proteins. Though few proteins were detected in the autoradiogram, LMW proteins were not detected by radio-iodination [Figure 7].


Pathogenicity of Leishmania donovani is associated with the high expression of a group low molecular weight proteins.

Mitra P - Trop Parasitol (2015 Jul-Dec)

Low molecular weight promastigote proteins are not exposed to the parasite surface. Approximately, 4 × 106 AG83 pathogenic promastigotes were harvested and subjected to radio-iodination. Extract of radio labelled parasite protein (100μg) were analysed by 2D-PAGE-immunoblotting experiment using virulent serum.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4557149&req=5

Figure 9: Low molecular weight promastigote proteins are not exposed to the parasite surface. Approximately, 4 × 106 AG83 pathogenic promastigotes were harvested and subjected to radio-iodination. Extract of radio labelled parasite protein (100μg) were analysed by 2D-PAGE-immunoblotting experiment using virulent serum.
Mentions: Cell surface proteins of promastigotes are more immunogenic in nature than proteins that functionally participate in parasites metabolic pathways mostly because they are modified by other macromolecules such as polysaccharides, long chain fatty acids, etc. To determine the expression of LMW on the surface of the parasite, live AG83 promastigotes were radio-iodinated, and the radiolabeled parasite extract was analyzed by 2D-PAGE followed by western blotting by virulent serum. The same blot was exposed to detect the radiolabeled proteins. Though few proteins were detected in the autoradiogram, LMW proteins were not detected by radio-iodination [Figure 7].

Bottom Line: It has been proposed that the loss of pathogenicity is associated with the gradual disappearance of selective parasite proteins.We observed a gradual and significant downregulation of expression of a group of low molecular weight proteins (LMW, molecular weight 20-30 kDa) which are associated with loss of pathogenicity.Therefore, our data strongly support the hypothesis that the loss of pathogenicity of L. donovani is associated with a change in antigenic profile, but not due the selective deletion of pathogenic clones.

View Article: PubMed Central - PubMed

Affiliation: Department of Pharmacy, University of Queensland, Woolloongabba, QLD 4122, Australia.

ABSTRACT

Background: With few exceptions, members of the Leishmania donovani complex such as L. donovani, L. infantum and L. chagashi are the etiological agents of visceral leishmaniasis or kala-azar. Promastigotes of Leishmania spp. lose their Pathogenicity; the ability to establish infection in a susceptible host, after prolonged culture. The molecular basis of this evolution of pathogenic to nonpathogenic culture has not been very well understood. It has been proposed that the loss of pathogenicity is associated with the gradual disappearance of selective parasite proteins. An alternative hypothesis is that during prolonged culture, the pathogenic clonal population of the parasite is deleted from the mixed population due to their selection pressure. This clonal deletion is proposed to be responsible for the emergence of the nonpathogenic population.

Study methodology and results: We have a done a series of two-dimensional polyacrylamide gel electrophoresis followed by western blot experiments to study the antigenic profile of few L. donovani isolates of Indian origin. We observed a gradual and significant downregulation of expression of a group of low molecular weight proteins (LMW, molecular weight 20-30 kDa) which are associated with loss of pathogenicity. These proteins are recognized only by antiserum raised against the whole cell extract of one of the pathogenic Indian L. donovani isolates, Ag83, and remained undetected by antiserum raised against the nonpathogenic AG83 isolates. These LMW proteins were also present in the nonpathogenic extract in very low levels and remained undetected by the virulent serum, indicating a phenomenon of simultaneous downregulation of the expression and altered immunogenicity. LMW proteins were universally expressed in all early passage Indian isolate we tested and also detected in two clones obtained from pathogenic parasite culture. The antigenic patterns of none of the eight clones obtained from nonpathogenic culture were not exactly similar with the pathogenic clones.

Conclusion: Therefore, our data strongly support the hypothesis that the loss of pathogenicity of L. donovani is associated with a change in antigenic profile, but not due the selective deletion of pathogenic clones.

No MeSH data available.


Related in: MedlinePlus