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Exploitation of the Leishmania exosomal pathway by Leishmania RNA virus 1


Leishmania are ancient eukaryotes that have retained the exosome pathway through evolution. Leishmania RNA virus 1 (LRV1)-infected Leishmania species are associated with a particularly aggressive mucocutaneous disease triggered in response to the double-stranded RNA (dsRNA) virus. However, it is unclear how LRV1 is exposed to the mammalian host cells. In higher eukaryotes, some viruses are known to utilize the host exosome pathway for their formation and cell-to-cell spread. As a result, exosomes derived from infected cells contain viral material or particles. Herein, we investigated whether LRV1 exploits the Leishmania exosome pathway to reach the extracellular environment. Biochemical and electron microscopy analyses of exosomes derived from LRV1-infected Leishmania revealed that most dsRNA LRV1 co-fractionated with exosomes, and that a portion of viral particles was surrounded by these vesicles. Transfer assays of LRV1-containing exosome preparations showed that a significant amount of parasites were rapidly and transiently infected by LRV1. Remarkably, these freshly infected parasites generated more severe lesions in mice than non-infected ones. Moreover, mice co-infected with parasites and LRV1-containing exosomes also developed a more severe disease. Overall, this work provides evidence that Leishmania exosomes function as viral envelopes, thereby facilitating LRV1 transmission and increasing infectivity in the mammalian host.

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Data availability

The data that support the findings of this study are all reported in this paper and are available upon request. All data files containing proteomic analysis are provided in the Supplementary Information with protein names, accession numbers and statistical analysis.

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Change history

  • 26 February 2019

    An amendment to this paper has been published and can be accessed via a link at the top of the paper.


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This work is supported by grants from the Canadian Institute of Health Research to M.O. A.d.S.L.F. is a recipient of a Brazilian CNPq Science without Borders studentship award.

Author information

M.O. designed and supervised the study. V.D.A. contributed to the development and the design of the study. V.D.A. performed all experiments. M.O., C.M. A.d.S.L.F. and V.D.A. analysed data. A.Z., V.C. and M.J. performed and analysed data from polysome experiments. A.d.S.L.F. and C.M. contributed to the organization of proteomic data files and submission of the manuscript. All authors read and approved the final manuscript.

Competing interests

The authors declare no competing interests.

Correspondence to Martin Olivier.

Supplementary information

  1. Supplementary Information

    Supplementary Notes, Supplementary References, Supplementary Figures 1–9, Supplementary Tables 1–6, Raw Image Figs. 1–5, and Raw Image Supplementary Figures 1, 7 and 8.

  2. Reporting Summary

  3. Dataset 1

    Total spectra of Leishmania exosomes using Leishmania braziliensis database.

  4. Dataset 2

    EmPAI values and ANOVA analysis of Leishmania exosomes using Leishmania braziliensis database.

  5. Dataset 3

    Total protein spectra of Leishmania promastigotes using Leishmania braziliensis database.

  6. Dataset 4

    EmPAI values and ANOVA analysis of Leishmania promastigotes using Leishmania braziliensis database.

  7. Dataset 5

    Total spectra of Leishmania exosome versus promastigote.

  8. Dataset 6

    EmPAI values and ANOVA analysis of Leishmania exosome versus promastigote.

  9. Dataset 7

    EmPAI values of Leishmania mexicana exosomes and promastigotes using Leishmania mexicana database.

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Fig. 1: L. guyanensis clone 21 (Lg21+) releases LRV1 RNA and proteins within exosomes.
Fig. 2: Lg21+ exosomes surround LRV1-like particles and protect the viral genome from enzymatic degradation.
Fig. 3: The proteome of Lg21+Exo is altered.
Fig. 4: The proteome of Lg21+ promastigotes is altered due to altered mRNA translation efficiency.
Fig. 5: LRV1 is favourably transferred from Lg21+ parasites to non-infected L. Viannia parasites when surrounded by exosomes.
Fig. 6: Lg21+ exosomes induce exacerbated cutaneous leishmaniasis.