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Infection by the Lungworm Rhabdias pseudosphaerocephala Affects the Expression of Immune-Related microRNAs by Its
Tsering C L Chan1, Boris Yagound1, Gregory P Brown2
1Ecology & Evolution Research Centre, School of Biological, Earth and Environmental Sciences, University of New South Wales, UNSW, Sydney, New South Wales, Australia.
Abstract:
Parasites may suppress the immune function of infected hosts using microRNAs (miRNAs) to prevent protein production. Nonetheless, little is known about the diversity of miRNAs and their mode(s) of action. In this study, we investigated the effects of infection by a parasitic lungworm (Rhabdias pseudosphaerocephala) on miRNA and mRNA expression of its host, the invasive cane toad (Rhinella marina). To investigate the cane toad's innate and adaptive immune response to this parasite, we compared miRNA and mRNA expression in naïve toads that had never been infected by lungworms to toads that were infected with lungworms for the first time in their lives, and toads that were infected the second time in their lives (i.e., had two consecutive infections). In total, we identified 101 known miRNAs and 86 potential novel miRNAs. Compared to uninfected and single-infection toads, multiple-infection animals drastically downregulated three miRNAs. These miRNAs were associated with gene pathways related to the immune response, potentially reflecting the immunosuppression of cane toads by their parasites. Infected hosts did not respond with substantially differential mRNA transcription; only one gene was differentially expressed between control and single-infection hosts. Our study suggests that miRNA may play an important role in mediating host-parasite interactions in a system in which an ongoing range expansion by the host has generated substantial divergence in host-parasite interactions.
Insights
Parasitic lungworms suppress cane toad immunity by downregulating specific microRNAs (miRNAs). This study reveals how these parasites manipulate host immune responses, impacting host-parasite interactions during range expansion.
Area of Science:
- Parasitology
- Immunology
- Genomics
Background:
- Parasites can evade host immunity by modulating gene expression using microRNAs (miRNAs).
- The specific mechanisms and diversity of miRNAs involved in host-parasite interactions remain largely unexplored.
- Cane toads (Rhinella marina) are invasive hosts, and understanding their immune response to parasites like lungworms (Rhabdias pseudosphaerocephala) is crucial.
Purpose of the Study:
- To investigate the impact of parasitic lungworm infection on miRNA and mRNA expression in the invasive cane toad.
- To identify known and novel miRNAs involved in the cane toad's immune response to infection.
- To elucidate the role of miRNAs in mediating host-parasite interactions, particularly in the context of host range expansion.
Main Methods:
- Comparative analysis of miRNA and mRNA expression profiles in cane toads with no infection, single infection, and multiple infections.
- Identification of known and novel microRNAs using small RNA sequencing.
- Bioinformatic analysis to associate differentially expressed miRNAs with immune response pathways.
Main Results:
- Identification of 101 known and 86 potential novel miRNAs in cane toads.
- Significant downregulation of three specific miRNAs in multiply infected toads compared to uninfected and singly infected toads.
- Minimal differential mRNA expression observed, suggesting miRNAs play a primary role in immune modulation.
Conclusions:
- MicroRNAs play a significant role in the immunosuppressive strategies employed by parasitic lungworms in cane toads.
- The identified miRNAs are linked to immune response pathways, indicating a targeted manipulation of the host immune system.
- These findings provide insights into host-parasite co-evolutionary dynamics, especially in invasive species with expanding ranges.
