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Abstract The malaria parasitePlasmodium relictum(lineage GRW4) was introduced less than a century ago to the native avifauna of Hawaiʻi, where it has since caused major declines of endemic bird populations. One of the native bird species that is frequently infected with GRW4 is the Hawaiʻi ʻamakihi (Chlorodrepanis virens). To achieve a better understanding of the transcriptional activities of this virulent parasite, we performed a controlled challenge experiment of 15 ʻamakihi that were infected with GRW4. Blood samples containing malaria parasites were collected at two time points (intermediate and peak infection stages) from host individuals that were either experimentally infected by mosquitoes or inoculated with infected blood. We then used RNA sequencing to assemble a high‐quality blood transcriptome ofP. relictumGRW4, allowing us to quantify parasite expression levels inside individual birds. We found few significant differences (one to two transcripts) in GRW4 expression levels between host infection stages and between inoculation methods. However, 36 transcripts showed differential expression levels among all host individuals, indicating a potential presence of host‐specific gene regulation across hosts. To reduce the extinction risk of the remaining native bird species in Hawaiʻi, genetic resources of the localPlasmodiumlineage are needed to enable further molecular characterization of this parasite. Our newly built Hawaiian GRW4 transcriptome assembly, together with analyses of the parasite's transcriptional activities inside the blood of Hawaiʻi ʻamakihi, can provide us with important knowledge on how to combat this deadly avian disease in the future.
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This content will become publicly available on January 27, 2026
Unraveling the host range of Plasmodium huffi : morphological, histopathological and molecular characterization in red-legged seriemas from Brazil
Abstract AvianPlasmodiumparasites can be pathogenic to their vertebrate hosts. Although cases of anaemia are frequently reported in parasitized birds, the potential damage caused by the parasite during the exoerythrocytic reproduction phase remains poorly investigated. Here, we report 2 individuals of red-legged seriemas (Cariama cristata) infected with 2 different lineages ofPlasmodium huffi, one of them exhibiting potential malarial-compatible tissue lesions in the spleen, liver, brain and lungs, alongside molecular confirmation of parasite presence in the spleen. Previously classified as specific to birds from the order Piciformes, this parasite has shown different associated lineages amplified across diverse host orders in South America (Anseriformes, Charadriiformes, Columbiformes, Galliformes, Pelecaniformes and Passeriformes). Those infections, however, were defined as abortive due to the absence of gametocytes visualized in blood smear slides. Herein, we confirmP. huffias a generalist parasite based on the first morphological characterization in the peripheral blood of a bird outside the Piciformes order. This is also the first morphological and molecular description of aPlasmodiumspecies in Cariamiformes. In addition to the morphological analyses, we have also proposed a novel phylogenetic hypothesis based on the partialcytbgene and the near-complete mitochondrial genome of this parasite. Our findings support that the division of the genusPlasmodiuminto subgenera is not monophyletic, asP.(Huffia) huffiand its associated lineages cluster more closely withPlasmodium(Haemamoeba) gallinaceumthan withPlasmodium(Huffia) elongatum.
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- Award ID(s):
- 2146653
- PAR ID:
- 10590652
- Publisher / Repository:
- Cambridge University Press
- Date Published:
- Journal Name:
- Parasitology
- ISSN:
- 0031-1820
- Page Range / eLocation ID:
- 1 to 16
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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