Host transcriptional responses to high-and low-virulent avian malaria parasites

Research output: Contribution to journalArticle


The transcriptional response of hosts to genetically similar pathogens can vary substantially, with important implications for disease severity and host fitness. A low pathogen load can theoretically elicit both high and low host responses, as the outcome depends on both the effectiveness of the host at suppressing the pathogen and the ability of the pathogen to evade the immune system. Here, we investigate the transcriptional response of Eurasian siskins (Spinus spinus) to two closely related lineages of the malaria parasite Plasmodium relictum. Birds were infected with either the high-virulent lineage P. relictum SGS1, the low-virulent sister lineage P. relictum GRW4, or sham-injected (controls). Blood samples for RNA sequencing were collected at four time points during the course of infection, totaling 76 transcriptomes from 19 birds. Hosts infected with SGS1 experienced up to 87% parasitemia and major transcriptome shifts throughout the infection, and multiple genes showed strong correlation with parasitemia. In contrast, GRW4-infected hosts displayed low parasitemia (maximum 0.7%) with a minor transcriptional response. We furthermore demonstrate that the baseline gene expression levels of hosts prior to infection were irrelevant as immunocompetence markers, as they could not predict future pathogen load. This study shows that the magnitude of the host transcriptional response can differ markedly from related parasites with different virulence, and it enables a better understanding of the molecular interactions taking place between hosts and parasites.


External organisations
  • State Scientific Institute Nature Research Centre
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Microbiology in the medical area
  • Microbiology


  • Gene expression, Immune response, Parasitemia, Plasmodium, Transcriptome, Virulence
Original languageEnglish
Pages (from-to)1070–1084
Number of pages15
JournalAmerican Naturalist
Issue number6
Publication statusPublished - 2020 Jun
Publication categoryResearch