https://phaidra.vetmeduni.ac.at/o:2268 Comparative Analysis of the Exo-Erythrocytic Development of Five Lineages of Haemoproteus majoris, a Common Haemosporidian Parasite of European Passeriform Birds Duc, Mélanie Mélanie Duc 0000-0001-5468-2594 Nature Research Centre Valkiūnas, Gediminas Gediminas Valkiūnas 0000-0003-0594-0280 Nature Research Centre Weissenböck, Herbert Herbert Weissenböck 0000-0001-8197-6379 University of Veterinary Medicine Vienna Ilgūnas, Mikas Mikas Ilgūnas Nature Research Centre Matt, Julia Julia Matt University of Veterinary Medicine Vienna Nedorost, Nora Nora Nedorost University of Veterinary Medicine Vienna Iezhova, Tatjana Tatjana Iezhova Nature Research Centre Himmel, Tanja Tanja Himmel 0000-0001-9443-8967 University of Veterinary Medicine Vienna Harl, Josef Josef Harl 0000-0002-4915-3943 University of Veterinary Medicine Vienna MDPI text eng Haemoproteus parasites (Apicomplexa, Haemosporida) are widespread pathogens of birds, with a rich genetic (about 1900 lineages) and morphospecies (178 species) diversity. Nonetheless, their life cycles are poorly understood. The exo-erythrocytic stages of three Haemoproteus majoris (widespread generalist parasite) lineages have been previously reported, each in a different bird species. We aimed to further study and compare the development of five H. majoris lineages-hCCF5, hCWT4, hPARUS1, hPHSIB1, and hWW2-in a wider selection of natural avian hosts. A total of 42 individuals belonging to 14 bird species were sampled. Morphospecies and parasitemia were determined by microscopy of blood films, lineages by DNA-barcoding a 478 bp section of the cytochrome b gene, and exo-erythrocytic stages by histology and chromogenic in situ hybridization. The lineage hCWT4 was morphologically characterized as H. majoris for the first time. All lineage infections exclusively featured megalomeronts. The exo-erythrocytic stages found in all examined bird species were similar, particularly for the lineages hCCF5, hPARUS1, and hPHSIB1. Megalomeronts of the lineages hWW2 and hCWT4 were more similar to each other than to the former three lineages. The kidneys and gizzard were most often affected, followed by lungs and intestines; the site of development showed variation depending on the lineage. Avian Haemosporidians; Malaria Parasites; Host-Specificity; Plasmodium; Hematozoa http://creativecommons.org/licenses/by/4.0/ https://phaidra.vetmeduni.ac.at/api/object/o:2268/download 10.3390/pathogens12070898 https://phaidra.vetmeduni.ac.at/o:605 application/pdf Pathogens 12(7) (2023) Pathogens 12 7 1.06 MB 2023