title: Description of the first cryptic avian malaria parasite, Plasmodium homocircumflexum n. sp., with experimental data on its virulence and development in avian hosts and mosquitoes.
abstract: For over 100 years studies on avian haemosporidian parasite species have relied on similarities in their morphology to establish a species concept. Some exceptional cases have also included information about the life cycle and sporogonic development. More than 50 avian Plasmodium spp. have now been described. However, PCR-based studies show a much broader diversity of haemosporidian parasites, indicating the possible existence of a diverse group of cryptic species. In the present study, using both similarity and phylogenetic species definition concepts, we believe that we report the first characterised cryptic speciation case of an avian Plasmodium parasite. We used sequence information on the mitochondrial cytochrome b gene and constructed phylogenies of identified Plasmodium spp. to define their position in the phylogenetic tree. After analysis of blood stages, the morphology of the parasite was shown to be identical to Plasmodium circumflexum. However, the geographic distribution of the new parasite, the phylogenetic information, as well as patterns of development of infection, indicate that this parasite differs from P. circumflexum. Plasmodium homocircumflexum n. sp. was described based on information about genetic differences from described lineages, phylogenetic position and biological characters. This parasite develops parasitemia in experimentally infected birds - the domestic canary Serinus canaria domestica, siskin Carduelis spinus and crossbill Loxia curvirostra. Anaemia caused by high parasitemia, as well as cerebral paralysis caused by exoerythrocytic stages in the brain, are the main reasons for mortality. Exoerythrocytic stages also form in other organs (heart, kidneys, liver, lungs, spleen, intestines and pectoral muscles). DNA amplification was unsuccessful from faecal samples of heavily infected birds. The sporogonic development initiates, but is abortive, at the oocyst stage in two common European mosquito species, Culex pipiens pipiens (forms pipiens and molestus) and Aedes vexans. Vectors of this Plasmodium sp. remain unknown.
authors.affiliation: Institute of Ecology, Nature Research Centre, Akademijos 2, Vilnius 2100, LT-08412, Lithuania. Electronic address: vaidas@ekoi.lt.
authors.forename: Vaidas
authors.initials: V
authors.lastname: Palinauskas
authors.affiliation: Institute of Ecology, Nature Research Centre, Akademijos 2, Vilnius 2100, LT-08412, Lithuania.
authors.forename: Rita
authors.initials: R
authors.lastname: Žiegytė
authors.affiliation: Institute of Ecology, Nature Research Centre, Akademijos 2, Vilnius 2100, LT-08412, Lithuania.
authors.forename: Mikas
authors.initials: M
authors.lastname: Ilgūnas
authors.affiliation: Institute of Ecology, Nature Research Centre, Akademijos 2, Vilnius 2100, LT-08412, Lithuania.
authors.forename: Tatjana A
authors.initials: TA
authors.lastname: Iezhova
authors.affiliation: Institute of Ecology, Nature Research Centre, Akademijos 2, Vilnius 2100, LT-08412, Lithuania.
authors.forename: Rasa
authors.initials: R
authors.lastname: Bernotienė
authors.affiliation: Biological Station Rybachy, Zoological Institute, Russian Academy of Sciences, Rybachy 238535, Kaliningrad Reg., Russia.
authors.forename: Casimir
authors.initials: C
authors.lastname: Bolshakov
authors.affiliation: Institute of Ecology, Nature Research Centre, Akademijos 2, Vilnius 2100, LT-08412, Lithuania.
authors.forename: Gediminas
authors.initials: G
authors.lastname: Valkiūnas
mesh_terms: D000330:Aedes; D000825:Animal Structures / Q000473:pathology; D000818:Animals; D001717:Birds; D016000:Cluster Analysis; D003465:Culex; D009033:Culicidae / Q000469:parasitology*; D045303:Cytochromes b / Q000235:genetics; D003584:Cytological Techniques; D016054:DNA, Protozoan / Q000737:chemistry / Q000235:genetics; D008289:Malaria, Avian / Q000469:parasitology* / Q000473:pathology; D024101:Mitochondrial Proteins / Q000235:genetics; D008969:Molecular Sequence Data; D058974:Phylogeography; D010961:Plasmodium / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification* / Q000502:physiology; D015800:Protozoan Proteins / Q000235:genetics; D017422:Sequence Analysis, DNA; D017385:Sequence Homology
chemical_list: D016054:DNA, Protozoan; D024101:Mitochondrial Proteins; D015800:Protozoan Proteins; D045303:Cytochromes b
keywords: Avian haemosporidian; Cryptic species; Experimental infection; Plasmodium homocircumflexum; Virulence; pCOLL4