title: The genome of Eimeria falciformis--reduction and specialization in a single host apicomplexan parasite.
abstract: BACKGROUND
  The phylum Apicomplexa comprises important unicellular human parasites such as Toxoplasma and Plasmodium. Eimeria is the largest and most diverse genus of apicomplexan parasites and some species of the genus are the causative agent of coccidiosis, a disease economically devastating in poultry. We report a complete genome sequence of the mouse parasite Eimeria falciformis. We assembled and annotated the genome sequence to study host-parasite interactions in this understudied genus in a model organism host.
  
  
  RESULTS
  The genome of E. falciformis is 44 Mb in size and contains 5,879 predicted protein coding genes. Comparative analysis of E. falciformis with Toxoplasma gondii shows an emergence and diversification of gene families associated with motility and invasion mainly at the level of the Coccidia. Many rhoptry kinases, among them important virulence factors in T. gondii, are absent from the E. falciformis genome. Surface antigens are divergent between Eimeria species. Comparisons with T. gondii showed differences between genes involved in metabolism, N-glycan and GPI-anchor synthesis. E. falciformis possesses a reduced set of transmembrane transporters and we suggest an altered mode of iron uptake in the genus Eimeria.
  
  
  CONCLUSIONS
  Reduced diversity of genes required for host-parasite interaction and transmembrane transport allow hypotheses on host adaptation and specialization of a single host parasite. The E. falciformis genome sequence sheds light on the evolution of the Coccidia and helps to identify determinants of host-parasite interaction critical for drug and vaccine development.
authors.forename: Emanuel
authors.initials: E
authors.lastname: Heitlinger
authors.forename: Simone
authors.initials: S
authors.lastname: Spork
authors.forename: Richard
authors.initials: R
authors.lastname: Lucius
authors.affiliation: Computational RNA Biology and Ageing, Max Plank Institute for Biology of Ageing, Joseph-Stelzmann Straße 9b, 50913 Cologne, Germany. christoph.dieterich@age.mpg.de.
authors.forename: Christoph
authors.initials: C
authors.lastname: Dieterich
mesh_terms: D000818:Animals; D000954:Antigens, Surface / Q000378:metabolism; D001482:Base Composition / Q000235:genetics; D001483:Base Sequence; D002874:Chromosome Mapping; D016000:Cluster Analysis; D003048:Coccidiosis / Q000469:parasitology; D004539:Eimeria / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D005260:Female; D063990:Gene Ontology; D059646:Genome Size; D018503:Genome, Protozoan; D006790:Host-Parasite Interactions / Q000235:genetics*; D006801:Humans; D008018:Life Cycle Stages; D051379:Mice; D058977:Molecular Sequence Annotation; D005810:Multigene Family; D016366:Open Reading Frames / Q000235:genetics; D010271:Parasites / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D010802:Phylogeny; D020543:Proteome / Q000378:metabolism
chemical_list: D000954:Antigens, Surface; D020543:Proteome