title: Gliding motility of Babesia bovis merozoites visualized by time-lapse video microscopy.
abstract: BACKGROUND
  Babesia bovis is an apicomplexan intraerythrocytic protozoan parasite that induces babesiosis in cattle after transmission by ticks. During specific stages of the apicomplexan parasite lifecycle, such as the sporozoites of Plasmodium falciparum and tachyzoites of Toxoplasma gondii, host cells are targeted for invasion using a unique, active process termed "gliding motility". However, it is not thoroughly understood how the merozoites of B. bovis target and invade host red blood cells (RBCs), and gliding motility has so far not been observed in the parasite.
  
  
  RESULTS
  Gliding motility of B. bovis merozoites was revealed by time-lapse video microscopy. The recorded images revealed that the process included egress of the merozoites from the infected RBC, gliding motility, and subsequent invasion into new RBCs. The gliding motility of B. bovis merozoites was similar to the helical gliding of Toxoplasma tachyzoites. The trails left by the merozoites were detected by indirect immunofluorescence assay using antiserum against B. bovis merozoite surface antigen 1. Inhibition of gliding motility by actin filament polymerization or depolymerization indicated that the gliding motility was driven by actomyosin dependent process. In addition, we revealed the timing of breakdown of the parasitophorous vacuole. Time-lapse image analysis of membrane-stained bovine RBCs showed formation and breakdown of the parasitophorous vacuole within ten minutes of invasion.
  
  
  CONCLUSIONS
  This is the first report of the gliding motility of B. bovis. Since merozoites of Plasmodium parasites do not glide on a substrate, the gliding motility of B. bovis merozoites is a notable finding.
authors.affiliation: National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Inada, Obihiro, Japan.
authors.forename: Masahito
authors.initials: M
authors.lastname: Asada
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Goto
authors.forename: Kazuhide
authors.initials: K
authors.lastname: Yahata
authors.forename: Naoaki
authors.initials: N
authors.lastname: Yokoyama
authors.forename: Satoru
authors.initials: S
authors.lastname: Kawai
authors.forename: Noboru
authors.initials: N
authors.lastname: Inoue
authors.forename: Osamu
authors.initials: O
authors.lastname: Kaneko
authors.forename: Shin-ichiro
authors.initials: S
authors.lastname: Kawazu
mesh_terms: D008841:Actin Cytoskeleton / Q000378:metabolism; D000818:Animals; D016793:Babesia bovis / Q000502:physiology*; D001404:Babesiosis / Q000378:metabolism / Q000469:parasitology; D002417:Cattle; D002418:Cattle Diseases / Q000378:metabolism / Q000469:parasitology; D004912:Erythrocytes / Q000378:metabolism / Q000469:parasitology; D052940:Merozoites; D018715:Microscopy, Video / Q000379:methods; D010271:Parasites / Q000502:physiology; D010961:Plasmodium / Q000502:physiology; D014122:Toxoplasma / Q000502:physiology