Submitted to: Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/10/2010
Publication Date: 10/10/2010
Citation: Dubey, J.P., Yabsley, M. 2010. Besnoitia neotomofelis n. sp. (Protozoa: Apicomplexa) from the southern plains woodrat (Neotoma micropus). Parasitology. 137:1731-1747. Interpretive Summary: Besnoitia species are closely related to Toxoplasma gondii and Neospora caninum that cause abortion and mortality in livestock. These parasites have common antigens that pose problems in diagnosis. In the present paper, researchers describe a new species of Besnoitia that may help to study of the biology of these groups of organisms. The results will be of interest to biologists, parasitologists, and veterinarians.
Technical Abstract: Certain species of the protozoan genus Besnoitia cause clinical disease in livestock and wildlife. In the present paper a new species, Besnoitia neotomofelis is described from the southern planes woodrat (Neotoma micropus). The parasite was detected by bioassay of woodrat tissues in out bred Swiss Webster mice in an attempt to isolate Toxoplasma gondii. Initially, the organism was misdiagnosed as T. gondii because it was highly pathogenic for mice and its tachyzoites resembled T. gondii tachyzoites. Further studies revealed that it differed structurally and biologically from T. gondii. Tachyzoites were successfully cultivated and maintained in vitro in bovine monocytes and African green monkey kidney cells, and in vivo in mice. Non-dividing, uninucleate tachyzoites were approximately 1 x 5 µm in size. Longitudinally-cut bradyzoites in tissue sections measured 1.5-1.6 x 7.7-9.3 µm. Tissue cysts were microscopic, up to 210 µm long, and were infective orally to mice. Cats fed tissue cysts shed unsporulated 13 x 14 µm oocysts. All mice inoculated with woodrat Beanoitia died of acute besnoitiosis, irrespective of the dose, and Norwegian rats became infected but remained asymptomatic. Entero-epithelial stages (schizonts, gamonts) were found in cats fed tissue cysts. Large (up to 40 x 50 µm) first generation schizonts developed in the lamina propria of the small intestine of cats. A second generation of small sized (8 µm) schizont containing 4-8 merozoites was detected in enterocytes of small intestine. Gamonts and oocysts were seen in goblet cells of the intestinal epithelium. Tachyzoites were present in mesenteric lymph nodes of cats. Phylogenetic analysis indicated that this Besnoitia was related to other Besnoitia species from rodents, rabbits, and opossums. This woodrat-derived species of Besnoitia was distinct from the three other species of Besnoitia, B. wallacei, B. darlingi, and B. oryctofelisi, that utilize cats as a definitive host.