title: Differences in clinical manifestations and hematological and serological responses after experimental infection with genetic variants of Anaplasma phagocytophilum in sheep.
abstract: Five-month-old lambs were experimentally infected with two 16S rRNA genetic variants of Anaplasma phagocytophilum, variants 1 (GenBank accession no. M73220) and 2 (GenBank accession no. AF336220). Additional sequencing of the groESL heat shock operon gene indicated that these variants differ in three nucleotides at positions 782, 824, and 890. The variants were obtained by blood sampling of A. phagocytophilum-infected lambs from one sheep flock in Norway and were stored at -70 degrees C with 10% dimethyl sulfoxide as a cryoprotectant before being inoculated intravenously into susceptible lambs. The infectious blood contained, per ml, approximately 0.5 x 10(6) neutrophils infected with either of the variants. Six weeks after the primary inoculation, the lambs were challenged with the same infectious dose of the heterologous variant. The results of the study indicate a marked difference in clinical manifestation, neutropenia, antibody response, and cross-protection after experimental infection with the two variants of A. phagocytophilum.
authors.affiliation: Department of Sheep and Goat Research, Norwegian School of Veterinary Science, Sandnes, Norway. Snorre.Stuen@veths.no
authors.forename: Snorre
authors.initials: S
authors.lastname: Stuen
authors.forename: Karin
authors.initials: K
authors.lastname: Bergström
authors.forename: Miroslav
authors.initials: M
authors.lastname: Petrovec
authors.forename: Ingrid
authors.initials: I
authors.lastname: Van de Pol
authors.forename: Leo M
authors.initials: LM
authors.lastname: Schouls
mesh_terms: D041081:Anaplasma phagocytophilum / Q000235:genetics / Q000276:immunology / Q000472:pathogenicity*; D000818:Animals; D018834:Chaperonin 60 / Q000235:genetics; D003429:Cross Reactions; D004269:DNA, Bacterial / Q000235:genetics; D004275:DNA, Ribosomal / Q000235:genetics; D016873:Ehrlichiosis / Q000097:blood / Q000276:immunology / Q000382:microbiology / Q000662:veterinary*; D014644:Genetic Variation; D008969:Molecular Sequence Data; D009503:Neutropenia / Q000209:etiology; D009504:Neutrophils / Q000382:microbiology; D009876:Operon; D012329:RNA, Bacterial / Q000235:genetics; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012756:Sheep; D012757:Sheep Diseases / Q000097:blood / Q000276:immunology / Q000382:microbiology*; D013045:Species Specificity
chemical_list: D018834:Chaperonin 60; D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D012329:RNA, Bacterial; D012336:RNA, Ribosomal, 16S