title: Passive immunization does not provide protection against experimental infection with Mycoplasma haemofelis.
abstract: Mycoplasma haemofelis (Mhf) is the most pathogenic feline hemotropic mycoplasma. Cats infected with Mhf that clear bacteremia are protected from Mhf reinfection, but the mechanisms of protective immunity are unresolved. In the present study we investigated whether the passive transfer of antibodies from Mhf-recovered cats to naïve recipient cats provided protection against bacteremia and clinical disease following homologous challenge with Mhf; moreover, we characterized the immune response in the recipient cats. Ten specified pathogen-free (SPF) cats were transfused with pooled plasma from cats that had cleared Mhf bacteremia; five control cats received plasma from naïve SPF cats. After homologous challenge with Mhf, cats were monitored for 100 days using quantitative PCR, hematology, blood biochemistry, Coombs testing, flow cytometry, DnaK ELISA, and red blood cell (RBC) osmotic fragility (OF) measurement. Passively immunized cats were not protected against Mhf infection but, compared to control cats, showed significantly higher RBC OF and B lymphocyte (CD45R/B220(+)) counts and occasionally higher lymphocyte, monocyte and activated CD4(+) T lymphocyte (CD4(+)CD25(+)) counts; they also showed higher bilirubin, total protein and globulin levels compared to those of control cats. At times of peak bacteremia, a decrease in eosinophils and lymphocytes, as well as subsets thereof (B lymphocytes and CD5(+), CD4(+) and CD8(+) T lymphocytes), and an increase in monocytes were particularly significant in the passively immunized cats. In conclusion, passive immunization does not prevent bacteremia and clinical disease following homologous challenge with Mhf, but enhances RBC osmotic fragility and induces a pronounced immune response.
authors: Clinical Laboratory, Vetsuisse Faculty, University of Zurich, Winterthurerstr. 260, 8057, Zurich, Switzerland.|Center for Clinical Studies, Vetsuisse Faculty, University of Zurich, Winterthurerstr. 260, 8057, Zurich, Switzerland.
authors: Sarah
authors: S
authors: Sugiarto
authors: Clinical Laboratory, Vetsuisse Faculty, University of Zurich, Winterthurerstr. 260, 8057, Zurich, Switzerland.|Center for Clinical Studies, Vetsuisse Faculty, University of Zurich, Winterthurerstr. 260, 8057, Zurich, Switzerland.
authors: Andrea M
authors: AM
authors: Spiri
authors: Clinical Laboratory, Vetsuisse Faculty, University of Zurich, Winterthurerstr. 260, 8057, Zurich, Switzerland.|Center for Clinical Studies, Vetsuisse Faculty, University of Zurich, Winterthurerstr. 260, 8057, Zurich, Switzerland.
authors: Barbara
authors: B
authors: Riond
authors: Clinical Laboratory, Vetsuisse Faculty, University of Zurich, Winterthurerstr. 260, 8057, Zurich, Switzerland.|Center for Clinical Studies, Vetsuisse Faculty, University of Zurich, Winterthurerstr. 260, 8057, Zurich, Switzerland.
authors: Marilisa
authors: M
authors: Novacco
authors: Clinical Laboratory, Vetsuisse Faculty, University of Zurich, Winterthurerstr. 260, 8057, Zurich, Switzerland.|Center for Clinical Studies, Vetsuisse Faculty, University of Zurich, Winterthurerstr. 260, 8057, Zurich, Switzerland.
authors: Angelina
authors: A
authors: Oestmann
authors: Laboratory of Clinical Research on Dermatozoonosis in Domestic Animals, National Institute of Infectiology, Oswaldo Cruz Foundation, Rio de Janeiro, Brazil.
authors: Luisa H Monteiro
authors: LH
authors: de Miranda
authors: Clinical Laboratory, Vetsuisse Faculty, University of Zurich, Winterthurerstr. 260, 8057, Zurich, Switzerland.|Center for Clinical Studies, Vetsuisse Faculty, University of Zurich, Winterthurerstr. 260, 8057, Zurich, Switzerland.
authors: Marina L
authors: ML
authors: Meli
authors: Clinic for Small Animal Internal Medicine, Vetsuisse Faculty, University of Zurich, Winterthurerstr. 260, 8057, Zurich, Switzerland.
authors: Felicitas S
authors: FS
authors: Boretti
authors: Clinical Laboratory, Vetsuisse Faculty, University of Zurich, Winterthurerstr. 260, 8057, Zurich, Switzerland.|Center for Clinical Studies, Vetsuisse Faculty, University of Zurich, Winterthurerstr. 260, 8057, Zurich, Switzerland.
authors: Regina
authors: R
authors: Hofmann-Lehmann
authors: Clinical Laboratory, Vetsuisse Faculty, University of Zurich, Winterthurerstr. 260, 8057, Zurich, Switzerland. bwilli@vetclinics.uzh.ch.|Clinic for Small Animal Internal Medicine, Vetsuisse Faculty, University of Zurich, Winterthurerstr. 260, 8057, Zurich, Switzerland. bwilli@vetclinics.uzh.ch.
authors: Barbara
authors: B
authors: Willi
mesh_terms: D000818:Animals; D016470:Bacteremia / Q000276:immunology / Q000382:microbiology / Q000517:prevention & control / Q000662:veterinary; D058491:Bacterial Load / Q000662:veterinary; D002371:Cat Diseases / Q000276:immunology / Q000382:microbiology / Q000517:prevention & control*; D002415:Cats; D005434:Flow Cytometry / Q000662:veterinary; D007111:Immunity, Cellular / Q000276:immunology; D056724:Immunity, Humoral / Q000276:immunology; D007116:Immunization, Passive / Q000379:methods / Q000662:veterinary*; D008297:Male; D009174:Mycoplasma / Q000276:immunology*; D009175:Mycoplasma Infections / Q000276:immunology / Q000382:microbiology / Q000517:prevention & control / Q000662:veterinary*