title: Evaluation of cell-mediated immune responses and bacterial clearance in 6-10 months old water buffalo (Bubalus bubalis) experimentally vaccinated with four dosages of commercial Brucella abortus strain RB51 vaccine.
abstract: Thirty water buffalo, obtained from a brucellosis-free farm, were used to evaluate cell-mediated immune responses and bacterial clearance in response to vaccination with Brucella abortus strain RB51 (RB51) in a dose-response study. The animals were randomly divided into five treatment groups. Groups I--V received the recommended dose (RD) of RB51 vaccine once, RD twice 4 weeks apart, double RD once, double RD twice 4 weeks apart and saline once, respectively. Cell-mediated immune response to RB51 was assessed by the histological examination of haematoxylin and eosin (H&E) stained sections of lymph nodes draining the sites of inoculation and by comparison of stimulation indices (SI) derived from gamma interferon (IFN-gamma) assay. A mixture of cytoplasmic proteins from B. melitensis B115 (brucellergene) was used as a specific antigenic stimulus to peripheral blood mononuclear cells (PBMC) and lymph node mononuclear cells (LNMC) up to 22 post-initial-inoculation week (PIW). Supernatants harvested at 18-24h after the in vitro antigenic stimulus were assayed for their IFN-gamma content by using a commercial sandwich enzyme-linked immunosorbent assay (ELISA) kit. Clearance of RB51 was assessed by the sequential immunohistochemical examination of sections of draining lymph nodes post-inoculation. There was no observable expansion of the deep cortex of lymph nodes on H&E sections indicating poor T-cell stimulation. All group V (control) water buffalo PBMC ELISA values were negative (SI<2.2) at all PIW sampling intervals. Overall PBMC IFN-gamma assay detected vaccinates from treatment groups' I--IV 67% (4/6), 83% (5/6), 33% (2/6) and 67% (4/6), respectively. LNMC IFN-gamma assay was unimpressive and there was a negative correlation (--.08) between the results of PBMC and LNMC of IFN-gamma assay. Clearance of RB51 occurred between 4 and 6 PIW in treatment groups I and III and between 6 and 12 PIW in groups II and IV. RB51 was not detected in any of the control animals at sampling intervals post-inoculation.
authors.affiliation: Faculty of Medical Sciences, School of Veterinary Medicine, University of the West Indies, Champs Fleurs, Trinidad and Tobago. michaeldiptee@hotmail.com
authors.forename: M D
authors.initials: MD
authors.lastname: Diptee
authors.forename: A A
authors.initials: AA
authors.lastname: Adesiyun
authors.forename: Z
authors.initials: Z
authors.lastname: Asgarali
authors.forename: M
authors.initials: M
authors.lastname: Campbell
authors.forename: G T
authors.initials: GT
authors.lastname: Fosgate
mesh_terms: D000818:Animals; D002004:Brucella Vaccine / Q000008:administration & dosage*; D002003:Brucella abortus / Q000276:immunology* / Q000302:isolation & purification; D002006:Brucellosis / Q000276:immunology / Q000382:microbiology / Q000517:prevention & control / Q000662:veterinary*; D002020:Buffaloes / Q000033:anatomy & histology / Q000276:immunology* / Q000382:microbiology*; D005260:Female; D007111:Immunity, Cellular; D007115:Immunization Schedule; D066298:In Vitro Techniques; D007371:Interferon-gamma / Q000096:biosynthesis; D007963:Leukocytes, Mononuclear / Q000276:immunology; D008198:Lymph Nodes / Q000033:anatomy & histology / Q000276:immunology; D008297:Male
chemical_list: D002004:Brucella Vaccine; D007371:Interferon-gamma