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Marine Mammal Brucella Reference Strains Are Attenuated in a BALB/c Mouse Model.

ABSTRACT: Brucellosis is a zoonosis of worldwide distribution with numerous animal host species. Since the novel isolation of Brucella spp. from marine mammals in 1994 the bacteria have been isolated from various marine mammal hosts. The marine mammal reference strains Brucella pinnipedialis 12890 (harbour seal, Phoca vitulina) and Brucella ceti 12891 (harbour porpoise, Phocoena phocoena) were included in genus Brucella in 2007, however, their pathogenicity in the mouse model is pending. Herein this is evaluated in BALB/c mice with Brucella suis 1330 as a control. Both marine mammal strains were attenuated, however, B. ceti was present at higher levels than B. pinnipedialis in blood, spleen and liver throughout the infection, in addition B. suis and B. ceti were isolated from brains and faeces at times with high levels of bacteraemia. In B. suis-infected mice serum cytokines peaked at day 7. In B. pinnipedialis-infected mice, levels were similar, but peaked predominantly at day 3 and an earlier peak in spleen weight likewise implied an earlier response. The inflammatory response induced pathology in the spleen and liver. In B. ceti-infected mice, most serum cytokine levels were comparable to those in uninfected mice, consistent with a limited inflammatory response, which also was indicated by restricted spleen and liver pathology. Specific immune responses against all three strains were detected in vitro after stimulation of splenocytes from infected mice with the homologous heat-killed brucellae. Antibody responses in vivo were also induced by the three brucellae. The immunological pattern of B. ceti in combination with persistence in organs and limited pathology has heretofore not been described for other brucellae. These two marine mammal wildtype strains show an attenuated pattern in BALB/c mice only previously described for Brucella neotomea.

SUBMITTER: Nymo IH

PROVIDER: S-EPMC4784796 | biostudies-literature | 2016

REPOSITORIES: biostudies-literature

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Marine Mammal Brucella Reference Strains Are Attenuated in a BALB/c Mouse Model.

Nymo Ingebjørg H IH Arias Maykel A MA Pardo Julián J Álvarez María Pilar MP Alcaraz Ana A Godfroid Jacques J Jiménez de Bagüés María Pilar MP

PloS one 20160309 3

Brucellosis is a zoonosis of worldwide distribution with numerous animal host species. Since the novel isolation of Brucella spp. from marine mammals in 1994 the bacteria have been isolated from various marine mammal hosts. The marine mammal reference strains Brucella pinnipedialis 12890 (harbour seal, Phoca vitulina) and Brucella ceti 12891 (harbour porpoise, Phocoena phocoena) were included in genus Brucella in 2007, however, their pathogenicity in the mouse model is pending. Herein this is ev ...[more]

PMID: 26959235

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Project description:BackgroundSince 1994, Brucella strains have been isolated from a wide range of marine mammals. They are currently recognized as two new Brucella species, B. pinnipedialis for the pinniped isolates and B. ceti for the cetacean isolates in agreement with host preference and specific phenotypic and molecular markers. In order to investigate the genetic relationships within the marine mammal Brucella isolates and with reference to terrestrial mammal Brucella isolates, we applied in this study the Multiple Loci VNTR (Variable Number of Tandem Repeats) Analysis (MLVA) approach. A previously published assay comprising 16 loci (MLVA-16) that has been shown to be highly relevant and efficient for typing and clustering Brucella strains from animal and human origin was used.Results294 marine mammal Brucella strains collected in European waters from 173 animals and a human isolate from New Zealand presumably from marine origin were investigated by MLVA-16. Marine mammal Brucella isolates were shown to be different from the recognized terrestrial mammal Brucella species and biovars and corresponded to 3 major related groups, one specific of the B. ceti strains, one of the B. pinnipedialis strains and the last composed of the human isolate. In the B. ceti group, 3 subclusters were identified, distinguishing a cluster of dolphin, minke whale and porpoise isolates and two clusters mostly composed of dolphin isolates. These results were in accordance with published analyses using other phenotypic or molecular approaches, or different panels of VNTR loci. The B. pinnipedialis group could be similarly subdivided in 3 subclusters, one composed exclusively of isolates from hooded seals (Cystophora cristata) and the two others comprising other seal species isolates.ConclusionThe clustering analysis of a large collection of marine mammal Brucella isolates from European waters significantly strengthens the current view of the population structure of these two species, and their relative position with respect to the rest of the Brucella genus. MLVA-16 is confirmed as being a rapid, highly discriminatory and reproducible method to classify Brucella strains including the marine mammal isolates. The Brucella2009 MLVA-16 genotyping database available at http://mlva.u-psud.fr/ is providing a detailed coverage of all 9 currently recognized Brucella species.

Project description:A high prevalence of Brucellapinnipedialis serology and bacteriology positive animals has been found in the Northeast Atlantic stock of hooded seal (Cystophoracristata); however no associated gross pathological changes have been identified. Marine mammal brucellae have previously displayed different infection patterns in human and murine macrophages. To investigate if marine mammal Brucella spp. are able to invade and multiply in cells originating from a presumed host species, we infected alveolar macrophages from hooded seal with a B. pinnipedialis hooded seal isolate. Hooded seal alveolar macrophages were also challenged with B. pinnipedialis reference strain (NCTC 12890) from harbor seal (Phocavitulina), B. ceti reference strain (NCTC 12891) from harbor porpoise (Phocoenaphocoena) and a B. ceti Atlantic white-sided dolphin (Lagenorhynchusacutus) isolate (M83/07/1), to evaluate possible species-specific differences. Brucella suis 1330 was included as a positive control. Alveolar macrophages were obtained by post mortem bronchoalveolar lavage of euthanized hooded seals. Phenotyping of cells in the lavage fluid was executed by flow cytometry using the surface markers CD14 and CD18. Cultured lavage cells were identified as alveolar macrophages based on morphology, expression of surface markers and phagocytic ability. Alveolar macrophages were challenged with Brucella spp. in a gentamicin protection assay. Following infection, cell lysates from different time points were plated and evaluated quantitatively for colony forming units. Intracellular presence of B. pinnipedialis hooded seal isolate was verified by immunocytochemistry. Our results show that the marine mammal brucellae were able to enter hooded seal alveolar macrophages; however, they did not multiply intracellularly and were eliminated within 48 hours, to the contrary of B. suis that showed the classical pattern of a pathogenic strain. In conclusion, none of the four marine mammal strains tested were able to establish a persistent infection in primary alveolar macrophages from hooded seal.

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Marine Mammal Brucella Reference Strains Are Attenuated in a BALB/c Mouse Model.

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Marine Mammal Brucella Reference Strains Are Attenuated in a BALB/c Mouse Model.

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