MLVA-16 typing of 295 marine mammal Brucella isolates from different animal and geographic origins identifies 7 major groups within Brucella ceti and Brucella pinnipedialis

Abstract

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.

Development, Validation, and Utilization of a Competitive Enzyme-Linked Immunosorbent Assay for the Detection of Antibodies against Brucella Species in Marine Mammals

“…23,37 The Brucella biovars isolated from marine mammals have microbiologic growth and genetic characteristics distinct from the classically recognized terrestrial species. 2,8,10,17,20,22,29,32,37 Genetic analyses of the various isolates from marine mammals indicate diversity from the terrestrial species, and there is strong evidence that shows that at least 2, if not more, species or biovars exist in marine mammals. New nomenclature for these marine species has been proposed but not officially accepted.…”

“…Multiple studies have detected anti-Brucella antibodies in marine mammals worldwide, from pinniped, cetacean, and mustelid families. 9,18,20,26,27,[31][32][33] Traditionally, a variety of serologic tests specifically designed and validated for Brucella abortus have been used to screen marine mammal sera for the presence of antibodies against the bacterium. Both the specificity and sensitivity of these tests for use with bovine serum are high; however, results of testing in marine mammals are often inconsistent, and comparisons between tests are difficult to make.…”

“…New nomenclature for these marine species has been proposed but not officially accepted. 2,8,12,14,20,38 Serology is an effective and efficient tool for screening animals for the presence of antibodies against Brucella spp., which indicate a current active infection or previous exposure. Multiple studies have detected anti-Brucella antibodies in marine mammals worldwide, from pinniped, cetacean, and mustelid families.…”

Age-dependent prevalence of anti-Brucella antibodies in hooded seals Cystophora cristata

“…The marine mammal Brucella spp. have shown variation in key aspects of virulence (Maquart et al 2009a); the ability to survive and multiply in macrophages (Gorvel & Moreno 2002), and different clusters within the B. ceti and B. pinnipedialis species have been recognized according to their preferred host, bacteriological properties and distinct genetic characteristics (What more et al 2007, Maquart et al 2009b, Guzmán-Verri et al 2012. There are indications that certain marine mammal Brucella spp.…”

Brucellosis in marine mammals, with special emphasis on the Republic of Croatia

“…It is believed that infections in whales may be transmitted sexually, or in contact with aborted off spring and placental tissue. Vertical transfer from mother to offspring is known [10][11][12]. In seals, the route of transmission is insufficiently known, though their communal lifestyle and constant direct contact between animals spurs the spread of infection.…”