Brucella spp. of amphibians comprise genomically diverse motile strains competent for replication in macrophages and survival in mammalian hosts

• Published in: Scientific Reports
• Main Authors: Al Dahouk, Sascha, Koehler, Stephan, Occhialini, Alessandra, Jimenez de Bagues, Maria Pilar, Hammerl, Jens Andre, Eisenberg, Tobias, Vergnaud, Gilles, Cloeckaert, Axel, Zygmunt, Michel S., Whatmore, Adrian M., Melzer, Falk, Drees, Kevin P., Foster, Jeffrey T., Wattam, Alice R., Scholz, Holger C.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Springer Nature 2017
• Subjects: bacterial bioinformatics database; vole microtus-arvalis; comparative sequence; genetic diversity; analysis resource; melitensis 16m; murine models; infection; lipopolysaccharide; death; Microtus arvalis
• Online Access: http://hdl.handle.net/10919/86649; https://doi.org/10.1038/srep44420

Twenty-one small Gram-negative motile coccobacilli were isolated from 15 systemically diseased African bullfrogs (Pyxicephalus edulis), and were initially identified as Ochrobactrum anthropi by standard microbiological identification systems. Phylogenetic reconstructions using combined molecular analyses and comparative whole genome analysis of the most diverse of the bullfrog strains verified affiliation with the genus Brucella and placed the isolates in a cluster containing B. inopinata and the other non-classical Brucella species but also revealed significant genetic differences within the group. Four representative but molecularly and phenotypically diverse strains were used for in vitro and in vivo infection experiments. All readily multiplied in macrophage-like murine J774-cells, and their overall intramacrophagic growth rate was comparable to that of B. inopinata BO1 and slightly higher than that of B. microti CCM 4915. In the BALB/c murine model of infection these strains replicated in both spleen and liver, but were less efficient than B. suis 1330. Some strains survived in the mammalian host for up to 12 weeks. The heterogeneity of these novel strains hampers a single species description but their phenotypic and genetic features suggest that they represent an evolutionary link between a soil-associated ancestor and the mammalian host-adapted pathogenic Brucella species. federal funds from National Institute of Allergy and Infectious Diseases; National Institutes of Health, Department of Health and Human Services [HHSN272201400027C]; Spanish grant [INIA-RTA2013-00065-C02-01]; Federal Institute for Risk Assessment, Germany [1329-485]; Food and Rural Affairs at German Federal Institute [SE0314, SE0316]; Department of Environment; Federal Ministry of Food and Agriculture [47-003, 1322-503, 1322-619]; Hessian Ministry of Environment, Climate Change, Agriculture and Consumer Protection; French DGA (Direction Generale de l'Armement) via the MicroType project [ANR-14-ASMA-0002-02]; European Defence Agency ...