This Article Full Text Full Text (PDF) Supplemental material Other Versions of this Article: IAI.00952-06v1 75/1/299    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Delpino, M. V. Articles by Baldi, P. C. Search for Related Content PubMed PubMed Citation Articles by Delpino, M. V. Articles by Baldi, P. C.

A Bile Salt Hydrolase of Brucella abortus Contributes to the Establishment of a Successful Infection through the Oral Route in Mice ^,

Instituto de Estudios de la Inmunidad Humoral (IDEHU, CONICET-UBA), Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, 1113 Buenos Aires, Argentina,¹ Instituto de Investigaciones Biotecnológicas, Universidad Nacional de Gral. San Martín, 1650 San Martín, Argentina,² Laboratorio de Inmunología, Departamento de Sanidad Animal y Medicina Preventiva, Facultad de Ciencias Veterinarias, Universidad Nacional del Centro de la Provincia de Buenos Aires, 7000 Tandil, Argentina,³ Laboratorio de Inmunogenética, Hospital de Clínicas "José de San Martín," Facultad de Medicina, Universidad de Buenos Aires, 1120 Buenos Aires, Argentina⁴

Received 14 June 2006/ Returned for modification 25 July 2006/ Accepted 23 October 2006

Choloylglycine hydrolase (CGH), a bile salt hydrolase, has been annotated in all the available genomes of Brucella species. We obtained the Brucella CGH in recombinant form and demonstrated in vitro its capacity to cleave glycocholate into glycine and cholate. Brucella abortus 2308 (wild type) and its isogenic cgh deletion mutant exhibited similar growth rates in tryptic soy broth in the absence of bile. In contrast, the growth of the cgh mutant was notably impaired by both 5% and 10% bile. The bile resistance of the complemented mutant was similar to that of the wild-type strain. In mice infected through the intragastric or the intraperitoneal route, splenic infection was significantly lower at 10 and 20 days postinfection in animals infected with the cgh mutant than in those infected with the wild-type strain. For both routes, no differences in spleen CFU were found between animals infected with the wild-type strain and those infected with the complemented mutant. Mice immunized intragastrically with recombinant CGH mixed with cholera toxin (CGH+CT) developed a specific mucosal humoral (immunoglobulin G [IgG] and IgA) and cellular (interleukin-2) immune responses. Fifteen days after challenge by the same route with live B. abortus 2308 cells, splenic CFU counts were 10-fold lower in mice immunized with CGH+CT than in mice immunized with CT or phosphate-buffered saline. This study shows that CGH confers on Brucella the ability to resist the antimicrobial action of bile salts. The results also suggest that CGH may contribute to the ability of Brucella to infect the host through the oral route.

Published ahead of print on 6 November 2006.

Editor: D. L. Burns

Supplemental material for this article may be found at http://iai.asm.org/.