title: Genomic Changes Associated with the Loss of Nocardia brasiliensis Virulence in Mice after 200 In Vitro Passages.
abstract: Nocardia species, particularly Nocardia brasiliensis, are etiologic agents of mycetoma, a chronic subcutaneous infection. Until now, little has been known about the pathogenic mechanisms involved in nocardial infection. Traditionally, subculture in rich media has been a simple way to induce attenuation. In this work, we report the changes in virulence toward mice and in genomic constitution of N. brasiliensis produced after 200 continuous subcultures in brain heart infusion (BHI) medium (P-200 strain). The ability of the N. brasiliensis P-200 strain to produce experimental infection was tested using BALB/c mice. P-200 was also used to immunize mice to determine whether it could induce resistance against a challenge with a nonsubcultured isolate (P-0). Comparative proteomic analysis between N. brasiliensis P-0 and P-200 was performed by two-dimensional (2-D) electrophoresis, and the genome sequence was obtained through Roche 454 sequence analysis. Virulence in BALB/c mice was completely lost, and BALB/c mice immunized with P-200 bacterial cells were resistant to mycetoma production by the nonsubcultured strain. Whole-genome sequence analysis revealed that P-200 lost a total of 262,913 bp distributed in 19 deleted regions, involving a total of 213 open reading frames (ORFs). The deleted genes included those encoding bacterial virulence factors, e.g., catalase, nitrate reductase enzymes, and a group of mammalian cell entry (MCE) family proteins, which may explain the loss of virulence of the isolate. Thus, completely attenuated N. brasiliensis was obtained after 200 passages in BHI medium, and putative Nocardia virulence genes were identified for the first time.
authors.affiliation: Laboratorio Interdisciplinario de Investigación Dermatológica, Servicio de Dermatología, Hospital Universitario, U.A.N.L., Monterrey, Mexico.
authors.forename: Carolina
authors.initials: C
authors.lastname: Gonzalez-Carrillo
authors.affiliation: Laboratorio Interdisciplinario de Investigación Dermatológica, Servicio de Dermatología, Hospital Universitario, U.A.N.L., Monterrey, Mexico.
authors.forename: Cassandra
authors.initials: C
authors.lastname: Millan-Sauceda
authors.affiliation: Laboratorio Interdisciplinario de Investigación Dermatológica, Servicio de Dermatología, Hospital Universitario, U.A.N.L., Monterrey, Mexico.
authors.forename: Hector Gerardo
authors.initials: HG
authors.lastname: Lozano-Garza
authors.affiliation: Universidad Autónoma de Nuevo León, Departmento de Bioquímica y Medicina Molecular, Monterrey, Mexico Universidad Autónoma de Nuevo León, Centro de Investigación y Desarrollo en Ciencias de la Salud, Monterrey, Mexico.
authors.forename: Rocio
authors.initials: R
authors.lastname: Ortiz-Lopez
authors.affiliation: Universidad Autónoma de Nuevo León, Centro de Investigación y Desarrollo en Ciencias de la Salud, Monterrey, Mexico.
authors.forename: Ramiro
authors.initials: R
authors.lastname: Elizondo-Gonzalez
authors.affiliation: Laboratorio Interdisciplinario de Investigación Dermatológica, Servicio de Dermatología, Hospital Universitario, U.A.N.L., Monterrey, Mexico.
authors.forename: Oliverio
authors.initials: O
authors.lastname: Welsh
authors.affiliation: Laboratorio Interdisciplinario de Investigación Dermatológica, Servicio de Dermatología, Hospital Universitario, U.A.N.L., Monterrey, Mexico.
authors.forename: Jorge
authors.initials: J
authors.lastname: Ocampo-Candiani
authors.affiliation: Laboratorio Interdisciplinario de Investigación Dermatológica, Servicio de Dermatología, Hospital Universitario, U.A.N.L., Monterrey, Mexico luvera_99@yahoo.com.
authors.forename: Lucio
authors.initials: L
authors.lastname: Vera-Cabrera
mesh_terms: D000818:Animals; D005260:Female; D023281:Genomics / Q000379:methods; D051379:Mice; D008807:Mice, Inbred BALB C; D008271:Mycetoma / Q000382:microbiology; D009615:Nocardia / Q000235:genetics* / Q000472:pathogenicity*; D009617:Nocardia Infections / Q000382:microbiology*; D040901:Proteomics / Q000379:methods; D014774:Virulence / Q000235:genetics*; D037521:Virulence Factors / Q000235:genetics*
chemical_list: D037521:Virulence Factors