Identification of a Novel Small Non-Coding RNA Modulating the Intracellular Survival of Brucella melitensis.

Bacterial small non-coding RNAs (sRNAs) are gene expression modulators respond to environmental changes, stressful conditions, and pathogenesis. In this study, by using a combined bioinformatic and experimental approach, eight novel sRNA genes were identified in intracellular pathogen Brucella melitensis. BSR0602, one sRNA that was highly induced in stationary phase, was further examined and found to modulate the intracellular survival of B. melitensis. BSR0602 was present at very high levels in vitro under stresses similar to those encountered during infection in host macrophages. Furthermore, BSR0602 was found to be highly expressed in the spleens of infected mice, suggesting its potential role in the control of pathogenesis. BSR0602 targets the mRNAs coding for gntR, a global transcriptional regulator, which is required for B. melitensis virulence. Overexpression of BSR0602 results in distinct reduction in the gntR mRNA level. B. melitensis with high level of BSR0602 is defective in bacteria intracellular survival in macrophages and defective in growth in the spleens of infected mice. Therefore, BSR0602 may directly inhibit the expression of gntR, which then impairs Brucellae intracellular survival and contributes to Brucella infection. Our findings suggest that BSR0602 is responsible for bacterial adaptation to stress conditions and thus modulate B. melitensis intracellular survival.

Changes of predominant species/biovars and sequence types of Brucella isolates, Inner Mongolia, China.

BACKGROUND: Human brucellosis incidence in China was divided into 3 stages, high incidence (1950-1960s), decline (1970-1980s) and re-emergence (1990-2000s). Human brucellosis has been reported in all the 32 provinces, of which Inner Mongolia has the highest prevalence, accounting for over 40% of the cases in China. To investigate the etiology alteration of human brucellosis in Inner Mongolia, the species, biovars and genotypes of 60 Brucella isolates from this province were analyzed. METHODS: Species and biovars of the Brucella strains isolated from outbreaks were determined based on classical identification procedures. Strains were genotyped by multi locus sequence typing (MLST). Sequences of 9 housekeeping genes were obtained and sequence types were defined. The distribution of species, biovars and sequence types (STs) among the three incidence stages were analyzed and compared. RESULTS: The three stages of high incidence, decline and re-emergence were predominated by B. melitensis biovar 2 and 3, B. abortus biovar 3, and B. melitensis biovar 1, respectively, implying changes in the predominant biovars. Genotyping by MLST revealed a total of 14 STs. Nine STs (from ST28 to ST36), accounting for 64.3% of all the STs, were newly defined and different from those observed in other countries. Different STs were distributed among the three stages. ST8 was the most common ST in 1950-1960s and 1990-2000s, while ST2 was the most common in 1970-1980s. CONCLUSIONS: The prevalence of biovars and sequence types of Brucella strains from Inner Mongolia has changed over time in the three stages. Compared with those from other countries, new sequence types of Brucella strains exist in China.

Impact of Hfq on global gene expression and intracellular survival in Brucella melitensis.

Brucella melitensis is a facultative intracellular bacterium that replicates within macrophages. The ability of brucellae to survive and multiply in the hostile environment of host macrophages is essential to its virulence. The RNA-binding protein Hfq is a global regulator that is involved in stress resistance and pathogenicity. Here we demonstrate that Hfq is essential for stress adaptation and intracellular survival in B. melitensis. A B. melitensis hfq deletion mutant exhibits reduced survival under environmental stresses and is attenuated in cultured macrophages and mice. Microarray-based transcriptome analyses revealed that 359 genes involved in numerous cellular processes were dysregulated in the hfq mutant. From these same samples the proteins were also prepared for proteomic analysis to directly identify Hfq-regulated proteins. Fifty-five proteins with significantly affected expression were identified in the hfq mutant. Our results demonstrate that Hfq regulates many genes and/or proteins involved in metabolism, virulence, and stress responses, including those potentially involved in the adaptation of Brucella to the oxidative, acid, heat stress, and antibacterial peptides encountered within the host. The dysregulation of such genes and/or proteins could contribute to the attenuated hfq mutant phenotype. These findings highlight the involvement of Hfq as a key regulator of Brucella gene expression and facilitate our understanding of the role of Hfq in environmental stress adaptation and intracellular survival of B. melitensis.

Complete genome sequence of Brucella melitensis 133, an isolate of biovar 1 of sequence type 32.

Brucellosis is highly epidemic in China. Of the six classical species, Brucella melitensis and biovar 1 are the most represented species and biovar that cause human brucellosis in China. Here, we report the genome sequence of Brucella melitensis strain 133, a strain of biovar 1 of sequence type 32.

Complete genome sequence of Brucella abortus strain BCB034, a strain of biovar 2 isolated from human.

Brucella abortus is divided into eight biovars, of which biovars 1 to 3 are the most frequently represented biovars in strains isolated from humans. Here, we report the genome sequence of B. abortus strain BCB034, a strain isolated from a human patient and that belongs to biovar 2.

Complete genome sequence of Brucella suis field strain BCB025 of sequence type ST22.

Brucella is a genus of relatively conservative pathogenic bacteria. Brucella suis is the most diversified Brucella species. Strains of B. suis belong to different sequence types. Here, we report the genome sequence of B. suis strain BCB025, one isolate of the sequence type 22 epidemic in China.

Genome sequence of Brucella melitensis strain 128, an isolate of biovar 3 of sequence type 8.

Brucella melitensis is the most common Brucella species causing human brucellosis. B. melitensis is divided into 3 biovars. Here, we report the complete genome sequence of B. melitensis strain 128, a strain of biovar 3 of sequence type 8, which is prevalent in China.

Complete genome sequence of Brucella abortus 134, a biovar 1 strain isolated from human.

Brucella abortus is one of the common pathogens causing brucellosis in China. Here, we report the genome sequence of B. abortus strain 134, a strain isolated from a human patient and belonging to biovar 1, the most highly represented biovar among B. abortus strains in China.

Complete genome sequence of Brucella canis strain 118, a strain isolated from canine.

Brucella canis infects several species of animals, and canine is the preferred host. Genome sequences of strains from different hosts are valuable for comparative analysis of host adaptation and microevolution. Here, we report the genome sequence of Brucella canis strain 118, a strain isolated from canine.

Genome sequence of Stenotrophomonas maltophilia S028, an isolate harboring the AmpR-L2 resistance module.

Multidrug-resistant Stenotrophomonas maltophilia has emerged as an important cause of nosocomial infections, which is attributable mainly to the production of diverse ß-lactamases by S. maltophilia. The L2 ß-lactamase mediated by the AmpR-L2 module is the most represented lactamase. Here, we announce the genome sequence of S028, an isolate harboring the AmpR-L2 module.

Complete genome sequence of Brucella canis BCB018, a strain isolated from a human patient.

Brucella canis is considered a rare cause of human brucellosis because of difficulties in presumptive diagnosis and underestimation of the incidence. Here, we report the draft genome sequence of a Brucella canis isolate, BCB018, isolated from a human patient, providing precious resources for comparative genomics analysis of Brucella field strains.

Genome sequence of an OXA23-producing, carbapenem-resistant Acinetobacter baumannii strain of sequence type ST75.

The increase of Acinetobacter baumannii resistance to carbapenems is of great concern. OXA23 is one of the most prevalent carbapenemases of A. baumannii that causes outbreaks. Here, we announce the genome sequence of an OXA23-producing A. baumannii strain assigned ST75, a newly emerged sequence type harboring carbapenemase.

Genome sequences of three live attenuated vaccine strains of Brucella species and implications for pathogenesis and differential diagnosis.

Live attenuated vaccines play essential roles in the prevention of brucellosis. Here, we report the draft genome sequences of three vaccine strains, Brucella melitensis M5-10, B. suis S2-30, and B. abortus 104M. Primary genome sequence analysis identified mutations, deletions, and insertions which have implications for attenuation and signatures for differential diagnosis.

Genome sequence of Brucella melitensis S66, an isolate of sequence type 8, prevalent in China.

Brucella melitensis is the most-represented Brucella species causing human brucellosis in China. Here we report the complete genome sequence of B. melitensis strain S66, a representative strain of sequence type 8 (ST8), which is prevalent in China, making it possible to compare the genome sequences of isolates from different countries.

Genome sequences of Brucella melitensis 16M and its two derivatives 16M1w and 16M13w, which evolved in vivo.

Brucella melitensis is an intracellular pathogen that induces chronic infection in humans. Here, we report the genome sequences of 16M and its two derivatives, 16M1w and 16M13w, which were allowed to adapt in vivo for 1 and 13 weeks, respectively. Our findings contribute to the investigation of adaptive mutations and mechanisms of chronic infection by B. melitensis.