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Genome sequence of Brucella abortus vaccine strain S19 compared to virulent strains yields candidate virulence genes.

ABSTRACT: The Brucella abortus strain S19, a spontaneously attenuated strain, has been used as a vaccine strain in vaccination of cattle against brucellosis for six decades. Despite many studies, the physiological and molecular mechanisms causing the attenuation are not known. We have applied pyrosequencing technology together with conventional sequencing to rapidly and comprehensively determine the complete genome sequence of the attenuated Brucella abortus vaccine strain S19. The main goal of this study is to identify candidate virulence genes by systematic comparative analysis of the attenuated strain with the published genome sequences of two virulent and closely related strains of B. abortus, 9-941 and 2308. The two S19 chromosomes are 2,122,487 and 1,161,449 bp in length. A total of 3062 genes were identified and annotated. Pairwise and reciprocal genome comparisons resulted in a total of 263 genes that were non-identical between the S19 genome and any of the two virulent strains. Amongst these, 45 genes were consistently different between the attenuated strain and the two virulent strains but were identical amongst the virulent strains, which included only two of the 236 genes that have been implicated as virulence factors in literature. The functional analyses of the differences have revealed a total of 24 genes that may be associated with the loss of virulence in S19. Of particular relevance are four genes with more than 60 bp consistent difference in S19 compared to both the virulent strains, which, in the virulent strains, encode an outer membrane protein and three proteins involved in erythritol uptake or metabolism.

SUBMITTER: Crasta OR

PROVIDER: S-EPMC2364660 | biostudies-literature | 2008 May

REPOSITORIES: biostudies-literature

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Genome sequence of Brucella abortus vaccine strain S19 compared to virulent strains yields candidate virulence genes.

Crasta Oswald R OR Folkerts Otto O Fei Zhangjun Z Mane Shrinivasrao P SP Evans Clive C Martino-Catt Susan S Bricker Betsy B Yu GongXin G Du Lei L Sobral Bruno W BW

PloS one 20080514 5

The Brucella abortus strain S19, a spontaneously attenuated strain, has been used as a vaccine strain in vaccination of cattle against brucellosis for six decades. Despite many studies, the physiological and molecular mechanisms causing the attenuation are not known. We have applied pyrosequencing technology together with conventional sequencing to rapidly and comprehensively determine the complete genome sequence of the attenuated Brucella abortus vaccine strain S19. The main goal of this study ...[more]

PMID: 18478107

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Project description:Goal: High-throughput sequencing-by-synthesis (Illumina) RNA sequencing technology was carried out with an aim to gain deeper understanding of immune host protective mechanisms. Here, RNA-seq was applied to understand the differential gene expression profile of mice spleen following immunization with Brucella abortus S19∆per mutant (perosamine synthetase gene mutant of Brucella abortus S19) in comparison to mock immunized mice spleen (PBS inoculated). Methods: RNA-seq data of 15th day post immunized mice spleen (with Brucella abortus S19∆per) and PBS control mice were generated by deep sequencing ( in duplicate) using IlluminaNextSeq 500 . The sequence reads that passed quality filters were analyzed for transcript abundance using RSEM package (RNA-Seq by Expectation Maximization) (Li and Dewey, 2011). Breifly, the RSEM package generated a reference sequence based on given mouse transcript annotations (Mus_musculus.GrCm38.83.chr.gtf.gz). The Bowtie allignmet tool available within the package was used to calculate expected counts (number of mapped reads) using quality trimmed reads and reference sequence. Finally, the expected counts estimated by RSEM were fed into different DE package tools, such as DESeq2 (Love et al., 2014), edgeR (Robinson et al., 2010) and EBSeq (Leng et al., 2013) in order to identify differentially expressed genes across spleen samples (B. abortus S19∆per versus (vs) PBS control. Functional annotation of differently expressed genes were carried out using g:Profiler (Reimandet al., 2016; http://biit.cs.ut.ee/gprofiler/). Results: A mean of 37.58 million processed reads (range: 30.51 million to 51.79 million reads per individual RNA-seq library) were generated during the experiment. The expected counts generated by the RSEM package followed by differential analysis calculation using different DE packages identified a total of 1917 differentially expressed genes (DEGs), of which 968 and 949 genes were up- and down-regulated respectively. Functional annotation revealed 545 significantly enriched genes to be associated with immune system processes within the total 1917 differentially expressed genes. Further analysis revealed 21 genes showing significant expression were also in MHC-I and MHC-II antigen processing and presentation pathway during S19∆per immunization. Conclusions:The RNA-seq data revealed the coordinated up-regulation of MHC-I and MHC-II processing pathways providing insights into the molecular mechanism of immune protection conferred by B. abortus S19∆per in mice at day 15 post immunization and might aid in the development of new attenuated vaccine strains with improved efficacy.

Dataset Information

Genome sequence of Brucella abortus vaccine strain S19 compared to virulent strains yields candidate virulence genes.

Publications

Genome sequence of Brucella abortus vaccine strain S19 compared to virulent strains yields candidate virulence genes.

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