A description of genes of Corynebacterium pseudotuberculosis useful in diagnostics and vaccine applications

Corynebacterium pseudotuberculosis, a Gram-positive intracellular pathogen, is the etiological agent of caseous lymphadenitis or CLA. This bacterium infects goats and sheep and causes great economic losses worldwide annually, mainly for goat producers. Despite its importance, CLA is still poorly characterized. However, with advances in the genomic field, many C. pseudotuberculosis genes have already been characterized, mainly those related to virulence such as phospholipase D. Here, we examined the use of the several available genes of C. pseudotuberculosis and reviewed their applications in vaccine construction, more efficient diagnostics for CLA, and control of this disease, among other applications.

Construction and partial characterization of a Corynebacterium pseudotuberculosis bacterial artificial chromosome library through genomic survey sequencing

Corynebacterium pseudotuberculosis is a gram-positive bacterium that causes caseous lymphadenitis in sheep and goats. However, despite the economic losses caused by caseous lymphadenitis, there is little information about the molecular mechanisms of pathogenesis of this bacterium. Genomic libraries constructed in bacterial artificial chromosome (BAC) vectors have become the method of choice for clone development in high-throughput genomic-sequencing projects. Large-insert DNA libraries are useful for isolation and characterization of important genomic regions and genes. In order to identify targets that might be useful for genome sequencing, we constructed a C. pseudotuberculosis BAC library in the vector pBeloBAC11. This library contains about 18,000 BAC clones, with inserts ranging in size from 25 to 120 kb, theoretically representing a 390-fold coverage of the C. pseudotuberculosis genome (estimated to be 2.5-3.1 Mb). Many genomic survey sequences (GSSs) with homology to C. diphtheriae, C. glutamicum, C. efficiens, and C. jeikeium proteins were observed within a sample of 215 sequenced clones, confirming their close phylogenetic relationship. Computer analyses of GSSs did not detect chimeric, deleted, or rearranged BAC clones, showing that this library has low redundancy. This GSSs collection is now available for further genetic and physical analysis of the C. pseudotuberculosis genome. The GSS strategy that we used to develop our library proved to be efficient for the identification of genes and will be an important tool for mapping, assembly, comparative, and functional genomic studies in a C. pseudotuberculosis genome sequencing project that will begin this year.

Update of microbial genome programs for bacteria and archaea

Since the Haemophilus influenzae genome sequence was completed in 1995, 172 other prokaryotic genomes have been completely sequenced, while 508 projects are underway. Besides pathogens, organisms important in several other fields, such as biotechnology and bioremediation, have also been sequenced. Institutions choose the organisms they wish to sequence according to the importance that these species represent to them, the availability of the microbes, and based on the similarity of a species of interest with others that have been sequenced previously. Improvements in sequencing techniques and in associated methodologies have been achieved; however, scientists need to continue working on the development of this field. In Brazil, a multicentered, centrally coordinated and research-focused network was adopted and successfully used for the sequencing of several important organisms. We analyzed the current status of microbial genomes, the trends for criteria used to choose new sequencing projects, the future of microbial sequencing, and the Brazilian genome network.