Progress 07/01/06 to 06/30/09
Outputs
OUTPUTS: Neorickettsia risticii, an obligatory intracellular bacterium of the trematode and mammalian cells, causes Potomac horse fever (PHF) upon accidental ingestion of the infected trematode encysting the aquatic insects by horses. To facilitate our understanding of N. risticii and its pathogenesis, we determined the complete genome sequence of N. risticii Illinois. Analysis of the sequence revealed that the N. risticii genome consists of a single circular chromosome of 879,977 bp, and is predicted to encode 38 RNA species and 899 proteins. Although N. risticii has limited ability to synthesize amino acids and lacks many metabolic pathways, it is capable of making major vitamins, cofactors and nucleotides. Four-way comparison of genes among N. risticii and other Anaplasmataceae showed that most genes were either shared among all Anaplasmataceae (525 orthologs) that generally associated with housekeeping functions, or unique to each genome (>200 genes) that are mostly hypothetical proteins. Genes potentially involved in the pathogenesis of N. risticii were identified, including those encoding putative outer membrane proteins, two-component systems, and Type IV Secretion System (T4SS). The focal T4SS pilus protein VirB2 on bacterial surface was demonstrated for the first time for obligatory intracellular bacteria. These data provide insights toward fundamental biology of N. risticii and facilitate our understanding of PHF pathogenesis. PARTICIPANTS: Dr. Rikihisa is a professor in the Department of Veterinary Biosciences at Ohio State. TARGET AUDIENCES: Not relevant to this project. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
This is the first whole genome sequence work of N. risticii. The significance of the whole genome sequencing is that it provides a foundation for numerous genomic and proteomic comparisons and experiments. By comparing the type strain genome to other strains, genetic reasons for differences in virulence, mortality, and other differing factors can be determined. These identifications can lead to further experiments to determine functions of proteins or peptides within these proteins, which in turn can lead to the development of an effective treatment and vaccine for PHF.
Publications
- Lin, M., C. Zhang, K. Gibson, and Y. Rikihisa (2009) Analysis of Complete Genome Sequence of Neorickettsia risticii: the Causative Agent of Potomac Horse Fever. Nuc. Acid Res. 1-16
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Progress 01/01/08 to 12/31/08
Outputs
OUTPUTS: Neorickettsia risticii, an obligatory intracellular bacterium of the trematode and mammalian cells, causes Potomac horse fever (PHF) upon accidental ingestion of the infected trematode encysting the aquatic insects by horses. To facilitate our understanding of N. risticii and its pathogenesis, we determined the complete genome sequence of N. risticii Illinois. Analysis of the sequence revealed that the N. risticii genome consists of a single circular chromosome of 879,977 bp, and is predicted to encode 38 RNA species and 899 proteins. Although N. risticii has limited ability to synthesize amino acids and lacks many metabolic pathways, it is capable of making major vitamins, cofactors and nucleotides. Four-way comparison of genes among N. risticii and other Anaplasmataceae showed that most genes were either shared among all Anaplasmataceae (525 orthologs) that generally associated with housekeeping functions, or unique to each genome (>200 genes) that are mostly hypothetical proteins. Genes potentially involved in the pathogenesis of N. risticii were identified, including those encoding putative outer membrane proteins, two-component systems, and Type IV Secretion System (T4SS). The focal T4SS pilus protein VirB2 on bacterial surface was demonstrated for the first time for obligatory intracellular bacteria. These data provide insights toward fundamental biology of N. risticii and facilitate our understanding of PHF pathogenesis. PARTICIPANTS: Dr. Rikihisa is a Professor at The Ohio State University College of Veterinary Medicine. TARGET AUDIENCES: Not relevant to this project. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
This is the first whole genome sequence work of N. risticii. The significance of the whole genome sequencing is that it provides a foundation for numerous genomic and proteomic comparisons and experiments. By comparing the type strain genome to other strains, genetic reasons for differences in virulence, mortality, and other differing factors can be determined. These identifications can lead to further experiments to determine functions of proteins or peptides within these proteins, which in turn can lead to the development of an effective treatment and vaccine for PHF.
Publications
- Lin, M., C. Zhang, and Y. Rikihisa (2008) Complete genome sequencing of Neorickettsia risticii and comparison with other Anaplasmataceae. Abstract No. D-141. The 108th Annual Meeting of American Society for Microbiology, June 1-5, 2008. Boston, Mass. Poster presentation with published abstract.
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Progress 01/01/07 to 12/31/07
Outputs
Neorickettsia risticii is a small obligate intracellular, Gram-negative, polymorphic -proteobacterium that belongs to the family Anaplasmataceae. Maintained throughout the life cycle of a digenetic trematode, N. risticii causes Potomac horse fever (PHF) upon accidental ingestion of the infected trematode by horses. To facilitate our understanding of the virulence factors and protective surface antigens of N. risticii, we determined the complete genome sequence of N. risticii Illinois. Analysis of the sequence revealed that the N. risticii genome consists of a single circular chromosome of approximately 880 kbp, and is predicted to encode 38 RNA species and 899 proteins, 141 of which are distinct from those of a human pathogen, Neorickettsia sennetsu. The genome order is conserved between N. risticii with N. sennetsu, but is absent between N. risticii and other genera in Family Anaplasmataceae. Four-way comparison of genes among N. risticii and other
Anaplasmataceae showed that most genes were either shared among all Anaplasmataceae (525 orthologs) that generally associated with housekeeping functions, or unique to each genome (>200 orthologs) that are mostly hypothetical proteins. Like other Anaplasmataceae, N. risticii is capable of making major vitamins, cofactors and nucleotides, but has limited ability to synthesize amino acids. Further analysis identified genes potentially involved in the pathogenesis of N. risticii, including duplicated P51, tripricate SSA (P50/P85), several novel outer membrane proteins, genes encoding type IV secretion system including VirB2 which is not present in other genera of the family Anaplasmataceae, two-component systems, and transcriptional regulations. These data will provide insights toward fundamental biology of N. risticii and facilitate our understanding of pathogenesis of PHF.
Impacts
The significance of the whole genome sequencing is that it provides a foundation for numerous genomic and proteomic comparisons and experiments. By comparing the type strain genome to other strains, genetic reasons for differences in virulence, mortality, and other differing factors can be determined. These identifications can lead to further experiments to determine functions of proteins or peptides within these proteins, which in turn can lead to the development of an effective treatment and vaccine for PHF.
Publications
- No publications reported this period
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