Project description:BACKGROUND: Riemerella anatipestifer is one of the most important pathogens of ducks. However, the molecular mechanisms of R. anatipestifer infection are poorly understood. In particular, the lack of genomic information from a variety of R. anatipestifer strains has proved severely limiting. RESULTS: In this study, we present the complete genomes of two R. anatipestifer strains, RA-CH-1 (2,309,519 bp, Genbank accession CP003787) and RA-CH-2 (2,166,321 bp, Genbank accession CP004020). Both strains are from isolates taken from two different sick ducks in the SiChuang province of China. A comparative genomics approach was used to identify similarities and key differences between RA-CH-1 and RA-CH-2 and the previously sequenced strain RA-GD, a clinical isolate from GuangDong, China, and ATCC11845. CONCLUSION: The genomes of RA-CH-2 and RA-GD were extremely similar, while RA-CH-1 was significantly different than ATCC11845. RA-CH-1 is 140,000 bp larger than the three other strains and has 16 unique gene families. Evolutionary analysis shows that RA-CH-1 and RA-CH-2 are closed and in a branch with ATCC11845, while RA-GD is located in another branch. Additionally, the detection of several iron/heme-transport related proteins and motility mechanisms will be useful in elucidating factors important in pathogenicity. This information will allow a better understanding of the phenotype of different R. anatipestifer strains and molecular mechanisms of infection.
Project description:Riemerella anatipestifer is an infectious pathogen causing serositis in ducks. We had the genome of the R. anatipestifer reference strain ATCC 11845 sequenced. The completed draft genome consists of one circular chromosome with 2,164,087 bp. There are 2,101 genes in the draft, and its GC content is 35.01%.
Project description:Riemerella anatipestifer is a Gram-negative bacterium belonging to the family Flavobacteriaceae It is primarily associated with acute septicemia in younger birds. The R. anatipestifer isolate 17CS0503 described here was isolated from a Peking duck (Anas platyrhynchos domesticus) in Hannover, Germany, in 1999.
Project description:Riemerella anatipestifer is an important bacterial pathogen associated with epizootic infections in waterfowl and various other birds. The complete genome sequence of Riemerella anatipestifer xi1, isolated in China, was sequenced. The genome consisted of 2,062,911 bp carrying 1,879 predicted genes.
Project description:BackgroundRiemerella anatipestifer (R. anatipestifer) is one of the most important poultry pathogens worldwide, with associated infections causing significant economic losses. Rifampin Resistance is an important mechanism of drug resistance. However, there is no information about rpoB mutations conferring rifampin resistance and its fitness cost in Riemerella anatipestifer.ResultsComparative analysis of 18 R.anatipestifer rpoB sequences and the determination of rifampin minimum inhibitory concentrations showed that five point mutations, V382I, H491N, G502K, R494K and S539Y, were related to rifampin resistance. Five overexpression strains were constructed using site-directed mutagenesis to validate these sites. To investigate the origin and fitness costs of the rpoB mutations, 15 types of rpoB mutations were isolated from R. anatipestifer ATCC 11845 by using spontaneous mutation in which R494K was identical to the type of mutation detected in the isolates. The mutation frequency of the rpoB gene was calculated to be 10- 8. A total of 98.8% (247/250) of the obtained mutants were located in cluster I of the rifampin resistance-determining region of the rpoB gene. With the exception of D481Y, I537N and S539F, the rifampin minimum inhibitory concentrations of the remaining mutants were at least 64 μg/mL. The growth performance and competitive experiments of the mutant strains in vitro showed that H491D and 485::TAA exhibit growth delay and severely impaired fitness. Finally, the colonization abilities and sensitivities of the R494K and H491D mutants were investigated. The sensitivity of the two mutants to hydrogen peroxide (H2O2) and sodium nitroprusside (SNP) increased compared to the parental strain. The number of live colonies colonized by the two mutants in the duckling brain and trachea were lower than that of the parental strain within 24 h.ConclusionsMutations of rpoB gene in R. anatipestifer mediate rifampin resistance and result in fitness costs. And different single mutations confer different levels of fitness costs. Our study provides, to our knowledge, the first estimates of the fitness cost associated with the R. anatipestifer rifampin resistance in vitro and in vivo.
Project description:Riemerella anatipestifer is a pathogenic bacterium that has spread all over the world and is associated with epizootic infections in waterfowl and other avian species. R. anatipestifer RA-SG is an avirulent strain, isolated from an infected duck in Guangdong province, China. The genome sequence of this species is presented herein.
Project description:The outbreak of Riemerella anatipestifer (RA) infection has been confirmed in meat-type domestic ducks (Anas platyrhynchos) for the first time in 27 years in Japan. In January 2014, increased mortality in a 14- to 21-day-old duck flock was reported to veterinary officials by the owner. The affected ducks exhibited reduced movement, ataxia and dorsal recumbency with leg paddling. Pathological findings were typical for an RA infection. Fibrinous and heterophilic pericarditis, airsacculitis, perihepatitis, ventriculitis and meningitis were observed. The bacterial isolate from duck organs was identified as RA by PCR-based 16S ribosomal RNA sequencing.
Project description:Riemerella anatipestifer (Hendrickson and Hilbert 1932) Segers et al. 1993 is the type species of the genus Riemerella, which belongs to the family Flavobacteriaceae. The species is of interest because of the position of the genus in the phylogenetic tree and because of its role as a pathogen of commercially important avian species worldwide. This is the first completed genome sequence of a member of the genus Riemerella. The 2,155,121 bp long genome with its 2,001 protein-coding and 51 RNA genes consists of one circular chromosome and is a part of the Genomic Encyclopedia of Bacteria and Archaea project.
Project description:The complete genome sequence of highly virulent Riemerella anatipestifer strain HXb2 was determined. The genome consisted of a single circular chromosome of 2,425,237 bp containing 2,383 putative open reading frames (ORFs), 9 rRNA operons, and 40 tRNA genes.
Project description:Riemerella anatipestifer infection causes serious economic losses in the duck industry worldwide. Acute septicemia and high blood bacterial loading in R. anatipestifer infected ducks indicate that R. anatipestifer may be able to obtain iron and other nutrients by lysing duck erythrocytes to support its rapid growth and proliferation in the blood. However, so far, little is known about the hemolytic activity of R. anatipestifer to duck erythrocytes. In this study, 29 of 52 R. anatipestifer strains showed hemolytic activity on duck blood agar, whereas all the tested dba+ (with hemolytic activity on duck blood agar) and dba- strains created pores in the duck red blood cells, with 4.35-9.03% hemolytic activity in a liquid hemolysis assay after incubation for 24 h. The concentrated culture supernatants of all the tested R. anatipestifer strains and the extracted outer membrane proteins (OMPs) from dba+ R. anatipestifer strains showed hemolytic activity on duck blood agar. These results, together with the median lethal dose (LD50) of some dba+ and dba- R. anatipestifer strains in ducklings, suggested that there was no direct relationship between the hemolytic capacity of R. anatipestifer on duck blood agar and its virulence.