Mycoplasma hyorhinis Project Description



Brief Summary

The purpose of this project is to determine and annotate the genomic DNA sequence of Mycoplasma hyorhinis. Mycoplasma hyorhinis was first isolated from the respiratory tract of young pigs, and has been implicated in pleuritis, peritonitis, pericarditis, arthritis and otitis media of swine. The interest in M. hyorhinis has recently increased after the detection of this organism in human beings.. Another important proclivity of M. hyorhinis is its special effectiveness in contaminating cell cultures which impinges on many aspects of biological research. The specific objectives are to identify possible pathogenic factors of M. hyorhinis efficiently by comparative genomics.

The project is organized under the direction of Steve Goodison, Department of Surgery, University of Florida College of Medicine. Strain SK76 is the type strain of the organism and its taxonomic status and pathogenicity have been extensively characterized at the University of Missouri School of Medicine, Columbia, Missouri. DNA sequencing, bioinformatics tools, and website design are performed in partnership with the University of Florida ICBR Genomics Core, directed by William Farmerie

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About the Organism

Superkingdom:: Eubacteria;
Phylum: Firmicutes;
Class: Mollicutes;
Order: Mycoplasmatales;
Family: Mycoplasmataceae.

Taxonomy ID:: 2100
Rank: species
Genetic Code: Translation table 4 (Mold Mitochondrial; Protozoan Mitochondrial; Coelenterate Mitochondrial; Mycoplasma; Spiroplasma)
Other Names:

What is Mycoplasma hyorhinis?

Multiple sequence alignments with other mollicutes indicated that M. flocculare, M. hyopneumoniae, and Mycoplasma hyorhinis form a subcluster within the fermentans phylogroup, and this subcluster is distinct from the Mycoplasma pneumoniae phylogroup. Thus, the three mycoplasmas isolated from porcine respiratory systems exhibit phylogenetic similarities (Stemke, G.W., Laigret, F., Grau, O., and Bove, J.M. "Phylogenetic relationships of three porcine mycoplasmas, Mycoplasma hyopneumoniae, Mycoplasma flocculare, and Mycoplasma hyorhinis, and complete 16S rRNA sequence of M. flocculare." Int. J. Syst. Bacteriol. (1992) 42:220-225)

Mycoplasma hyopneumoniae is the etiological agent of enzootic pneumonia of swine, a chronic non-fatal disease resulting in poor food conversion, retarded growth and predisposition to bacterial pneumonia. The disease is spread worldwide and causes large economic losses in swine production. Transmission occurs through direct contact with respiratory secretions from carrier animals and via sow-to-piglet transmission. Serological investigations showed that up to 25% of pigs contain antibodies to M. hyopneumoniae at age 10-12 weeks and that at time of slaughter approximately 90% of animals are seropositive. Methods developed for the detection of M. hyopneumoniae infections have been based mainly on whole cell or membrane preparations and gene fragments. These include culture of M. hyopneumoniae from pig lungs, immunofluorescence assay, DNA probes, ELISA and PCR. However, most of these methods lack specificity due to cross-reactions with the closely related swine mycoplasmas, Mycoplasma flocculare and Mycoplasma hyorhinis, thus specific sequence for M. hyorhinis may aid detection and distinction between swine mycoplasmal infections.

A study of the pathology of the porcine ear was performed on 479 pigs ranging in age from 1 day to 1 year. Histologically, 364 (76.0%) of 479 pigs were affected with otitis. Eustachitis was the most common and preceded an inflammation of other sites of the ear, and an acute eustachitis occurred from as early as 1 week of life. Immunohistochemical examination of frozen cryostat sections revealed Mycoplasma hyorhinis (Mhr) antigens on the luminal surface of the eustachian epithelia in 14 (50.0%) of 28 piglets examined. All the pigs positive for Mhr had an acute eustachitis. Ultrastructural examination on the auditory tubes with positive immunostaining disclosed many mycoplasmas among the cilia. Mhr was isolated from the auditory tubes and tympanic cavities of 19 (67.9%) and 16 (57.1%) of 28 piglets examined, respectively. (Morita T, Ohiwa S, Shimada A, Kazama S, Yagihashi T, Umemura T.Intranasally inoculated Mycoplasma hyorhinis causes eustachitis in pigs. Vet Pathol. 1999 Mar;36(2):174-8.) M. hyorhinis has also been linked to abortion in pigs. A virus-like cytopathic agent isolated from swine farms with a history of recurrent abortion episodes was investigated. Evidence supporting the cytopathic agent as a mycoplasma-like organism was obtained but unlike M. hyopneumoniae, the organism was not propagated in Friis medium. Nucleotide sequence of 16S rRNA obtained from the cytopathic agent suggested that the newly isolated cytopathogenic swine mycoplasma was a variant form of M. hyorhinis. Striking homology between a portion of the 23S rRNA gene of M. hyorhinis and 5' UTR of human PTI-1 implicated that M. hyorhinis might potentially be related to the evolution of human PTI-1 (Shin JH, Joo HS, Lee WH, Seok HB, Calsamig M, Pijoan C, Molitor TW.Identification and characterization of cytopathogenic Mycoplasma hyorhinis from swine farms with a history of abortions. J Vet Med Sci. 2003 Apr;65(4):501-9.)

The variability of strain-specific surface lipoproteins and their potential role in shielding the wall-less mycoplasma surface from host Abs capable of binding vital (and as-yet-unidentified) surface antigens of this organism has been extensively studied (Citti C, Kim MF, Wise KS. Elongated versions of Vlp surface lipoproteins protect Mycoplasma hyorhinis escape variants from growth-inhibiting host antibodies.Infect Immun. 1997 May;65(5):1773-85). Three genes, vlpA, vlpB, and vlpC, have been previously identified in clonal isolates of M. hyorhinis SK76. Each is linked to a characteristic promoter region containing a homopolymeric tract of adenine residues [poly(A) tract], subject to hypermutation, that transcriptionally controls phase variation of vlp genes and leads to combinatorial surface mosaics of distinct Vlp products. These findings demonstrate a vastly expanded potential for structural diversity and combinatorial display of surface mosaics on this organism and suggest that modulation of the vlp repertoire, possibly in conjunction with mobile elements, may determine the capacity for surface variation in natural populations and laboratory strains of this mycoplasma species. (Citti,C., Watson-McKown,R., Droesse,M., Wise,K.S. J. Bacteriol. 182 (5), 1356-1363 (3 2000))

Why is it important to research community?

The broad objective of this work is increased understanding of mycoplasmal host-range and pathogenic determinants through comparison of conserved and variable features of mycoplasmal genomes. Mycoplasmas are important pathogens with usually strict natural host tropism and poorly-understood virulence mechanisms. Diverse mycoplasmas are known from all vertebrates except amphibians, but their epidemiology is dominated by mycoplasmoses of humans and the domesticated animals that humans use. However, mycoplasmas from wildlife are not simply curiosities: interactions with non-human, undomesticated animals must have been of central significance in shaping the evolution of mycoplasmoses of all animals and humans. Mycoplasma hyorhinis constitutes an example of a possible emerging human pathogen - host interaction in an understudied ecological and evolutionary niche. The etiology, pathology, diagnosis, treatment, and epidemiology of infectious diseases are also issues of broad significance to captive husbandry and conservation of many species of wildlife.

Furthermore, mycoplasmas (including M. hyorhinis) are being increasingly investigated as human pathogens with links to the onset of cancer. In a recent study, Fifty of 90 cases (56%) of gastric carcinoma were positive for mycoplasma hyorhinis. In other gastric diseases, the mycoplasma infection ratio was 28% (18/49) in chronic superficial gastritis, 30% (14/46) in gastric ulcer and 37% (18/49) in intestinal metaplasia. In colon carcinoma, the mycoplasma infection ratio was 55.1% (32/58),but it was 20.9% (10/49)in adenomarous polyp (chi(2)=13.46, P < 0.005). Gastric and colon cancers with high differentiation had a higher mycoplasma infection ratio than those with low differentiation (P < 0.05). Mycoplasma infection in esophageal cancer, lung cancer, breast cancer and glioma was 50.9% (27/53), 52.6% (31/59), 39.7% (25/63) and 41% (38/91), respectively. Overall, there was high correlation between mycoplasma infection and different cancers, which suggests the possibility of an association between the two. The mechanism involved in oncogenesis by mycoplasma remains unknown.(Huang S, Li JY, Wu J, Meng L, Shou CC.Mycoplasma infections and different human carcinomas. World J Gastroenterol. 2001 Apr;7(2):266-9.)

Available genone information about this organism?

The mollicutes include the smallest free-living cells and have the smallest genomes among eubacteria. Degenerative evolution from Gram-positive ancestors conserved a high percentage of the genes essential for life, making mycoplasmas ideal candidates for whole-genome sequence determination and gene identification. Complete nucleotide sequences of genomes of 9 mollicute species have been published within the last few years and entire sequences of several others are nearing completion. Analyses of the genomes of mollicutes are widely expected to contribute to better understanding of disease pathophysiology and targets for therapeutic intervention, identification of host-specific genes, and factors influencing genome plasticity and evolution.

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Sequencing Strategies

This is the place to give a brief summary of the sequencing strategies used in this project. Topics need to discuss include, but not limited, to the following

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Annotation Strategies

Contigs were analyzed by FGENESB. Each predicted ORF was BLAST searched against NCBI NR database.

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Personnel

Participants are listed in alphabetical order.

Students

Kogenta Nakamura, Postdoctoral Fellow
Department of Surgery
University of Florida

 		Faculties & Staffs

Steve Goodison, Associate Professor
Department of Surgery
University of Florida

Charels J Rosser, Assistant Professor
Department of Surgery
University of Florida

Virginia Urquidi, Associate Professor
Department of Surgery
University of Florida

William G. Farmerie, Assistant Scientist
Interdisciplinary Center for Biotechnology Research (ICBR)
University of Florida

Li Liu, Bioinformatics Specialist
Interdisciplinary Center for Biotechnology Research (ICBR)
University of Florida

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