Immunomodulation by Mycoplasmas: Artifacts, Facts and Active Molecules

Mühlradt, Peter F.

doi:10.1007/0-306-47606-1_20

Cited by 13 publications

(11 citation statements)

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“…One hallmark of these diseases is disease chronicity (47,54), but equally important is the ability to alter or circumvent the immune response and potentiate disease due to other pathogens (5,37,54). Mycoplasma hyopneumoniae is the causative agent of porcine enzootic pneumonia, a mild, chronic pneumonia of swine commonly complicated by opportunistic infections with other bacteria (46).…”

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The Genome Sequence ofMycoplasma hyopneumoniaeStrain 232, the Agent of Swine Mycoplasmosis

et al. 2004

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confidence: 99%

The Genome Sequence ofMycoplasma hyopneumoniaeStrain 232, the Agent of Swine Mycoplasmosis

et al. 2004

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“…These include depletion of essential nutrients, promotion of chromosome aberrations and malignant transformation, immunomodulation and alteration in virus replication (McGarrity et al, 1992;Lo, 2002;Mühlradt, 2002).…”

Section: Damage To the Hostmentioning

confidence: 98%

Poultry mycoplasmas: sophisticated pathogens in simple guise

Bradbury¹

2005

British Poultry Science

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Mycoplasmas are a genus within the class Mollicutes (trivial name mollicutes), which are the smallest known prokaryotes capable of self-replication. They have a very small genome, and have evolved to this 'minimalist' status by losing non-essential genes, including those involved in cell wall synthesis. The mollicutes exploit their limited genetic material to the maximum and many are successful pathogens in man, animals, birds and plants. Most of those of veterinary importance are in the genus Mycoplasma and include 4 poultry pathogens of economic importance: Mycoplasma gallisepticum, Mycoplasma synoviae, Mycoplasma meleagridis and Mycoplasma iowae. The pathogenetic mechanisms of mycoplasmas are not fully understood, but they are successful pathogens because they can enter the host and multiply, evade the defence mechanisms, cause damage and escape to infect new hosts. M. gallisepticum is one of several motile species and possesses a terminal tip structure that mediates adherence to its target tissues. For some species, including M. gallisepticum, some of the organisms may become intracellular. Some Mycoplasma species, including the pathogenic poultry species, have a remarkable ability to vary their major surface antigens, a mechanism that is thought to help them to persist in their host by evading the immune response. The molecular and cellular events that lead to the development of lesions and clinical disease are still obscure. Some lesions appear to be the result of indirect damage from the host's inflammatory and cellular responses. Despite short survival times in the environment, mycoplasmas are able to transmit successfully to new hosts. In poultry flocks there is both horizontal and vertical transmission, the former being encouraged by intensive husbandry and stress factors. Establishing the pathways of transmission and the possible role of other birds, such as game and wild birds, as intermediate vectors between poultry flocks is now greatly aided by the availability of modern molecular methods for strain typing.

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“…M. fermentans has received attention both for its potential roles as a primary or contributing pathogen in human disease (18,25) and due to the recent discovery of potent macrophage-modulating activity associated with distinctively modified surface lipoproteins (7,(30)(31)(32)(33)41). M. fermentans displays several variable surface proteins, some lacking orthologous counterparts in other organisms and others with assignable specific functions (6,10,11,45,46,49 In previous studies (44), P29 was shown to be an abundant surface lipoprotein of 29 kDa.…”

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Identification and Functional Mapping of theMycoplasma fermentansP29 Adhesin

Leigh

Wise

2002

Infect Immun

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Initial adherence interactions between mycoplasmas and mammalian cells are important for host colonization and may contribute to subsequent pathogenic processes. Despite significant progress toward understanding the role of specialized, complex tip structures in the adherence of some mycoplasmas, particularly those that infect humans, less is known about adhesins through which other mycoplasmas of this host bind to diverse cell types, even though simpler surface components are likely to be involved. We show by flow cytometric analysis that a soluble recombinant fusion protein (FP29), representing the abundant P29 surface lipoprotein of Mycoplasma fermentans, binds human HeLa cells and inhibits M. fermentans binding to these cells, in both a quantitative and a saturable manner, whereas analogous fusion proteins representing other mycoplasma surface proteins did not. Constructs representing nested N-or C-terminal truncations of FP29 allowed initial mapping of this specific adherence function to a central region of the P29 sequence containing a 36-amino-acid disulfide loop. A derivative of FP29 containing a mutation converting one participating Cys to Ser, precluding intrachain disulfide bond formation, retained full activity. Together these results suggest that the direct interaction of M. fermentans with a ligand on the HeLa cell surface involves a limited segment of the P29 surface lipoprotein and requires neither the disulfide bond nor the contribution of adjacent portions of the protein.Earlier results indicating phase-variable display of monoclonal antibody surface epitopes on P29, now recognized to be outside this ligand binding region, raise the possibility that variation of mycoplasma surface architecture might alter the presentation of the binding region and the adherence phenotype. Preliminary results further indicated that FP29 could inhibit binding to HeLa cells by Mycoplasma hominis, a distinct human mycoplasma species displaying the phase-variable adhesin Vaa, but not that by Mycoplasma capricolum, an organism infecting caprine species. This result raises the additional, testable possibility that a common host cell ligand for two human mycoplasma species may be recognized through structurally dissimilar adhesins that undergo phase variation by two distinct mechanisms, governing protein expression (Vaa) or surface masking (P29).Mycoplasmal adherence to host cells is critical for colonization and maintenance of infection (34,35). As a manifestation of the widely observed phenomenon of adaptive surface diversification (34, 51), some mycoplasmas display spontaneous loss and reacquisition of specific adhesins and corresponding adherence phenotypes (4,21,34). Identification and characterization of mycoplasma adhesins (19) and their role in virulence continue to be studied, including those of human mycoplasmal species. Perhaps most thoroughly examined are mycoplasma adhesins associated with the terminal tip organelle of some species, composed of multiple interacting proteins (4,21,23,34,37). The ligand bind...

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Immunomodulation by Mycoplasmas: Artifacts, Facts and Active Molecules

Cited by 13 publications

References 113 publications

The Genome Sequence ofMycoplasma hyopneumoniaeStrain 232, the Agent of Swine Mycoplasmosis

The Genome Sequence ofMycoplasma hyopneumoniaeStrain 232, the Agent of Swine Mycoplasmosis

Poultry mycoplasmas: sophisticated pathogens in simple guise

Identification and Functional Mapping of theMycoplasma fermentansP29 Adhesin

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