Mycoplasma Adherence

Razin, Shmuel

doi:10.1016/b978-0-12-078404-2.50012-9

Cited by 43 publications

(31 citation statements)

References 116 publications

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“…A flask-or club-like cell shape with a protruding tip or bleb structure has been observed in pathogenic mycoplasmas (12,19), and there is evidence for the presence of cytoskeletal elements in M. pneumoniae (9). While the tip-like structures of Mycoplasma penetrans and Mycoplasma genitalium are involved in the invasion of host cells (11,16), the morphologically different stalks of the Mycoplasma-like symbionts of P. scaber appear to serve merely in adhesion to the host endothelium.…”

Section: Discussionmentioning

confidence: 99%

“CandidatusHepatoplasma crinochetorum,” a New, Stalk-Forming Lineage ofMollicutesColonizing the Midgut Glands of a Terrestrial Isopod

Wang

Stingl

Anton-Erxleben

et al. 2004

Appl Environ Microbiol

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Uncultivated bacteria that densely colonize the midgut glands (hepatopancreas) of the terrestrial isopodPorcellio scaber (Crustacea: Isopoda) were identified by cloning and sequencing of their 16S rRNA genes. Phylogenetic analysis revealed that these symbionts represent a novel lineage of the Mollicutes and are only distantly related (<82% sequence identity) to members of the Mycoplasmatales and Entomoplasmatales. Fluorescence in situ hybridization with a specific oligonucleotide probe confirmed that the amplified 16S rRNA gene sequences indeed originated from a homogeneous population of symbionts intimately associated with the epithelial surface of the hepatopancreas. The same probe also detected morphotypically identical symbionts in other crinochete isopods. Scanning and transmission electron microscopy revealed uniform spherical bacterial cells without a cell wall, sometimes interacting with the microvilli of the brush border by means of stalk-like cytoplasmic appendages, which also appeared to be involved in cell division through budding. Based on the isolated phylogenetic position and unique cytological properties, the provisional name "Candidatus Hepatoplasma crinochetorum" is proposed for this new taxon of Mollicutes colonizing the hepatopancreas of P. scaber.The common woodlouse, Porcellio scaber (Crustacea: Isopoda), is a cosmopolitan species that feeds mainly on decaying plant material, such as leaf litter, wood, and grass (29), which are rich in recalcitrant structural polymers, such as cellulose, hemicelluloses, and lignins (3). Together with other terrestrial isopods (Oniscidea), P. scaber is thought to play an important role in decomposition processes and nutrient recycling (29).The hepatopancreas (digestive glands) of P. scaber, which consists of two pairs of tubular midgut ceca, functions in the secretion of digestive enzymes and the absorption of nutrients. The midgut ceca are densely colonized by microorganisms (8,25,27,28,31). It has been speculated that hepatopancreatic bacteria, like the gut symbionts of termites and other soil arthropods that feed on fiber-rich diets (3, 4), might be involved in the digestion of leaf litter, e.g., by producing cellulases or phenol oxidases (28,(30)(31)(32).Like many previous attempts to isolate bacteria associated with invertebrates, all efforts to culture the symbionts in vitro have failed. This has so far prevented both identification of the symbionts and analysis of the nature of the symbiotic association. In a previous report, it was shown that the hepatopancreas of P. scaber is colonized by a novel lineage of rod-shaped, stalk-forming symbionts that fall into the alpha subclass of the Proteobacteria but are only distantly related to the Rickettsiales (Ͻ81% sequence similarity) (25). In the course of a broader survey of the distribution of such Rickettsia-like symbionts among different populations of P. scaber, we observed that in many specimens the hepatopancreas contained spherical symbiotic bacteria instead of the rod-shaped forms.In the present stu...

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Section: Discussionmentioning

confidence: 99%

“CandidatusHepatoplasma crinochetorum,” a New, Stalk-Forming Lineage ofMollicutesColonizing the Midgut Glands of a Terrestrial Isopod

Wang

Stingl

Anton-Erxleben

et al. 2004

Appl Environ Microbiol

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“…Mycoplasma cytadhesins have been shown to bind to sialoand asialo-glucoconjugates as well as sulfated glycolipids (19,60,63). The present belief is that ADP1 molecules are primarily responsible for mycoplasma cytadherence and that MGPC gene product(s) play an accessory role in this process.…”

Section: Discussionmentioning

confidence: 99%

GapA and CrmA Coexpression Is Essential for Mycoplasma gallisepticum Cytadherence and Virulence

et al. 2002

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It was previously demonstrated that avirulent Mycoplasma gallisepticum strain R high (passage 164) is lacking three proteins that are expressed in its virulent progenitor, strain R low (passage 15). These proteins were identified as the cytadhesin molecule GapA, the putative cytadhesin-related molecule CrmA, and a component of a high-affinity transporter system, HatA. Complementation of R high with wild-type gapA restored expression in the transformant (GT5) but did not restore the cytadherence phenotype and maintained avirulence in chickens. These results suggested that CrmA might play an essential role in the M. gallisepticum cytadherence process. CrmA is encoded by the second gene in the gapA operon and shares significant sequence homology to the ORF6 gene of Mycoplasma pneumoniae, which has been shown to play an accessory role in the cytadherence process. Complementation of R high with wild-type crmA resulted in the transformant (SDCA) that lacked the cytadherence and virulence phenotype comparable to that found in R high and GT5. In contrast, complementation of R high with the entire wild-type gapA operon resulted in the transformant (GCA1) that restored cytadherence to the level found in wild-type R low . In vivo pathogenesis trials revealed that GCA1 had regained virulence, causing airsacculitis in chickens. These results demonstrate that both GapA and CrmA are required for M. gallisepticum cytadherence and pathogenesis.Mycoplasma gallisepticum is one infectious agent initiating the chronic respiratory disease complex in chickens and is the primary agent of infectious sinusitis in turkeys (74). This bacterium has developed a wide array of surface molecules that are involved in cytadherence to host cells (9,17,22,51). GapA is considered the primary cytadhesin. Goh et al. (21) identified its gene in M. gallisepticum based on its nucleotide sequence homology to the Mycoplasma pneumoniae cytadhesin ADP1 gene. Subsequent studies showed that anti-GapA Fab fragments were able to significantly inhibit M. gallisepticum cytadherence (22). Troy (69) reported that GapA was absent in avirulent M. gallisepticum. These data led us to hypothesize that complementation of GapA expression in strain R high via Tn4001 might restore cytadherence and perhaps virulence. Neither cytadherence nor virulence was restored upon the gapA-complemented strain R high , transformant GT5 (56, 57). This indicated that other factors might play an important role in M. gallisepticum cytadherence. Protein profile comparison between virulent and avirulent strains showed that, in addition to GapA, two other proteins are absent in R high (69). One of these proteins was found to be encoded by the second gene of the gapA operon. Its gene product shows significant sequence homology with the precursor of M. pneumoniae ORF6 gene products, which are known to play accessory roles in P1 (ADP1)-mediated cytadherence (35,36,40,66 The aim of this study was to evaluate the role of CrmA in M. gallisepticum cytadherence and virulence. We demonstrate that coexpr...

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“…Adherence of certain mycoplasmas to living cells and to inert surfaces is well documented (Razin, 1985;Balish and Krause, 2002) and the phenomenon of haemadsorption has provided an in vitro model for studying adherence to cells. Adhesion of mycoplasmas to epithelial cells is considered to be the first step in pathogenesis and has been studied mainly in relation to respiratory tract epithelium.…”

Section: Adherence To Host Tissuesmentioning

confidence: 99%

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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Mycoplasma Adherence

Cited by 43 publications

References 116 publications

“CandidatusHepatoplasma crinochetorum,” a New, Stalk-Forming Lineage ofMollicutesColonizing the Midgut Glands of a Terrestrial Isopod

“CandidatusHepatoplasma crinochetorum,” a New, Stalk-Forming Lineage ofMollicutesColonizing the Midgut Glands of a Terrestrial Isopod

GapA and CrmA Coexpression Is Essential for Mycoplasma gallisepticum Cytadherence and Virulence

Poultry mycoplasmas: sophisticated pathogens in simple guise

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