Factors influencing the cell adhesion and invasion capacity of Mycoplasma gallisepticum

Abstract

BackgroundThe cell invasiveness of Mycoplasma gallisepticum, the causative agent of respiratory disease in chickens and infectious sinusitis in turkeys, may be a substantial factor in the well-known chronicity of these diseases and in the systemic spread of infection. To date, not much is known about the host factors and mechanisms involved in promotion or obstruction of M. gallisepticum adherence and/or cell invasion.In the current study, the influence of extracellular matrix (ECM) proteins such as fibronectin, collagen type IV and heparin, as well as plasminogen/plasmin, on the adhesion and cell invasion levels of M. gallisepticum to chicken erythrocytes and HeLa cells was investigated in vitro. Two strains, Rhigh and Rlow, which differ in their adhesion and invasion capacity, were analyzed by applying a modified gentamicin invasion assay. Binding of selected ECM molecules to M. gallisepticum was proven by Western blot analysis.ResultsCollagen type IV, fibronectin, and plasminogen exerted positive effects on adhesion and cell invasion of M. gallisepticum, with varying degrees, depending on the strain used. Especially strain Rhigh, with its highly reduced cell adhesion and invasion capabilities seemed to profit from the addition of plasminogen. Western and dot blot analyses showed that Rhigh as well as Rlow are able to adsorb horse fibronectin and plasminogen present in the growth medium. Depletion of HeLa cell membranes from cholesterol resulted in increased adhesion, but decreased cell invasion.ConclusionECM molecules seem to play a supportive role in the adhesion/cell invasion process of M. gallisepticum. Cholesterol depletion known to affect lipid rafts on the host cell surface had contrary effects on cell adherence and cell invasion of M. gallisepticum.

In vitro and in vivo cell invasion and systemic spreading of Mycoplasma agalactiae in the sheep infection model

“…The ability of M. agalactiae to invade mammalian cells was investigated by infecting three different mammalian cell lines with the pathogenic type strain PG2. Apart from HeLa, which is a standard epithelial cell line used in many mycoplasma invasion studies ( Andreev et al, 1995; Winner et al, 2000; Yavlovich et al, 2004; Marques et al, 2010; Fürnkranz et al, 2013; Hopfe et al, 2013 ), gentamicin invasion assays were also performed on cultured ruminant cells, namely BEND and BLF. PG2 cells were incubated with these mammalian cells at an MOI of 10–30 for 4, 8, 16 and 24 h before subjecting them to gentamicin treatment to kill extracellular bacteria and then directly plated onto SP4 agar to enumerate viable intracellular bacteria by cfu counts.…”

“…Mycoplasmas are generally considered extracellular pathogens although in the last decades there have been quite a few reports providing sufficient evidence for some of these species to be capable of invading eukaryotic host cells ( Fürnkranz et al, 2013 ). However, for M. agalactiae , which is well known for its chronic and persistent infections, cell invasion, and for that matter even a precise or direct account of its cytadherence capability, considering adherence to be a prerequisite for invasion, is yet to come.…”

“…It is thus clear that like many other bacterial pathogens, the division between intracellular and extracellular mycoplasmas is becoming increasingly blurred as more and more pathogens originally believed to be extracellular are now shown to have alternative intracellular lifestyles ( Bower et al, 2005; Fürnkranz et al, 2013; Lamberti et al, 2013 ). This alternative capacity of M. agalactiae , even if it is exhibited by a very small subpopulation of total infected cells, might provide the pathogen with a gross advantage at the population level to hide from antibiotics and host immune responses and to navigate through the host body to reestablish infection in new host niches, thus causing persistent infections that are difficult to eradicate.…”

Invasion and persistence of Mycoplasma bovis in embryonic calf turbinate cells

“…This hypothesis could explain the inconsistent blocking of entry with MDC and CPZ through the switching to another mechanism of M. bovis entry in PECT cells. MDC and CPZ are known to indirectly impact actin dynamics; MDC via inhibition of transglutaminases and CPZ through inhibition of phospholipase C [ 54 ]. These chemicals may also potentially interfere to a various extent with an alternative mechanism of cell entry requiring actin assembly and dynamics.…”

Multiple differences in pathogen-host cell interactions following a bacterial host shift

“…Given that we have no knowledge of the progenitor poultry strain at the origin of the house finch clade of M. gallisepticum, we cannot use R_low (or R_high) as a representative ancestral strain. Rather, R_low and R_high were chosen as references in our experiments because they are well characterised, and many of their virulence related attributes, representing those that we wished to investigate in the house finch strain, have been comprehensively studied 18,22,[34][35][36][37][38][39] . We used the HF_1994 strain to characterise the virulence phenotype at the point of outbreak because it represents the earliest strain collected following first observation of disease in the house finch, and because its genome has been sequenced (GenBank accession number CP003506) 31 .…”