Membrane vesicles released byAvibacterium paragallinarumcontain putative virulence factors

Abstract

Avibacterium paragallinarum, the causative agent of infectious coryza, releases extracellular membrane vesicles (MVs), containing immunogenic proteins, proteases, putative RTX proteins, haemagglutinin, and nucleic acids, into the medium. MVs ranging 50-300 nm in diameter were observed by electron microscopy. They contained immunogenic proteins in the range of 20-160 kDa, detected using vaccinated or experimentally infected chicken sera raised against Av. paragallinarum, but not in pooled sera from specific pathogen-free chickens. Proteolytic activity was not detected in MVs through zymograms; however, immune recognition of high molecular mass bands was observed by Western blotting using an antiprotease serum against Actinobacillus pleuropneumoniae serotype 1 purified protease, suggesting its presence. MVs agglutinated glutaraldehyde-fixed chicken red blood cells indicating the presence of haemagglutinating antigens. Nucleic acids were also detected inside MVs. Avibacterium paragallinarum releases MVs containing putative virulence factors, which could be important in the pathogenesis of infectious coryza.

Component Identification and Functional Analysis of Outer Membrane Vesicles Released by Avibacterium paragallinarum

“…An earlier study on the OMVs of A. paragallinarum reported the presence of putative repeats-in-toxin (RTX) proteins (Ramon Rocha et al, 2006). The putative toxins were detected by immunoblotting (Ramon Rocha et al, 2006), which may explain why our study, based on direct SDS-PAGE examination and mass spectrometry, failed to detect similar proteins.…”

“…An earlier study on the OMVs of A. paragallinarum reported the presence of putative repeats-in-toxin (RTX) proteins (Ramon Rocha et al, 2006). The putative toxins were detected by immunoblotting (Ramon Rocha et al, 2006), which may explain why our study, based on direct SDS-PAGE examination and mass spectrometry, failed to detect similar proteins. In another difference, we failed to detect HA activity in our OMV preparation, an activity that was detected by Ramon Rocha et al (2006) who detected this activity on a concentrated OMV preparation.…”

“…The release of outer membrane vesicles (OMVs) by Gram-negative bacteria has been observed and extensively studied over the past decades ( Jan, 2017 ), including Haemophilus influenzae ( Deich and Hoyer, 1982; Roier et al, 2016 ) and A. paragallinarum ( Ramon Rocha et al, 2006 ) in the family Pasteurellaceae . OMVs are ubiquitously produced both in vitro and in vivo during an infection ( Roier et al, 2016 ) and play a crucial role in host-microbe interactions ( Turnbull et al, 2016 ).…”

Bacterial determinants of importance in the virulence of Gallibacterium anatis in poultry

“…OMVs have also been shown to act as transportation vehicles for the delivery of lipids, membrane proteins, insoluble compounds or compounds that are easily degraded, including toxins and DNA. The transport of proteases and hemolysins by OMVs has been shown for Actinobacillus pleuropneumoniae and Avibacterium paragallinarum [ 73 , 74 ]. However, vesicles from G. anatis do not seem to be involved in either hemolysis or proteolysis (unpublished data).…”

Outer membrane vesicles of Pasteurella multocida contain virulence factors

“…Membranes were blocked with skim milk for 1 h at room temperature, incubated with either rabbit hyperimmune serum against an Actinobacillus pleuropneumoniae-purified protease (Negrete-Abascal et al 1998) or a pool of serum samples from chickens infected with Pm. Membranes were processed as described previously by Ram on Rocha et al (2006).…”