Galleria mellonella is an effective model to study Actinobacillus pleuropneumoniae infection

Abstract

Actinobacillus pleuropneumoniae is responsible for swine pleuropneumonia, a respiratory disease that causes significant global economic loss. Its virulence depends on many factors, such as capsular polysaccharides, RTX toxins and iron-acquisition systems. Analysis of virulence may require easy-to-use models that approximate mammalian infection and avoid ethical issues. Here, we investigate the potential use of the wax moth Galleria mellonella as an informative model for A. pleuropneumoniae infection. Genotypically distinct A. pleuropneumoniae clinical isolates were able to kill larvae at 37 6C but had different LD 50 values, ranging from 10 4 to 10 7 c.f.u. per larva.The most virulent isolate (1022) was able to persist and replicate within the insect, while the least virulent (780) was rapidly cleared. We observed a decrease in haemocyte concentration, aggregation and DNA damage post-infection with isolate 1022. Melanization points around bacterial cells were observed in the fat body and pericardial tissues of infected G. mellonella, indicating vigorous cell and humoral immune responses close to the larval dorsal vessel. As found in pigs, an A. pleuropneumoniae hfq mutant was significantly attenuated for infection in the G. mellonella model. Additionally, the model could be used to assess the effectiveness of several antimicrobial agents against A. pleuropneumoniae in vivo. G. mellonella is a suitable inexpensive alternative infection model that can be used to study the virulence of A. pleuropneumoniae, as well as assess the effectiveness of antimicrobial agents against this pathogen.

A computational strategy for the search of regulatory small RNAs in Actinobacillus pleuropneumoniae

“…Although the relevance of sRNAs in A. pleuropneumoniae pathogenesis is suggested by previous work with mutants for the sRNA molecular chaperone Hfq (Subashchandrabose et al 2013;Pereira et al 2015b), little information exists on abundance and possible roles.…”

“…We envisage that the Arccs discovered in our study are negative regulators, although further experiments, e.g., comparative RNA-seq Most sRNAs have as targets mRNAs directly implicated in either virulence or stress resistance. Although this was partially expected given the aforementioned phenotypes of reduced biofilm-forming capacity, sensitivity to oxidative stress (Subashchandrabose et al 2013), and reduced virulence in an alternative infection model (Pereira et al 2015b) displayed by A. pleuropneumoniae mutants for the hfq gene, new candidates for virulence determinants were defined by the present regulatory network. Two categories of potential targets that are part of extremely important systems for the establishment of A. pleuropneumoniae as a pig pathogen, and thus strong mutant candidates for live attenuated vaccines, are the iron-acquisition systems and Apx toxins.…”

“…The pathogenesis of pleuropneumonia is complex and involves many virulence factors, of which the Apx toxins, of the RTX family, are believed to play a central role (Frey 2011). Recently, A. pleuropneumoniae hfq mutants were shown to be defective in biofilm formation, displayed enhanced sensitivity to oxidative stress (Subashchandrabose et al 2013), and were attenuated in an alternative infection model (Pereira et al 2015b). Hfq is an RNA-binding protein that facilitates the pairing of sRNAs with their target mRNAs and affects gene expression (Vogel and Luisi 2011).…”

Galleria mellonella as a model system to assess the efficacy of antimicrobial agents against Klebsiella pneumoniae infection

“…This could be due to variations in infection dynamics. 13 High-virulence strain (GN0576) is able to grow within the host, while low-virulence strain (GN0690) is not able to. We found that killing of G. mellonella larvae depended on the number of bacteria inoculated.…”

“…larvae over other invertebrate models is their ability to survive at 37 °C, the mammalian body temperature. 8,13 G. mellonella was used as a model system to study A. baumannii pathogenesis and therapeutics. 5 McLaughlin et al 14 quantified the clinical virulence of K. pneumoniae producing carbapenemase K. pneumoniae with a G. mellonella model.…”