Prior infection of Manduca sexta with non-pathogenic Escherichia coli elicits immunity to pathogenic Photorhabdus luminescens: Roles of immune-related proteins shown by RNA interference

Eleftherianos, Ioannis; Marokházi, Judit; Millichap, Peter J.; Hodgkinson, Alan; Sriboonlert, Ajaraporn; ffrench-Constant, Richard H.; Reynolds, Stuart E.

doi:10.1016/j.ibmb.2006.04.001

Cited by 108 publications

(81 citation statements)

References 27 publications

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“…In several cases, constitutive expression of the Imd pathway of AMP genes results in host protection 49,50,80,81 , which reveals the importance of the race between the establishment of resistant bacterial populations and the activation of the immune response. Furthermore, it demonstrates that the host immune response can be effective against invaders.…”

Section: Discussionmentioning

confidence: 99%

Bacterial strategies to overcome insect defences

2008

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| Recent genetic and molecular analyses have revealed how several strategies enable bacteria to persist and overcome insect immune defences. Genetic and genomic tools that can be used with Drosophila melanogaster have enabled the characterization of the pathways that are used by insects to detect bacterial invaders and combat infection. Conservation of bacterial virulence factors and insect immune repertoires indicates that there are common strategies of host invasion and pathogen eradication. Long-term interactions of bacteria with insects might ensure efficient dissemination of pathogens to other hosts, including humans. R E V I E W S302 | APRIL 2008 | voLUME 6 www.nature.com/reviews/micro

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Section: Discussionmentioning

confidence: 99%

Bacterial strategies to overcome insect defences

2008

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“…Hemocytes (30 mg) and fat body (100 mg) were homogenised in 1 ml of TRI reagent (Sigma, Gillingham, UK). RNA was then isolated as described (Eleftherianos et al, 2006a;Eleftherianos et al, 2006b). All RNA samples were treated with RNase-free DNaseI (Invitrogen, Paisley, UK) (1 U μl -1 ), and lack of DNA contamination was confirmed in every case by performing PCR without the reverse transcriptase (RT) step.…”

Section: Rna Extraction Rt-pcr and Cdna Cloningmentioning

confidence: 99%

“…All RNA samples were treated with RNase-free DNaseI (Invitrogen, Paisley, UK) (1 U μl -1 ), and lack of DNA contamination was confirmed in every case by performing PCR without the reverse transcriptase (RT) step. Single-step reverse transcription (RT)-PCR and cDNA cloning of proPSP were as previously described (Eleftherianos et al, 2006a;Eleftherianos et al, 2006b). Primers were designed from the sequence of the M. sexta proPSP cDNA (GenBank accession no.…”

Section: Rna Extraction Rt-pcr and Cdna Cloningmentioning

confidence: 99%

Plasmatocyte-spreading peptide (PSP) plays a central role in insect cellular immune defenses against bacterial infection

Eleftherianos

Yadi

et al. 2009

Journal of Experimental Biology

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SUMMARYInsect hemocytes (blood cells) are a central part of the insect's cellular response to bacterial pathogens, and these specialist cells can both recognize and engulf bacteria. During this process, hemocytes undergo poorly characterized changes in adhesiveness. Previously, a peptide termed plasmatocyte-spreading peptide (PSP), which induces the adhesion and spreading of plasmatocytes on foreign surfaces, has been identified in lepidopteran insects. Here, we investigate the function of this peptide in the moth Manduca sexta using RNA interference (RNAi) to prevent expression of the precursor protein proPSP. We show that infection with the insect-specific bacterial pathogen Photorhabdus luminescens and non-pathogenic Escherichia coli induces proPSP mRNA transcription in the insect fat body but not in hemocytes; subsequently, proPSP protein can be detected in cell-free hemolymph. We used RNAi to silence this upregulation of proPSP and found that the knock-down insects succumbed faster to infection with P. luminescens, but not E. coli. RNAi-treated insects infected with E. coli showed a reduction in the number of circulating hemocytes and higher bacterial growth in hemolymph as well as a reduction in overall cellular immune function compared with infected controls. Interestingly, RNAi-mediated depletion of proPSP adversely affected the formation of melanotic nodules but had no additional effect on other cellular responses when insects were infected with P. luminescens, indicating that this pathogen employs mechanisms that suppress key cellular immune functions in M. sexta. Our results provide evidence for the central role of PSP in M. sexta cellular defenses against bacterial infections. Supplementary material available online at

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“…Injection of hemolin dsRNA left the insect more susceptible to P. luminescens infection than insects that had not experienced prior infection with E. coli [66]. Table 1.…”

Section: ) Hemolinmentioning

confidence: 99%