RNA-seq analysis of LPS-induced immune priming in silkworms (Bombyx mori) and the role of cytochrome P450 detoxification system in the process.

While immune priming has been identified in many invertebrates, the intricate mechanisms that drive this process in insects continue to be a subject of mystery. In this study, we exposed silkworm larvae to varying doses of lipopolysaccharide (LPS) to induce immune priming and assessed their survival upon challenge with Bacillus thuringiensis (Bt). Transcriptome analysis was performed to identify differentially expressed genes (DEGs) associated with immune priming.

Transcriptome analysis reveals immune and metabolic regulation effects of polysaccharides on larvae.

polysaccharides (PS) have been used as Chinese traditional medicine with various pharmacological effects, including antiviral, anti-oxidative, and immunomodulatory activities. Herein silkworm was used as a model animal to evaluate the immunomodulatory effects of PS detecting the changes of innate immune parameters and explore the underlying molecular mechanism of the immunoregulatory effect of PS using Illumina HiSeq Xten platform. The results presented here demonstrated that a hemocoel injection of PS significantly enhanced the cellular immunity of silkworm, including hemocyte phagocytosis, microaggregation, and spreading ability.

Prior infection of Galleria mellonella with sublethal dose of Bt elicits immune priming responses but incurs metabolic changes.

Invertebrate immune priming has attracted wide attention of biologists in recent years because it challenges core notions about the disparate nature of acquired and innate immunity. However, the metabolic switch and energetic cost during eliciting immune priming are poorly investigated issues, which could widen and deepen our understanding of the physiological mechanism of immune priming. In this study, using sublethal dose of Bacillus thuringiensis (Bt) as an elicitor, we detected typical immune priming responses in Galleria mellonella.

RNA-seq profiles of putative genes involved in specific immune priming in Bombyx mori haemocytes.

Background: The immune system of many invertebrates, including insects, has been shown to comprise memory, or specific immune priming. However, knowledge of the molecular mechanisms especially the candidate immune-related genes mediated the specificity of the immune priming are still very scarce and fragmentary. We therefore used two closely related Gram-negative pathogenic bacteria (Photorhabdus luminescens TT01 and P.

Transcriptome analysis of differentially expressed genes involved in innate immunity following Bacillus thuringiensis challenge in Bombyx mori larvae.

In this study, we describe RNA-seq expression profiling of larval Bombyx mori response to hemocoel injection of Bacillus thuringiensis (Bt). Two transcriptomes were generated from the hemocytes of the PBS- and Bt-injected B. mori larvae.

Haemocoel injection of PirAB to Galleria mellonella larvae leads to disruption of the haemocyte immune functions.

The bacterium Photorhabdus luminescens produces a number of insecticidal proteins to kill its larval prey. In this study, we cloned the gene coding for a binary toxin PirAB and purified the recombinant protein using affinity chromatography combined with desalination technology. Furthermore, the cytotoxicity of the recombinant protein against the haemocytes of Galleria mellonella larvae was investigated.

Ultrastructural and functional characterization of circulating hemocytes from Galleria mellonella larva: Cell types and their role in the innate immunity.

Galleria mellonella larvae have been widely used as a model to study the virulence of various human pathogens. Hemocytes play important roles in the innate immune response of G. mellonella.

Galleria mellonella larvae are capable of sensing the extent of priming agent and mounting proportionatal cellular and humoral immune responses.

Larvae of Galleria mellonella are useful models for studying the innate immunity of invertebrates or for evaluating the virulence of microbial pathogens. In this work, we demonstrated that prior exposure of G. mellonella larvae to high doses (1×10(4), 1×10(5) or 1×10(6) cells/larva) of heat-killed Photorhabdus luminescens TT01 increases the resistance of larvae to a lethal dose (50 cells/larva) of viable P.

Eicosanoids mediate Galleria mellonella immune response to hemocoel injection of entomopathogenic nematode cuticles.

Entomopathogenic nematodes are symbiotically associated with bacteria and widely used in biological control of insect pests. The interference of symbiotic bacteria with insect host immune responses is fairly well documented. However, knowledge of mechanisms regulating parasite–host interactions still remains fragmentary.

No evidence for priming response in Galleria mellonella larvae exposed to toxin protein PirA2B2 from Photorhabdus luminescens TT01: An association with the inhibition of the host cellular immunity.

There is accumulating evidence that many invertebrates including insects can acquire enhanced immune protection against subsequently pathogens infection through immune priming. However, whether the toxin protein from pathogenic bacteria can induce such priming response remains unclear. Here we cloned, expressed and purified the toxin Photorhabdus insect-related proteins A2B2 (PirA2B2) from Photorhabdus luminescens TT01.

The specificity of immune priming in silkworm, Bombyx mori, is mediated by the phagocytic ability of granular cells.

In the past decade, the phenomenon of immune priming was documented in many invertebrates in a large number of studies; however, in most of these studies, behavioral evidence was used to identify the immune priming. The underlying mechanism and the degree of specificity of the priming response remain unclear. We studied the mechanism of immune priming in the larvae of the silkworm, Bombyx mori, and analyzed the specificity of the priming response using two closely related Gram-negative pathogenic bacteria (Photorhabdus luminescens TT01 and P.

The lipopolysaccharide (LPS) of Photorhabdus luminescens TT01 can elicit dose- and time-dependent immune priming in Galleria mellonella larvae.

In this work, we primed Galleria mellonella larvae by haemocoel injection of lipopolysaccharide (LPS) extracted from Photorhabdus luminescens TT01 to determine whether bacterial LPS can induce enhanced immune protection (recently called immune priming). We also analyzed the relationship between changes in the levels of innate immune elements and the degree of enhanced immune protection in the larvae at designated time points after priming. The larvae that received experimental doses (20.

Effects of dietary heavy metals on the immune and antioxidant systems of Galleria mellonella larvae.

In this work, we analyzed the effects of chromium (Cr) and lead (Pb) on immune and antioxidant systems of Galleria mellonella. In particular, after exposure to diets containing environmentally relevant concentrations (5, 50 and 100 μg/g) of Cr or Pb for 7 d, alterations in innate immune parameters and the activity of endogenous enzymes were measured in larvae. The results showed that 1) compared with the control, the lowest doses (5 μg/g) of Cr and Pb significantly increased the levels of innate immune parameters (total hemocyte count, THC; phagocytic activity; extent of encapsulation) of the larvae and hemolymph immune enzyme activities (acid phosphatase, ACP; alkaline phosphatase, AKP; phenoloxidase, PO), whereas the highest doses (100 μg/g) of Cr and Pb inhibited them; 2) the activity of antioxidant enzymes (superoxide dismutase, SOD; peroxidase, POD; catalase, CAT) showed significant increases with increasing concentrations of dietary Cr and Pb, and were significantly higher than those of the control; and 3) feeding the larvae with experimental concentrations of either Cr or Pb resulted similar patterns of changes of all the parameters examined.