Mechanism of <i>Metarhizium rileyi</i> evading cellular immune responses in <i>Helicoverpa armigera</i>

Li, Li; Zhong, Ke; Wang, Jialin; Liu, Xusheng

doi:10.1002/arch.21769

Cited by 5 publications

(4 citation statements)

References 46 publications

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“…Therefore, we conclude that other PRRs, such as CTL3 identified here, may also contribute to the induction of AMPs. However, our previous study showed a lower affinity of βGRPs or CTL3 to M. rileyi hyphal bodies [ 27 ]. Given that ecdysone triggers the expression of many immune-related genes, such as PRRs and AMPs [ 42 , 63 ], an increased 20E titer upon M. rileyi infection may contribute to the upregulation of AMPs, either directly or indirectly.…”

Section: Discussionmentioning

confidence: 99%

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An entomopathogenic fungus exploits its host humoral antibacterial immunity to minimize bacterial competition in the hemolymph

et al. 2023

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Background The insect hemolymph (blood-equivalent fluid), composed of a large number of hemocytes (blood cells) and a variety of soluble immune effectors, is hostile for pathogens including fungi. In order to survive in the insect hemocoel (body cavity), the entomopathogenic fungus (EPF) has evolved two classical coping strategies, namely evasion and suppression of the host immune reactions. However, it remains unclear whether EPF has other ways of coping with host immunity. Results In this study, we demonstrated that Metarhizium rileyi (an EPF) infection by injection of blastospores into the hemocoel enhanced the plasma antibacterial activity of cotton bollworm (Helicoverpa armigera), which was partially due to the enhanced expression of antimicrobial peptides (AMPs). The early stage of M. rileyi infection induced the translocation of gut bacteria into the hemocoel, where they were subsequently cleared due to the enhanced plasma antibacterial activity. Further, we showed that the enhanced plasma antibacterial activity and AMP expression were attributable to M. rileyi but not the invasive gut bacteria (opportunistic bacteria). Elevated ecdysone (major steroid hormone in insects) levels in the hemolymph at 48 h post-M. rileyi infection might contribute to the enhanced expression of AMPs. The fungus-elicited AMPs, such as cecropin 3 or lebocin, exhibited potent inhibitory activity against the opportunistic bacteria but not against hyphal bodies. In addition, the opportunistic bacteria competed with hyphal bodies for amino acid nutrients. Conclusions M. rileyi infection induced the translocation of gut bacteria, and then the fungi activated and exploited its host humoral antibacterial immunity to eliminate opportunistic bacteria, preventing them from competing for nutrients in the hemolymph. Unlike the classical strategies, EPF utilizes to evade or suppress host immunity, our findings reveal a novel strategy of interaction between EPF and host immunity.

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Section: Discussionmentioning

confidence: 99%

“…We have previously demonstrated that the infection of Metarhizium rileyi (also known as Nomuraea rileyi ) impairs and evades cellular immunity in the lepidopteran insect Helicoverpa armigera [ 26 , 27 ]. In the current study, we found that M. rileyi infection stimulated plasma antibacterial activity and enhanced the AMP expression.…”

Section: Introductionmentioning

confidence: 99%

An entomopathogenic fungus exploits its host humoral antibacterial immunity to minimize bacterial competition in the hemolymph

et al. 2023

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“…lower glucan contents compared to other propagules like submerged conidia and hyphae, which may contribute to their ability to evade host immune responses ( 31 , 50 , 120 , 121 ). For example, hyphal bodies of M. rileyi induce weaker cellular immune responses in the body cavity of Helicoverpa armigera caterpillars compared to M. rileyi conidia ( 122 ). Additionally, EPF express a range of proteins to coat hyphal bodies, camouflaging their cell wall structures to further evade the host insect immunity ( 123 , 124 ).…”

Section: Fungal Penetration and Growth In Hemolymph And Insect Immune...mentioning

confidence: 99%

A life-and-death struggle: interaction of insects with entomopathogenic fungi across various infection stages

Ma,

Luo,

et al. 2024

Front. Immunol.

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Insects constitute approximately 75% of the world’s recognized fauna, with the majority of species considered as pests. Entomopathogenic fungi (EPF) are parasitic microorganisms capable of efficiently infecting insects, rendering them potent biopesticides. In response to infections, insects have evolved diverse defense mechanisms, prompting EPF to develop a variety of strategies to overcome or circumvent host defenses. While the interaction mechanisms between EPF and insects is well established, recent findings underscore that their interplay is more intricate than previously thought, especially evident across different stages of EPF infection. This review primarily focuses on the interplay between EPF and the insect defense strategies, centered around three infection stages: (1) Early infection stage: involving the pre-contact detection and avoidance behavior of EPF in insects, along with the induction of behavioral responses upon contact with the host cuticle; (2) Penetration and intra-hemolymph growth stage: involving the initiation of intricate cellular and humoral immune functions in insects, while symbiotic microbes can further contribute to host resistance; (3) Host insect’s death stage: involving the ultimate confrontation between pathogens and insects. Infected insects strive to separate themselves from the healthy population, while pathogens rely on the infected insects to spread to new hosts. Also, we discuss a novel pest management strategy underlying the cooperation between EPF infection and disturbing the insect immune system. By enhancing our understanding of the intricate interplay between EPF and the insect, this review provides novel perspectives for EPF-mediated pest management and developing effective fungal insecticides.

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“…This is due to the reduced number of studies related to immune responses and host defenses to pathogens prior to the 1990s. However, interest in this research area increased from 2012 to 2022, for example, Li et al (2021) described the mechanism of action of M. rileyi in relation to cellular immune responses in H. armigera, concluding that the mechanism by which entomopathogenic fungi escape host cellular immunity involves the inability of hosts to recognize hyphal bodies to induce a cellular immune response.…”

Section: Analysis Of Publication and Distribution Trends In Countriesmentioning

confidence: 99%

Bibliometric analysis of global research on fungal Metarhizium rileyi based on Web of Science

et al. 2022

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The use of microbial agents for pest control has been increasing gradually since the 1960s. Among these control agents, the fungus Metarhizium rileyi is responsible for causing epizootics in larvae of Lepidopteran pests. However, studies with this entomopathogen are relatively scarce when compared to other species, such as Beauveria bassiana and M. anisopliae. Thus, it is relevant to identify the research gaps. Our objective was to carry out a bibliometric survey of research involving M. rileyi. The data collection for bibliometric analysis was performed in the Web of Science Core Collection database, using the keywords M. rileyi and Nomuraea rileyi, resulting in a total of 329 articles from 1974 to October 2021. The literature on M. rileyi does not demonstrate a constant upward trend, revealing only two peaks of publications (1992 and 2018), with a maximum of 12 articles per year. Of the 329 articles, 65% were published before the 1990s, emphasizing that despite recent advances, the majority of articles corresponded to the period between 1974 and 1999. In addition, 77% of the publications are focused on pest control, highlighting the importance of the pathogen for biological control. However, there is a lack of work focused on the large‐scale production of the fungus, selective media for in vitro cultivation, the shelf life and environmental influence on conidia survival, application technology, formulations, and pathogen interaction with plants and insect hosts (trophic interaction).

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Mechanism of Metarhizium rileyi evading cellular immune responses in Helicoverpa armigera

Cited by 5 publications

References 46 publications

An entomopathogenic fungus exploits its host humoral antibacterial immunity to minimize bacterial competition in the hemolymph

An entomopathogenic fungus exploits its host humoral antibacterial immunity to minimize bacterial competition in the hemolymph

A life-and-death struggle: interaction of insects with entomopathogenic fungi across various infection stages

Bibliometric analysis of global research on fungal Metarhizium rileyi based on Web of Science

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