Cadophora margaritata sp. nov. and other fungi associated with the longhorn beetles Anoplophora glabripennis and Saperda carcharias in Finland

Symbiosis with microbes is crucial for survival and development of wood-inhabiting longhorn beetles (Coleoptera: Cerambycidae). Thus, knowledge of the endemic fungal associates of insects would facilitate risk assessment in cases where a new invasive pest occupies the same ecological niche. However, the diversity of fungi associated with insects remains poorly understood. The aim of this study was to investigate fungi associated with the native large poplar longhorn beetle (Saperda carcharias) and the recently introduced Asian longhorn beetle (Anoplophora glabripennis) infesting hardwood trees in Finland. We studied the cultivable fungal associates obtained from Populus tremula colonised by S. carcharias, and Betula pendula and Salix caprea infested by A. glabripennis, and compared these to the samples collected from intact wood material. This study detected a number of plant pathogenic and saprotrophic fungi, and species with known potential for enzymatic degradation of wood components. Phylogenetic analyses of the most commonly encountered fungi isolated from the longhorn beetles revealed an association with fungi residing in the Cadophora-Mollisia species complex. A commonly encountered fungus was Cadophora spadicis, a recently described fungus associated with wood-decay. In addition, a novel species of Cadophora, for which the name Cadophora margaritata sp. nov. is provided, was isolated from the colonised wood.Peer reviewe

Effects of the use of biocontrol agent ([i]Phlebiopsis gigantea[/i]) on fungal communities on the surface of [i]Picea abies[/i] stumps

One of the main objectives of sustainable forestry policies is to phase out, if possible, the use of chemical agents in forestry. The saprotrophic fungus Phlebiopsis gigantea has for several years been used as a biocontrol agent against the pathogen Heterobasidion annosum sensu lato. This pathogen is the major cause of root rot disease in conifers that results in economic losses estimated at 50 million euros to Finnish forestry industry annually. A major problem is that, although the effectiveness of P. gigantea as a bin-control agent has empirically been shown, the long term biological effect of this fungus on conifer trees as well as on other wood microflora has not been empirically proven. We investigated the impact of P. gigantea treatment on stump mycobiota using 454-pyrosequencing approach as this has not done before. Samples from forest sites pre-treated with P. gigantea for I, 6 and 13 years ago were collected, DNA was isolated and the ITS regions were pyrosequenced. Similarly samples were also collected from untreated stumps within the same forest site over the same period of time. A total of 53,117 fungal sequences were generated by 454-pyrosequencing from 18 wood samples. After data cleaning we had 26,127 sequences representing 49% of the original sequences. Possible impact of the treatment on fungal communities in different study sites was analyzed using Principal Component Analysis (PCA). Also diversity indexes and similarity indexes between controls and treated stumps were calculated. Biocontrol P. gigantea represented 0.43% of all fungal sequences and was found only from stumps after one year post-treatment. The pathogen H. annosum s.l. was not observed in this study. Numbers of different OTUs were always higher in the control stumps. However there was no statistical difference noted between treated and non-treated stumps. Based on our results we can conclude that stump treatment should continue as there is no obvious adverse effect on the other stump mycobiota

Dominant tree species and soil type affect fungal community structure in a boreal peatland forest

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Viral molecular mimicry influences the antitumor immune response in murine and human melanoma

Molecular mimicry is one of the leading mechanisms by which infectious agents can induce autoimmunity. Whether a similar mechanism triggers an antitumor immune response is unexplored, and the role of antiviral T cells infiltrating the tumor has remained anecdotal. To address these questions, we first developed a bioinformatic tool to identify tumor peptides with high similarity to viral epitopes. Using peptides identified by this tool, we demonstrated that, in mice, preexisting immunity toward specific viral epitopes enhanced the efficacy of cancer immunotherapy via molecular mimicry in different settings. To understand whether this mechanism could partly explain immunotherapy responsiveness in humans, we analyzed a cohort of patients with melanoma undergoing anti-PD1 treatment who had a high IgG titer for cytomegalovirus (CMV). In this cohort of patients, we showed that high levels of CMV-specific antibodies were associated with prolonged progression-free survival and found that, in some cases, peripheral blood mononuclear cells (PBMC) could cross-react with both melanoma and CMV homologous peptides. Finally, T-cell receptor sequencing revealed expansion of the same CD8þ T-cell clones when PBMCs were expanded with tumor or homologous viral peptides. In conclusion, we have demonstrated that preexisting immunity and molecular mimicry could influence the response to immunotherapies. In addition, we have developed a free online tool that can identify tumor antigens and neoantigens highly similar to pathogen antigens to exploit molecular mimicry and cross-reactive T cells in cancer vaccine development

Viral molecular mimicry influences the antitumor immune response in murine and human melanoma

Molecular mimicry is one of the leading mechanisms by which infectious agents can induce autoimmunity. Whether a similar mechanism triggers an antitumor immune response is unexplored, and the role of antiviral T cells infiltrating the tumor has remained anecdotal. To address these questions, we first developed a bioinformatic tool to identify tumor peptides with high similarity to viral epitopes. Using peptides identified by this tool, we demonstrated that, in mice, preexisting immunity toward specific viral epitopes enhanced the efficacy of cancer immunotherapy via molecular mimicry in different settings. To understand whether this mechanism could partly explain immunotherapy responsiveness in humans, we analyzed a cohort of patients with melanoma undergoing anti-PD1 treatment who had a high IgG titer for cytomegalovirus (CMV). In this cohort of patients, we showed that high levels of CMV-specific antibodies were associated with prolonged progression-free survival and found that, in some cases, peripheral blood mononuclear cells (PBMC) could cross-react with both melanoma and CMV homologous peptides. Finally, T-cell receptor sequencing revealed expansion of the same CD8þ T-cell clones when PBMCs were expanded with tumor or homologous viral peptides. In conclusion, we have demonstrated that preexisting immunity and molecular mimicry could influence the response to immunotherapies. In addition, we have developed a free online tool that can identify tumor antigens and neoantigens highly similar to pathogen antigens to exploit molecular mimicry and cross-reactive T cells in cancer vaccine development.publishedVersionPeer reviewe

Single-cell characterization of anti–LAG-3 and anti–PD-1 combination treatment in patients with melanoma

Abstract Background: Relatlimab plus nivolumab (anti–lymphocyte-activation gene 3 plus anti–programmed death 1 [anti–LAG-3+anti–PD-1]) has been approved by the FDA as a first-line therapy for stage III/IV melanoma, but its detailed effect on the immune system is unknown. Methods: We evaluated blood samples from 40 immunotherapy-naive or prior immunotherapy–refractory patients with metastatic melanoma treated with anti–LAG-3+anti–PD-1 in a phase I trial using single-cell RNA and T cell receptor sequencing (scRNA+TCRαβ-Seq) combined with other multiomics profiling. Results: The highest LAG3 expression was noted in NK cells, Tregs, and CD8⁺ T cells, and these cell populations underwent the most significant changes during the treatment. Adaptive NK cells were enriched in responders and underwent profound transcriptomic changes during the therapy, resulting in an active phenotype. LAG3⁺ Tregs expanded, but based on the transcriptome profile, became metabolically silent during the treatment. Last, higher baseline TCR clonality was observed in responding patients, and their expanding CD8⁺ T cell clones gained a more cytotoxic and NK-like phenotype. Conclusion: Anti–LAG-3+anti–PD-1 therapy has profound effects on NK cells and Tregs in addition to CD8⁺ T cells. Trial registration: ClinicalTrials.gov (NCT01968109) Funding : Cancer Foundation Finland, Sigrid Juselius Foundation, Signe and Ane Gyllenberg Foundation, Relander Foundation, State funding for university-level health research in Finland, a Helsinki Institute of Life Sciences Fellow grant, Academy of Finland (grant numbers 314442, 311081, 335432, and 335436), and an investigator-initiated research grant from BMS