Changes in parasite virulence are commonly expected to lead to trade-offs in other life history traits that can affect fitness. Understanding these trade-offs is particularly important if we want to manipulate the virulence of microbial biological control agents. Theoretically, selection across different spatial scales, i.e. between- and within-hosts, shapes these trade-offs. However, trade-offs are also dependent on parasite biology. Despite their applied importance the evolution of virulence in fungal parasites is poorly understood: virulence can be unstable in culture and commonly fails to increase in simple passage experiments. We hypothesized that manipulating selection intensity at different scales would reveal virulence trade-offs in a fungal pathogen of aphids, Akanthomyces muscarius. Starting with a genetically diverse stock we selected for speed of kill, parasite yield or infectivity by manipulating competition within and between hosts and between-populations of hosts over 7 rounds of infection. We characterized ancestral and evolved lineages by whole genome sequencing and by measuring virulence, growth rate, sporulation and fitness. While several lineages showed increases in virulence, we saw none of the trade-offs commonly found in obligately-killing parasites. Phenotypically similar lineages within treatments often shared multiple single-nucleotide variants, indicating strong convergent evolution. The most dramatic phenotypic changes were in timing of sporulation and spore production in vitro. We found that early sporulation led to reduced competitive fitness but could increase yield of spores on media, a trade-off characteristic of social conflict. Notably, the selection regime with strongest between-population competition and lowest genetic diversity produced the most consistent shift to early sporulation, as predicted by social evolution theory. Multi-level selection therefore revealed social interactions novel to fungi and showed that these biocontrol agents have the genomic flexibility to improve multiple traits-virulence and spore production-that are often in conflict in other parasites.
Aphids , Parasites , Animals , Biological Evolution , Phenotype , Host-Parasite Interactions/genetics
Fialuridine (FIAU) is a nucleoside-based drug that caused liver failure and deaths in a human clinical trial that were not predicted by nonclinical safety studies. A recent report concluded that a TK-NOG humanized liver (hu-liver) mouse model detected human-specific FIAU liver toxicity, and broader use of that model could improve drug safety testing. We further evaluated this model at similar dose levels to assess FIAU sensitivity and potential mechanistic biomarkers. Although we were unable to reproduce the marked acute liver toxicity with two separate studies (including one with a "sensitized" donor), we identified molecular biomarkers reflecting the early stages of FIAU mitochondrial toxicity, which were not seen with its stereoisomer (FIRU). Dose dependent FIAU-induced changes in hu-liver mice included more pronounced reductions in mitochondrial to nuclear DNA (mtDNA/nucDNA) ratios in human hepatocytes compared to mouse hepatocytes and kidneys of the same animals. FIAU treatment also triggered a p53 transcriptional response and opposing changes in transcripts of nuclear- and mitochondrial-encoded mitochondrial proteins. The time dependent accumulation of FIAU into mtDNA is consistent with the ≥9-week latency of liver toxicity observed for FIAU in the clinic. Similar changes were observed in an in vitro micro-patterned hepatocyte coculture system. In addition, FIAU-dependent mtDNA/nucDNA ratio and transcriptional alterations, especially reductions in mitochondrially encoded transcripts, were seen in livers of non-engrafted TK-NOG and CD-1 mice dosed for a shorter period. Conclusion: These mechanistic biomarker findings can be leveraged in an in vitro model and in a more routine preclinical model (CD-1 mice) to identify nucleosides with such a FIAU-like mitochondrial toxicity mechanistic liability potential. Further optimization of the TK-NOG hu-liver mouse model is necessary before broader adoption for drug safety testing.
The entomopathogenic fungus Akanthomyces muscarius is commonly used in agriculture to manage insect pests. Besides its use as a commercially important biological control agent, it also presents a potential model for studying host-pathogen interactions and the evolution of virulence in a laboratory setting. Here, we describe the first high-quality genome sequence for A. muscarius. We used long- and short-read sequencing to assemble a sequence of 36.1 Mb with an N50 of 4.9 Mb. Genome annotation predicted 12347 genes, with 96.6â% completeness based on the core Hypocrealen gene set. The high-quality assembly and annotation of A. muscarius presented in this study provides an essential tool for future research on this commercially important species.
Drug-induced pancreatic injury (DIPI) is an issue seen in drug development both in nonclinical and clinical contexts. DIPI is typically monitored by measurement of lipase and/or amylase, however, both enzymes lack sensitivity and specificity. Although candidate protein biomarkers specific to pancreas exist, antibody-based assay development is difficult due to their small size or the rapid cleavage by proteolytic enzymes released during pancreatic injury. Here we report the development of a novel multiplexed immunoaffinity-based liquid chromatography mass spectrometric assay (IA-LC-MS/MS) for trypsinogen activation peptide (TAP) and carboxypeptidases A1 and A2 (CPA1, CPA2). This method is based on the enzymatic digestion of the target proteins, immunoprecipitation of the peptides with specific antibodies and LC-MS/MS analysis. This assay was used to detect TAP, CPA1, and CPA2 in 470 plasma samples collected from 9 in-vivo rat studies with pancreatic injury and 8 specificity studies with injury in other organs to assess their performance in monitoring exocrine pancreas injury. The TAP, CPA1, and CPA2 response was compared to histopathology, lipase, amylase and microRNA217. In summary, TAP, CPA1, and CPA2 proteins measured in rat plasma were sensitive and specific biomarkers for monitoring drug-induced pancreatic injury; outperforming lipase and amylase both by higher sensitivity of detection and by sustained increases in plasma observed over a longer time period. These protein-based assays and potentially others under development, are valuable tools for use in nonclinical drug development and as future translatable biomarkers for assessment in clinical settings to further improve patient safety.
Amylases , Tandem Mass Spectrometry , Rats , Animals , Chromatography, Liquid/methods , Tandem Mass Spectrometry/methods , Carboxypeptidases A/metabolism , Biomarkers , Lipase
Understanding the ecological and genetic factors that determine the evolution of virulence has broad value for invertebrate pathology. In addition to helping us understand the fundamental biology of our study organisms this body of theory has important applications in microbial biocontrol. Experimental tests of virulence theory are often carried out in invertebrate models and yet theory rarely informs applied passage experiments that aim to increase or maintain virulence. This review summarizes recent progress in this field with a focus on work most relevant to biological control: the virulence of invertebrate pathogens that are 'obligate killers' and which require cadavers for the production of infectious propagules. We discuss recent theory and fundamental and applied experimental evolution with bacteria, fungi, baculoviruses and nematodes. While passage experiments using baculoviruses have a long history of producing isolates with increased virulence, studies with other pathogens have not been so successful. Recent passage experiments that have applied evolution of virulence frameworks based on cooperation (kin selection) have produced novel methods and promising mutants with increased killing power. Evolution of virulence theory can provide plausible explanations for the varied results of passage experiments as well as a predictive framework for improving artificial selection.
Biological Evolution , Nematoda , Animals , Baculoviridae , Fungi/genetics , Virulence
BACKGROUND: Biological control is a cornerstone of integrated pest management and could also play a key role in managing the evolution of insecticide resistance. Ecological theory predicts that the fitness cost of insecticide resistance can be increased under exposure to invertebrate natural enemies or pathogens, and can therefore increase the value of integrating biological control into pest management. In this study of the peach potato aphid, Myzus persicae, we aimed to identify whether insecticide resistance affected fitness and vulnerability of different aphid clones to the entomopathogenic fungus Akanthomyces muscarius. RESULTS: Insecticide resistant clones were found to be slightly less susceptible to the pathogen than susceptible clones. However, this pattern could also be explained by the influence of length of laboratory culture, which was longer in susceptible clones and was positively correlated with susceptibility to fungi. Furthermore, resistance status did not affect aphid development time or intrinsic rate of increase of aphids. Finally, in a cage trial the application of fungus did not increase the competitive fitness of insecticide resistant clone 'O'. CONCLUSION: We found no fitness cost in reproductive rate or pathogen susceptibility associated with chemical resistance in M. persicae. In contrast, some susceptible clones, particularly those subject to decades of laboratory rearing, showed enhanced susceptibility to a fungal pathogen, but not reduced reproductive fitness, an observation consistent with down-regulation of costly immune functions in culture. Overall, fungal pathogen control is compatible with insecticides and should not increase the selection pressure for resistance of M. persicae to chemical insecticides.
Aphids , Hypocreales , Insecticides , Animals , Clone Cells , Insecticide Resistance/genetics , Insecticides/pharmacology
A new safety testing paradigm that relies on gene expression biomarker panels was developed to easily and quickly identify drug-induced injuries across tissues in rats prior to drug candidate selection. Here, we describe the development, qualification, and implementation of gene expression signatures that diagnose tissue degeneration/necrosis for use in early rat safety studies. Approximately 400 differentially expressed genes were first identified that were consistently regulated across 4 prioritized tissues (liver, kidney, heart, and skeletal muscle), following injuries induced by known toxicants. Hundred of these "universal" genes were chosen for quantitative PCR, and the most consistent and robustly responding transcripts selected, resulting in a final 22-gene set from which unique sets of 12 genes were chosen as optimal for each tissue. The approach was extended across 4 additional tissues (pancreas, gastrointestinal tract, bladder, and testes) where toxicities are less common. Mathematical algorithms were generated to convert each tissue's 12-gene expression values to a single metric, scaled between 0 and 1, and a positive threshold set. For liver, kidney, heart, and skeletal muscle, this was established using a training set of 22 compounds and performance determined by testing a set of approximately 100 additional compounds, resulting in 74%-94% sensitivity and 94%-100% specificity for liver, kidney, and skeletal muscle, and 54%-62% sensitivity and 95%-98% specificity for heart. Similar performance was observed across a set of 15 studies for pancreas, gastrointestinal tract, bladder, and testes. Bundled together, we have incorporated these tissue signatures into a 4-day rat study, providing a rapid assessment of commonly seen compound liabilities to guide selection of lead candidates without the necessity to perform time-consuming histopathologic analyses.
Gene Expression Profiling , Pharmaceutical Preparations , Animals , Liver , Rats , Risk Assessment , Transcriptome
Drug-induced pancreatic injury (DIPI) has become linked in recent years to many commonly prescribed medications from several pharmacological classes. Diagnosis is currently most often focused on identification of acute pancreatitis and generally based on subjective clinical assessment and serum amylase and lipase enzymatic activity, which have been criticized as being insufficiently sensitive and specific. The lack of novel noninvasive biomarkers of DIPI can impede the advancement of drug candidates through nonclinical development and translation into clinical settings. Pancreas-specific microRNAs (miRNAs) are currently being evaluated as biomarkers of DIPI that may outperform and/or add value to the interpretation of amylase and lipase. To assess the relative performance of these novel miRNAs, a comprehensive evaluation was conducted to determine the sensitivity and specificity of detecting DIPI in rats. Four miRNAs were evaluated (miR-216a-5p, miR-216b-5p, miR-217-5p, and miR-375-3p) in plasma from 10 studies in which rats were treated with known pancreatic toxicants to assess sensitivity, and from 10 different studies in which toxicity was evident in tissues other than pancreas to assess specificity. The candidate miRNA biomarker performance was compared with amylase and lipase, and receiver operator characteristics (ROC) were determined. Analysis of ROCs demonstrated that all four miRNAs outperformed amylase and lipase in monitoring acute pancreatic injury defined as acinar cell degeneration/necrosis. Specifically, miR-217-5p had the highest performance among all biomarkers assessed. The increased sensitivity and specificity of these miRNAs support their use as biomarkers of DIPI, thereby adding value to the interpretation of amylase and lipase measurements in nonclinical studies. The potential for miRNAs to serve as translational biomarkers in the clinic for the monitoring of DIPI is also supported by this investigation.
MicroRNAs/blood , Pancreatitis/blood , Acinar Cells , Acute Disease , Amylases , Animals , Biomarkers/blood , Disease Models, Animal , Female , Gene Expression Profiling , Lipase , Male , Pancreas , Plasma , Rats
Liver and skeletal muscle-specific microRNAs (miRNAs) are currently being evaluated as novel plasma biomarkers that may out-perform or add value to the conventional liver injury biomarkers alanine aminotransferase (ALT) and aspartate aminotransferase (AST), and to the skeletal muscle injury biomarkers AST and creatine kinase (CK). A comprehensive evaluation was conducted to assess the relative performance of these miRNAs to detect and distinguish liver from muscle tissue injury. The performance of miR-122 and miR-192 for liver and miR-1, miR-133a, miR-133b, and miR-206 for skeletal muscle was compared with 10 enzymatic or protein biomarkers across 27 compounds causing specific types of tissue injury in rat. Receiver operator characteristic analyses were performed comparing the relative sensitivity and specificity of each of the biomarkers in individual animals with histopathology observations of necrosis and/or degeneration in various organs. All of the miRNAs outperformed ALT, AST, and/or CK in studies with either liver or skeletal muscle injury and demonstrated superior specificity in organs without type-specific injury (eg, liver biomarkers assessed with compounds that cause skeletal muscle injury). When additional protein biomarkers were included, glutamate dehydrogenase, arginase I, alpha-glutathione S-transferase for liver and skeletal troponin I, myosin light chain 3, fatty acid-binding protein 3, and creatine kinase M isoform for skeletal muscle, the miRNAs demonstrated equal or superior performance to the extended panel. Taken together, this comprehensive evaluation demonstrates that these novel miRNA toxicity biomarkers outperform and add value with respect to sensitivity and specificity over ALT, AST in monitoring the liver and over CK for monitoring skeletal muscle drug-induced injury.
Chemical and Drug Induced Liver Injury/diagnosis , Liver/metabolism , MicroRNAs/blood , Muscle, Skeletal/metabolism , Muscular Diseases/diagnosis , Alanine Transaminase/blood , Animals , Aspartate Aminotransferases/blood , Biomarkers/blood , Chemical and Drug Induced Liver Injury/blood , Creatine Kinase, MM Form/blood , Female , Male , Muscular Diseases/blood , Muscular Diseases/chemically induced , Rats , Rats, Sprague-Dawley , Rats, Wistar
The conclusions of EFSA following the peer review of the initial assessments carried out by the competent authorities of the rapporteur Member State, the United Kingdom, and co-rapporteur Member State, Austria, for the pesticide active substance quinoxyfen are reported. The context of the peer review was that required by Commission Implementing Regulation (EU) No 844/2012. The conclusions were reached on the basis of the evaluation of information targeted at the assessment of the potential persistent, bioaccumulative and toxic (PBT), very persistent and very bioaccumulative (vPvB) and persistent organic pollutant (POP) properties of quinoxyfen according to Article 11(2) of Regulation (EC) No 1107/2009. The reliable end points, appropriate for use in these regulatory hazard cut off assessments are presented. Missing information identified as being required by the regulatory framework is listed. The concern is identified that quinoxyfen may be considered to exhibit the hazard properties of both a PBT and vPvB substance considering the triggers specified in Annex II of Regulation (EC) No 1107/2009.
In accordance with Article 53 of Regulation (EC) 1107/2009, the United Kingdom granted a 120-day emergency authorisation for the use of cyantraniliprole in leek. In order to accommodate for the new use, the Agriculture & Horticulture Development Board submitted an application to raise the existing maximum residue level (MRL) for the crop concerned. The United Kingdom, as evaluating Member State, summarised the data provided by the applicant in an evaluation report which was submitted to the European Commission and forwarded to EFSA. Sufficient residue trials are available to derive an MRL proposal of 0.6 mg/kg for leeks in accordance with the emergency authorised good agricultural practice (GAP). Adequate analytical methods for enforcement are available to control the residues of cyantraniliprole in the commodities under consideration. Based on the risk assessment results, EFSA concluded that intake of residues resulting from the use of cyantraniliprole according to the reported agricultural practice is unlikely to present a risk to consumer health.
The conclusions of EFSA following the peer review of the initial risk assessments carried out by the competent authorities of the rapporteur Member State, the Netherlands, and co-rapporteur Member State, Belgium, for the pesticide active substance chlorothalonil are reported. The context of the peer review was that required by Commission Implementing Regulation (EU) No 844/2012. The conclusions were reached on the basis of the evaluation of the representative uses of chlorothalonil as a fungicide on wheat, barley, tomato and potato. The reliable endpoints, appropriate for use in regulatory risk assessment, are presented. Missing information identified as being required by the regulatory framework is listed. Concerns are identified.
In accordance with Article 6 of Regulation (EC) No 396/2005, the evaluating Member State (EMS), France, received an application from BASF SE to modify the existing maximum residue level (MRL) for the active substance metazachlor in Chinese cabbage. To accommodate for the intended use of metazachlor, France proposed to raise the existing MRL from the value of 0.2 mg/kg to 0.6 mg/kg. France drafted an evaluation report in accordance with Article 8 of Regulation (EC) No 396/2005, which was submitted to the European Commission and forwarded to EFSA. According to EFSA, the data are sufficient to derive a MRL proposal of 0.6 mg/kg for the proposed use on Chinese cabbage. Adequate analytical enforcement methods are available to control the residues of metazachlor on the commodity under consideration. Based on the risk assessment results, EFSA concludes that the proposed use of metazachlor on Chinese cabbage will not result in a consumer exposure exceeding the toxicological reference values and therefore is unlikely to pose a consumer health risk.
In accordance with Article 6 of Regulation (EC) No 396/2005, the applicant Bayer CropScience AG submitted a request to the competent national authority in Greece to set import tolerances for the active substance flubendiamide in apricots, peaches, nectarines, plums and soya beans. The data submitted in support of the request were found to be sufficient to derive maximum residue level (MRL) proposals for apricots, peaches/nectarines, plums. For soya beans, further risk management considerations are required to decide the import tolerance to be set. Adequate analytical methods for enforcement are available to control the residues of flubendiamide in plant matrices. Based on the risk assessment results, EFSA concluded that the short-term and long-term intake of residues resulting from the use of flubendiamide according to the reported agricultural practices is unlikely to present a risk to consumer health.
The conclusions of the EFSA following the peer review of the initial risk assessments carried out by the competent authorities of the rapporteur Member State, Sweden, and co-rapporteur Member State, Denmark, for the pesticide active substance tolclofos-methyl are reported. The context of the peer review was that required by Commission Implementing Regulation (EU) No 844/2012. The conclusions were reached on the basis of the evaluation of the representative uses of tolclofos-methyl as a fungicide on potatoes, lettuce and ornamentals. The reliable end points, appropriate for use in regulatory risk assessment, are presented. Missing information identified as being required by the regulatory framework is listed. Concerns are identified.
The conclusions of the EFSA following the peer review of the initial risk assessments carried out by the competent authorities of the rapporteur Member State, Sweden, and co-rapporteur Member State, Finland, for the pesticide active substance thiophanate-methyl are reported. The context of the peer review was that required by Commission Implementing Regulation (EU) No 844/2012. The conclusions were reached on the basis of the evaluation of the representative uses of thiophanate-methyl as a fungicide on wine grapes, tomato, aubergine, leek, fresh beans with pods and wheat (winter and durum). The reliable endpoints, appropriate for use in regulatory risk assessment, are presented. Missing information identified as being required by the regulatory framework is listed. Concerns are identified.
In accordance with Article 6 of Regulation (EC) No 396/2005, the competent national authority in Belgium sent an application to modify the existing maximum residue level (MRL) for the active substance fluopicolide in chards. In order to accommodate for the intended use of fluopicolide, the evaluating Member State (EMS) proposed to raise the existing MRLs from 4 mg/kg to 6 mg/kg. Belgium drafted the evaluation report in accordance with Article 8 of Regulation (EC) No 396/2005, which was submitted to the European Commission and forwarded to EFSA. According to EFSA, the data are sufficient to derive a MRL proposal of 6 mg/kg on chards. Adequate analytical enforcement methods are available to control the residues of fluopicolide in chards at the validated limit of quantification (LOQ) of 0.01 mg/kg. Based on the risk assessment results, EFSA concluded that the proposed use of fluopicolide on chards will not result in a consumer exposure exceeding the toxicological reference values and therefore is unlikely to pose a consumer health risk.
The conclusions of EFSA following the peer review of the initial risk assessments carried out by the competent authorities of the rapporteur Member State, France, and co-rapporteur Member State, Spain, for the pesticide active substance indoxacarb are reported. The context of the peer review was that required by Commission Implementing Regulation (EU) No 844/2012. The conclusions were reached on the basis of the evaluation of the representative uses of indoxacarb as an insecticide on maize, sweet corn and lettuce. The reliable endpoints, appropriate for use in regulatory risk assessment, are presented. Missing information identified as being required by the regulatory framework is listed. Concerns are identified.
According to Article 12 of Regulation (EC) No 396/2005, EFSA has reviewed the maximum residue levels (MRLs) currently established at European level for the pesticide active substance bispyribac. To assess the occurrence of bispyribac residues in plants, processed commodities, rotational crops and livestock, EFSA considered the conclusions derived in the framework of Directive 91/414/EEC as well as the European authorisations reported by Member States (including the supporting residues data). Based on the assessment of the available data, MRL proposals were derived and a consumer risk assessment was carried out. All information required by the regulatory framework was present and a risk to consumers was not identified.
In accordance with Article 6 of Regulation (EC) No 396/2005, the applicant BASF SE submitted a request to the competent national authority in the United Kingdom to modify the existing maximum residue levels (MRLs) for the active substance difenoconazole in various crops. The data submitted in support of the request were found to be sufficient to derive MRL proposals for all crops under consideration. Adequate analytical methods for enforcement are available to control the residues of difenoconazole in plant matrices under consideration. The estimated long-term and short-term intake to residues of difenoconazole resulting from the existing and the intended uses did not exceed the toxicological reference values established for the active substance difenoconazole. The consumer exposure assessment has to be considered provisional as the impact of a potentially different isomer composition in the residues of difenoconazole on this risk assessment is currently unknown and has to be reconsidered when data on possible preferential metabolism/degradation of the four stereo isomers of difenoconazole in plants is available and guidance on a risk assessment approach for residues containing isomers is implemented.
