Discovery and genomic characterization of three double-stranded RNA viruses coinfecting Conidiobolus taihushanensis.

Conidiobolus sensu lato, a genus within the family Ancylistaceae, encompasses a diverse range of fungal species that are widely distributed in plant debris and soil. In this study, we identified three double-stranded RNA (dsRNA) viruses coinfecting a strain of Conidiobolus taihushanensis. These viruses were identified as Conidiobolus taihushanensis totivirus 1 (CtTV1), Conidiobolus nonsegmented RNA virus 1-2 (CNRV1-2), and Conidiobolus taihushanensis virus 1 (CtV1). Through high-throughput sequencing and RNA-ligase-mediated rapid amplification of cDNA ends (RLM-RACE), we determined their complete genome sequences. The genome of CtTV1 is 6,921 nucleotides in length, containing two open reading frames (ORFs). ORF1 encodes a 1,124-amino-acid capsid protein (CP) with a molecular weight of 125.07 kDa, and ORF2 encodes a 780-amino-acid RNA-dependent RNA polymerase (RdRp) with a molecular weight of 88.05 kDa. CNRV1-2, approximately 3.0 kb in length, also contains two ORFs, which are predicted to encode a 186-amino-acid hypothetical protein (HP) and a 758-amino-acid RdRp. CtV1 has a smaller genome consisting of 3,081 base pairs (bp) with two ORFs: one encoding a 244-amino-acid HP (26.85 kDa) and the other encoding a 707-amino-acid RdRp (80.64 kDa). Phylogenetic analysis based on RdRp sequences revealed that CtTV1 shows the highest similarity to Phytophthora pluvialis RNA virus 1, with 38.79% sequence identity, and clusters with members of the family Orthototiviridae, and it is most closely related to Utsjoki toti-like virus. In contrast, CtV1 formed a unique branch and might represent a new genus. The genome sequence of CNRV1-2 is 99.74% identical to that of the previously described Conidiobolus non-segmented RNA virus 1 (CNRV1). Our findings indicate that CtTV1 and CtV1 are distinct novel viruses, while CNRV1-2 appears to be a variant of CNRV1. This study enhances our understanding of the genetic diversity and evolutionary relationships among mycoviruses associated with C. taihushanensis.

Molecular characterization of two novel totiviruses coinfecting the basal fungus Conidiobolus adiaeretus.

A number of viruses have recently been discovered in all major fungal phyla using high-throughput sequencing. However, basal fungi remain among the least-explored organisms with respect to the presence of mycoviruses. In this study, we characterized two mycoviruses coinfecting the basal fungus Conidiobolus adiaeretus, which we have named "Conidiobolus adiaeretus totivirus 1" (CaTV1) and "Conidiobolus adiaeretus totivirus 2" (CaTV2). Due to their similar sizes, the genomic RNAs of these two viruses comigrated as a single band in 1.5% agarose gel electrophoresis but could be distinguished and characterized by next-generation sequencing and RT-PCR. Like those of other totiviruses, the genomes of both CaTV1 and CaTV2 have two discontinuous open reading frames: ORF1 and ORF2, encoding a putative capsid protein and a putative RNA-dependent RNA polymerase (RdRp), respectively. The RdRps of CaTV1 and CaTV2 have 62.73% and 63.76% amino acid sequence identity, respectively, to Wuhan insect virus 26 and have 62.15% amino acid sequence identity to each other. A maximum-likelihood phylogenetic tree based on RdRp amino acid sequences showed that both CaTV1 and CaTV2 clustered in a clade with members of the genus Totivirus. Therefore, we propose that CaTV1 and CaTV2 are two new members of the genus Totivirus in the family Totiviridae.

Pediatric case of conidiobolomycosis: A rare entity.

Conidiobolomycosis caused by Conidiobolus species is an uncommon infection restricted to tropical and subtropical regions, usually affecting immunocompetent individuals. More than half of pediatric cases of conidiobolomycosis across the globe are from India. We report a case of subcutaneous conidiobolomycosis in an adolescent with development delay who responded to combined therapy with itraconazole and saturated solution of potassium iodide.

Octanoic Acid-An Insecticidal Metabolite of Conidiobolus coronatus (Entomopthorales) That Affects Two Majors Antifungal Protection Systems in Galleria mellonella (Lepidoptera): Cuticular Lipids and Hemocytes.

The food flavour additive octanoic acid (C8:0) is also a metabolite of the entomopathogenic fungus Conidiobolus coronatus, which efficiently infects and rapidly kills Galleria mellonella. GC-MS analysis confirmed the presence of C8:0 in insecticidal fraction FR3 extracted from C. coronatus filtrate. Topical administration of C8:0 had a dose-dependent effect on survival rates of larvae but not on pupation or adult eclosion times of the survivors. Topically applied C8:0 was more toxic to adults than larvae (LD100 for adults 18.33 ± 2.49 vs. 33.56 ± 2.57 µg/mg of body mass for larvae). The administration of C8:0 on the cuticle of larvae and adults, in amounts corresponding to their LD50 and LD100 doses, had a considerable impact on the two main defense systems engaged in protecting against pathogens, causing serious changes in the developmental-stage-specific profiles of free fatty acids (FFAs) covering the cuticle of larvae and adults and damaging larval hemocytes. In vitro cultures of G. mellonella hemocytes, either directly treated with C8:0 or taken from C8:0 treated larvae, revealed deformation of hemocytes, disordered networking, late apoptosis, and necrosis, as well as caspase 1-9 activation and elevation of 8-OHdG level. C8:0 was also confirmed to have a cytotoxic effect on the SF-9 insect cell line, as determined by WST-1 and LDH tests.

Molecular characterization of a novel totivirus infecting the basal fungus Conidiobolus heterosporus.

Mycoviruses are widely distributed in fungi, but only a few mycoviruses have been reported in basal fungi to date. Here, we characterized a novel totivirus isolated from the basal fungus Conidiobolus heterosporus, and we designated this virus as "Conidiobolus heterosporus totivirus 1" (ChTV1). The complete genome of ChTV1 contains two discontinuous open reading frames (ORFs), ORF1 and ORF2, encoding a putative coat protein (CP) and a putative RNA-dependent RNA polymerase (RdRP), respectively. Phylogenetic analysis based on RdRP sequences showed that ChTV1 clustered with members of the genus Totivirus. The RdRP of ChTV1 has 51% sequence identity to that of Trichoderma koningiopsis totivirus 1 (TkTV1), which is the highest among mycoviruses. However, TkTV1 formed a distinct cluster with Wuhan insect virus 27, with 63% RdRP sequence identity, although Wuhan insect virus 27 has not been described, and its host represents a different kingdom. Therefore, we propose that ChTV1 is a new member of the genus Totivirus, family Totiviridae.

Rhinofacial conidiobolomycosis: Clinical and microbiological characterisation and shift in the management of a rare disease.

BACKGROUND: Conidiobolomycosis is a rare tropical rhinofacial fungal infection which has not been well characterised. The available evidence in its management is sparse due to lack of clinical studies and the limited data on antifungal susceptibility patterns. OBJECTIVE: To analyse the clinical manifestations, antifungal treatment and outcomes of patients with conidiobolomycosis and to determine antifungal susceptibility profiles of the isolates. PATIENTS/METHODS: Retrospective analysis of data of all patients with a diagnosis of conidiobolomycosis confirmed by histopathology and culture at a tertiary care hospital from 2012 to 2019 was done. RESULTS: There were 22 patients, 21 males and one female, with a mean age of 37.1 years. Most common presenting symptom was nasal obstruction, found in 20 (90.90%) patients. Patients who presented within 12 months had a better cure rate (85%) compared to those who presented late (67%). Among the 19 patients who had a follow-up, good outcome was seen in 15 of the 17 (88.24%) patients who were on itraconazole or potassium iodide containing regimen. Of the six patients who received additional trimethoprim-sulphamethoxazole (co-trimoxazole), 67% showed good outcome with two patients showing complete cure and two patients still on treatment with significant improvement. High minimum inhibitory concentration (MIC) values were noted for azoles and amphotericin B, whereas co-trimoxazole showed lowest MIC ranges. CONCLUSION: Itraconazole and potassium iodide are reasonable first-line options for the treatment of conidiobolomycosis. Good clinical response to KI and comparatively lower MIC of co-trimoxazole are promising. Further studies are required for developing clinical breakpoints that can predict therapeutic outcomes.

Conidiobolus lunulus, a newly discovered entomophthoralean species, pathogenic and specific to leaf-cutter ants.

Conidiobolus lunulus is a recently described entomophthoralean species isolated from leaf-cutter ants. This fungus discharges not only primary but also secondary conidia and microconidia of different shapes. Because nothing was known about the biology of the fungus, and its interactions with hosts, we first evaluated if its pathogenicity against leaf-cutter ants changes with the fungal age (time grown in vitro), and if it is related to the conidial structures produced. Afterwards, we tested its virulence at three combinations of temperature and relative humidity. In addition, we noted all visible causes of death by recovering different microorganisms from the dead, non-sterilized, ants to evaluate C. lunulus virulence when pathogens carried naturally by the ants were present. Finally, we used the conditions that lead to the highest mortality to evaluate fungal virulence to other host species, including non-leaf-cutter ants. Results indicated that C. lunulus was pathogenic from a culture age of 1 to 5 days, with a peak at 2-days-old, from which we registered median lethal times of 1-2 days and 85% of the cadavers with fungal conidiation. Our results suggest that primary conidia and moon-shaped microconidia were infective. Evaluations of mortality using 2-days-old cultures on several leaf-cutter ant colonies showed 1) significantly faster mortality of C. lunulus inoculated ants in comparison to controls, 2) significantly greater and faster mortality at 23.7 °C than at 21.2 °C, 3) significantly higher and faster mortality at 88% than at 57% RH, and 4) a significant reduction of other pathogens in C. lunulus inoculated ants in comparison to controls. C. lunulus was highly specific to leaf-cutter ants, as hardly any increase in mortality was observed on inoculated ants, and no conidia were recorded on cadavers of the other three non-leaf-cutter ant species tested. Our results highlight that C. lunulus is a very promising biological control agent against leaf-cutter ants.

A novel non-segmented double-stranded RNA virus isolated from the basal fungus Conidiobolus sp.

Mycoviruses are widely distributed in a variety of fungal species. However, few viruses have been reported in basal fungi. A novel non-segmented dsRNA virus was isolated from the basal fungus Conidiobolus sp. of the phylum Zoopagomycota, which has been named "Conidiobolus non-segmented RNA virus 1" (CNRV1). The complete genome sequence of CNRV1 was determined by dsRNA extraction, next-generation sequencing, and RACE. The genome of CNRV1 dsRNA is 3,092 bp in length and contains two open reading frames (ORFs) predicted to encode a subgenomic protein 1 (sgP1) and a putative RNA-dependent RNA polymerase (RdRp). Multiple sequence alignment and phylogenetic analysis based on RdRp sequences from selected dsRNA viruses showed that CNRV1 shared 31.9% sequence identity with Nigrospora oryzae unassigned RNA virus 1 (NoNRV1) and clustered with NoNRV1 and four other mycoviruses. These viruses are unassigned and distant from members of the family Partitiviridae, although they were previously considered partitivirus-like viruses. Thus, CNRV1 is a novel member of proposed genus "Unirnavirus", and is the first dsRNA sequence reported from a member of the phylum Zoopagomycota. This study extends our knowledge about mycoviruses in basal fungi.

Conidiobolus pachyzygosporus invasive pulmonary infection in a patient with acute myeloid leukemia: case report and review of the literature.

BACKGROUND: Conidiobolus spp. (mainly C. coronatus) are the causal agents of rhino-facial conidiobolomycosis, a limited soft tissue infection, which is essentially observed in immunocompetent individuals from tropical areas. Rare cases of invasive conidiobolomycosis due to C. coronatus or other species (C.incongruus, C.lamprauges) have been reported in immunocompromised patients. We report here the first case of invasive pulmonary fungal infection due to Conidiobolus pachyzygosporus in a Swiss patient with onco-haematologic malignancy. CASE PRESENTATION: A 71 year-old female was admitted in a Swiss hospital for induction chemotherapy of acute myeloid leukemia. A chest CT performed during the neutropenic phase identified three well-circumscribed lung lesions consistent with invasive fungal infection, along with a positive 1,3-beta-d-glucan assay in serum. A transbronchial biopsy of the lung lesions revealed large occasionally septate hyphae. A Conidiobolus spp. was detected by direct 18S rDNA in the tissue biopsy and subsequently identified at species level as C. pachyzygosporus by 28S rDNA sequencing. The infection was cured after isavuconazole therapy, recovery of the immune system and surgical resection of lung lesions. CONCLUSIONS: This is the first description of C. pachyzygosporus as human pathogen and second case report of invasive conidiobolomycosis from a European country.

Genome-wide study of saprotrophy-related genes in the basal fungus Conidiobolus heterosporus.

Conidiobolus spp. are important saprophytic basal fungi. However, to date, no genomic-level data for decaying plant materials in the genus Conidiobolus has been reported. Here, we report that the 33.4-Mb genome of Conidiobolus heterosporus encodes 10,857 predicted genes. Conidiobolus heterosporus harbors 394 CAZyme-encoding genes belonging to 4 major modules but does not encode a polysaccharide lyase (PL). Many carbohydrate esterases (CEs) belonging to the family CE12 play crucial roles as pectin acetylesterases, and 14 genes were upregulated in the IM (fungus grown on inducing medium) among 17 expressed CE12 family genes. In addition, most of the genes in the GH132 CAZyme family showed a greater than 5-fold increase in expression in the IM compared with that in the wild type. Furthermore, 122 P450-encoding genes grouped into 11 families were detected in the fungal genome, most of which belonged to the CYP547 family (36 genes) followed by CYP548 (27 genes) and CYP5856 (25 genes). Interestingly, members of the families CYP5014 and CYP5136 were identified, the first time such enzymes have been described in a fungus. Our findings provide new insights into the genomics and genomic features of the saprophytic basal fungus C. heterosporus.Key Points• Genome of the saprobiotic basal fungus C. heterosporus was sequenced and analyzed.• 394 CAZymes but no PL family genes were found and expression levels were determined.• CE12 and GH132 proteins may play roles in the pectin and plant material degradation.• A large number of P450s but few P450 families existed in the fungus.

Characterization of a cytolytic-like gene from the aphid-obligate fungal pathogen Conidiobolus obscurus.

Cytolytic (Cyt)-like genes are known by omics analyses to exist widely in bacterial and fungal pathogens, but their insecticidal activities in fungi remains unknown. A full-length coding sequence of a Cyt-like gene was first amplified from Conidiobolus obscurus (an obligate aphid-pathogenic fungus) through RACE (rapid-amplification of cDNA ends). The deduced protein structure was structurally characterized by a single Cyt-typical α/ß domain. The expression level of the Cyt-like gene in conidia correlated well with the fungal virulence against aphids (r2 = 0.97). The results demonstrate the Cyt-like gene acts as an important virulence factor of C. obscurus against aphids, and has potential for exploitation in aphid control.

Mitochondrial genome of the entomophthoroid fungus Conidiobolus heterosporus provides insights into evolution of basal fungi.

Entomophthoroid fungi represent an ecologically important group of fungal pathogens on insects. Here, the whole mitogenome of Conidiobolus heterosporus, one of the entomophthoroid fungi, was described and compared to those early branching fungi with available mitogenomes. The 53,364-bp circular mitogenome of C. heterosporus contained two rRNA genes, 14 standard protein-coding genes, 26 tRNA genes, and three free-standing ORFs. Thirty introns interrupted nine mitochondrial genes. Phylogenetic analysis based on mitochondrion-encoded proteins revealed that C. heterosporus was most close to Zancudomyces culisetae in the Zoopagomycota of basal fungi. Comparison on mitogenomes of 23 basal fungi revealed great variabilities in terms of mitogenome conformation (circular or linear), genetic code (codes 1, 4, or 16), AT contents (53.3-85.5%), etc. These mitogenomes varied from 12.0 to 97.3 kb in sizes, mainly due to different numbers of genes and introns. They showed frequent DNA rearrangement events and a high variability of gene order, although high synteny and conserved gene order were also present between closely related species. By reporting the first mitogenome in Entomophthoromycotina and the second in Zoopagomycota, this study greatly enhanced our understanding on evolution of basal fungi.

Successful Treatment of Invasive Conidiobolus Infection During Therapy for Acute Lymphoblastic Leukemia.

Invasive fungal infections are a serious cause of morbidity and mortality in patients with hematologic malignancies. Conidiobolus species are molds within the order Entomophthorales and may disseminate to become rapidly fatal in immunocompromised individuals. This species of fungal infections are often multidrug resistant (MDR) and present unique therapeutic challenges. Reports of Conidiobolus infections are rare in pediatric oncology. We report the successful treatment of an adolescent male with B-cell lymphoblastic leukemia and MDR invasive sinopulmonary Conidiobolus infection with emphasis on early and aggressive neutrophil support with surgical debridement. The strategies described could be applied to other MDR fungal infections.

Blooming of Unusual Cytochrome P450s by Tandem Duplication in the Pathogenic Fungus Conidiobolus coronatus.

While the Zygomycete fungus Conidiobolus coronatus primarily infects insects, it can be pathogenic to mammals as well, including humans. High variability in the treatment of this fungal infection with currently available drugs, including azole drugs is a very common phenomenon. Azoles bind to the cytochrome P450 monooxygenases (P450s/CYP) including CYP51, a sterol 14-α-demethylase, inhibiting the synthesis of cell membrane ergosterol and thus leading to the elimination of infecting fungi. Despite P450's role as a drug target, to date, no information on C. coronatus P450s has been reported. Genome-wide data mining has revealed the presence of 142 P450s grouped into 12 families and 21 subfamilies in C. coronatus. Except for CYP51, the remaining 11 P450 families are new (CYP5854-CYP5864). Despite having a large number of P450s among entomopathogenic fungi, C. coronatus has the lowest number of P450 families, which suggests blooming P450s. Further analysis has revealed that 79% of the same family P450s is tandemly positioned, suggesting that P450 tandem duplication led to the blooming of P450s. The results of this study; i.e., unravelling the C. coronatus P450 content, will certainly help in designing experiments to understand P450s' role in C. coronatus physiology, including a highly variable response to azole drugs with respect to P450s.

Experimental infection in gerbils by Conidiobolus lamprauges.

Conidiobolomycosis is an emerging entomophthoramycosis caused by fungi Conidiobolus spp. Animal models are essential for the study of infectious disease in various areas such as pathogenesis, diagnostic methods, treatment and prevention. There is not currently an animal model for conidiobolomycosis. The aim of this study was to create an experimental infection protocol for Conidiobolus lamprauges in gerbils (Meriones unguiculatus). The study animals were randomly divided into four groups of four animals: immunosuppressed with cyclophosphamide (CPA) and infected with C. lamprauges (G1), immunocompetent and infected with C. lamprauges (G2), immunosuppressed with CPA (G3), and an immunocompetent control group (G4). Clinical signs were observed only in G1 animals, where the mortality rate reached 75% by day 7 after infection (AI) with a median survival of 2 days. C. lamprauges was detected only in G1, both by PCR and by isolation. Necropsies of the G1 animals showed lesions in the nasal cavity and lung tissue. These lesions were characterized by polymorphonuclear infiltrate cells and by the presence of hyphal structures under silver staining. This animal model will be useful for further investigation of diseases caused by C. lamprauges, particularly of those associated with immunosuppression factors in naturally occurring animal infections.

Cuticle hydrolysis in four medically important fly species by enzymes of the entomopathogenic fungus Conidiobolus coronatus.

Entomopathogenic fungi infect insects via penetration through the cuticle, which varies remarkably in chemical composition across species and life stages. Fungal infection involves the production of enzymes that hydrolyse cuticular proteins, chitin and lipids. Host specificity is associated with fungus-cuticle interactions related to substrate utilization and resistance to host-specific inhibitors. The soil fungus Conidiobolus coronatus (Constantin) (Entomophthorales: Ancylistaceae) shows virulence against susceptible species. The larvae and pupae of Calliphora vicina (Robineau-Desvoidy) (Diptera: Calliphoridae), Calliphora vomitoria (Linnaeus), Lucilia sericata (Meigen) (Diptera: Calliphoridae) and Musca domestica (Linnaeus) (Diptera: Muscidae) are resistant, but adults exposed to C. coronatus quickly perish. Fungus was cultivated for 3 weeks in a minimal medium. Cell-free filtrate, for which activity of elastase, N-acetylglucosaminidase, chitobiosidase and lipase was determined, was used for in vitro hydrolysis of the cuticle from larvae, puparia and adults. Amounts of amino acids, N-glucosamine and fatty acids released were measured after 8 h of incubation. The effectiveness of fungal enzymes was correlated with concentrations of compounds detected in the cuticles of tested insects. Positive correlations suggest compounds used by the fungus as nutrients, whereas negative correlations may indicate compounds responsible for insect resistance. Adult deaths result from the ingestion of conidia or fungal excretions.

Pathogenicity of Conidiobolus coronatus and Fusarium solani in mouse models.

To study the pathogenicity of Conidiobolus coronatus (C. coronatus) and Fusarium solani (F. solani) in animal models. Immunocompromised mice were treated with cyclophosphamide and prednisolone via intraperitoneal injection before and after inoculation. According to pathogenic characteristics of different fungi, C. coronatus was used to infect mice via intravenous inoculation, intraperitoneal inoculation, gastrointestinal infusion and intradermal inoculation methods. And F. solani was used to infect mice by inoculation via the abraded or normal skin. In the group of immunocompromised mice, C. coronatus was isolated from the lung tissues of one mouse on day 7 and another on day 10 respectively. The corresponding histopathology revealed infiltration of local inflammatory cells in the lung tissue. Pathogenic lesions were observed in all normal and immunocompromised mice infected with F. solani via abraded skin. The lesions in the immunocompromised mice were more severe and persisted longer than those in the normal mice. Moreover, hyphae were mostly observed in the histopathological examination and fungal culture from the immunocompromised mouse. The pathogenicity of C. coronatus was relatively weak as it did not induce local infections and did not disseminate the disease in immunocompetent and immunocompromised mice. Therefore, F. solani is a type of opportunistic pathogenic fungus, and abraded skin is one of the causative routes of infection.

Coronatin-2 from the entomopathogenic fungus Conidiobolus coronatus kills Galleria mellonella larvae and incapacitates hemocytes.

Coronatin-2, a 14.5 kDa protein, was isolated from culture filtrates of the entomopathogenic fungus Conidiobolus coronatus (Costantin) Batko (Entomophthoramycota: Entomophthorales). After LC-MS/MS (liquid chromatography tandem mass spectrometry) analysis of the tryptic peptide digest of coronatin-2 and a mass spectra database search no orthologs of this protein could be found in fungi. The highest homology was observed to the partial translation elongation factor 1a from Sphaerosporium equinum (protein sequence coverage, 21%), with only one peptide sequence, suggesting that coronatin-2 is a novel fungal protein that has not yet been described. In contrast to coronatin-1, an insecticidal 36 kDa protein, which shows both elastolytic and chitinolytic activity, coronatin-2 showed no enzymatic activity. Addition of coronatin-2 into cultures of hemocytes taken from larvae of Galleria mellonella Linnaeus (Lepidoptera: Pyralidae), resulted in progressive disintegration of nets formed by granulocytes and plasmatocytes due to rapid degranulation of granulocytes, extensive vacuolization of plasmatocytes accompanied by cytoplasm expulsion, and cell disintegration. Spherulocytes remained intact, while oenocytes rapidly disintegrated. Coronatin-2 produced 80% mortality when injected into G. mellonella at 5 µg larva-1. Further study is warranted to determine the relevance of the acute toxicity of coronatin-2 and its effects on hemocytes in vitro to virulence of C. coronatus against its hosts.

Conidiobolus macrosporus (Entomophthorales), a mosquito pathogen in Central Brazil.

A new fungal pathogen of Culicinae (Diptera: Culicidae) adults, Conidiobolus macrosporus (Entomophthorales: Ancylistaceae), was detected and isolated during a survey of mosquito pathogens close to the city of Aruanã, Goiás State, in December 2014. The morphological characteristics of C. macrosporus are presented, and reasons for some uncertainty about this identification are discussed. The pathogenicity and high virulence of this fungus for Aedes aegypti were confirmed in laboratory conditions. Mortality of adults exposed to conidia was observed within 24h of exposure to the pathogen, and increased to 100% as quickly as 3days after inoculation (with the highest conidial concentration tested, 8.3×10(4)conidia/cm(2)). Repeated attempts to obtain genomic sequence data failed despite confirmations that the DNA extraction methods were themselves successful.