Oil-in-water Pickering emulsions stabilized by titania (TiO2) nanoparticles have shown potential to increase ultraviolet (UV) protection in the entomopathogenic fungus Metarhizium brunneum. In this study, we expand the findings by comparing several nanoparticle-based formulations for UV tolerance, and investigating the impact of protective formulations in a biocontrol setting. The fungal viability in colony forming units (CFUs) and virulence to the 2nd instar tobacco thrips, Frankliniella fusca, were assessed. Under UV-A (380-nm), a titania-based formulation was effective in protecting the fungal viability at 6-h exposure but not at 12-h; silica (SiO2) did not provide any UV protection. UV-A radiation for up to 12 h did not reduce the fungal virulence in any treatment; then a stronger UV treatment was warranted. Under UV-C (254-nm), silica was ineffective in improving the viability or virulence of M. brunneum. The titania-based emulsion showed partial protection for up to 10-min exposure, with 51-56% reduction in CFU counts compared to nearly 100% reduction in the control, while it only exhibited marginal effect in assessing fungal virulence. Two titania-based formulations (titania-MO-1 and titania-PO-2) were further explored for enhanced UV tolerance. Titania-MO-1 had fewer CFUs at 10-min UV compared to control; titania-PO-2 showed no reduction in fungal viability. The two titania formulations were equally effective in maintaining fungal virulence to F. fusca regardless of UV exposure. Overall, titania nanoparticles (particularly titania-PO-2) protected M. brunneum conidia against UV radiation, suggesting the potential use of titania nanoparticles in formulating M. brunneum for improved UV tolerance and biocontrol potential.
Although Akanthomyces attenuatus JEF-147 exhibits high virulence against the two-spotted spider mite (Tetranychus urticae), its molecular mechanisms remain poorly understood. This study investigated fungal gene expression during early pathogenesis to elucidate how JEF-147 overcomes host defenses. Treatment on adults significantly suppressed descendant nymph populations. RNA-sequencing revealed time-dependent transcriptomic shifts: at 36-h after treatment, DEGs were primarily associated with transcription and translation, whereas 72-h samples showed activation of genes related to pathogenesis and stress management. Pathway analysis indicated that 72-h DEGs were enriched in metabolic pathways, suggesting JEF-147 maximizes energy production (TCA cycle and oxidative phosphorylation) and reinforces cell walls (glucan biosynthesis). The fungus actively utilizes host-derived fatty acids and proteins while maintaining homeostasis via the glutathione pathway. Furthermore, enrichment in vacuolar degradation pathways including autophagy and endocytosis in 72-h samples suggests active digestion of host nutrients. It was partially supported via LC-MS/MS analysis of fungal supernatants from a saprophytic culture. Our results suggest a two-stage infection strategy: an initial 36-h phase focused on hyphal growth and penetration, followed by a 72-h transition to counteracting host defenses through up-regulation of virulence and stress management-related genes. This work provides critical insights into the infection mechanisms of mite-pathogenic fungi.
Honey bee colonies are threatened by several pathogens, including Paenibacillus larvae, Melissococcus plutonius, Vairimorpha apis, and Vairimorpha ceranae. Those infections affect bee health, survival, and productivity. The social behavior of the bees facilitates the spread of these pathogens, making disease management a significant challenge in apiculture. This study aimed to assess the historical presence of Paenibacillus larvae, Melissococcus plutonius, Vairimorpha apis, and Vairimorpha ceranae in honey samples from Rio Grande do Sul, Brazil. A total of 125 archival honey samples collected from 2011 to 2022 were retrospectively evaluated. The samples had previously been analyzed for physicochemical and botanical origins. DNA was extracted from honey and spores, followed by PCR assays targeting the four pathogens. Sequencing was performed to confirm the results. M. plutonius was the most frequently detected pathogen, identified in 112 samples (89.6%), followed by V. ceranae, which was present in 67 samples (53.6%). In contrast, P. larvae were identified in only six samples (8.8%), and V. apis was absent. The high detection rate of M. plutonius suggests its widespread distribution in South Brazilian apiaries. The absence of V. apis suggests that V. ceranae has displaced this specie in the region. The presence of P. larvae spores emphasizes its resilience through the ability to persist for extended periods in the environment. Additionally, the simultaneous detection of multiple pathogens raises the concern for synergic effects or interactions, which could further increase colony losses. Finally, these findings highlight the importance of continuous surveillance and enhanced biosecurity and prophylactic strategies, altogether essential for honey bee health and productivity.
Numerous studies have reported the occurrence of mycoviruses in fungal strains of medical-veterinary, phytopathological, and entomological relevance, with an expanding literature on their phenotypic effects. However, their prevalence within fungal populations remains poorly understood. If mycoviral infections were to confer adaptive advantages to their fungal hosts, positive selection could favour their persistence within fungal populations, potentially leading to an increased prevalence of beneficial viral symbionts. Addressing this gap is essential for improving mycovirus-based biocontrol strategies. Here, using a collection of 11 B. bassiana strains, we investigated whether mycovirus prevalence is associated with increased virulence. Six out of the 11 strains harbored single or mixed mycovirus infections, including Beauveria bassiana victorivirus 1 (BbVV-1), partitivirus 2 (BbPV-2), and polymycovirus 1 (BbPmV-1). In these mycovirus-harbouring strains, mycovirus-free (MFr) isogenic lines were generated from the wild mycovirus-infected (WMI) strains, and virulence against Galleria mellonella larvae was compared. In general, mycovirus presence was associated with increased virulence. To quantify mycovirus prevalence within clonal populations, 480 clones (80 per strain) were analysed by qRT-PCR. Clonal analyses revealed marked strain-dependent variation, ranging from 10.0% to 92.5% prevalence. Importantly, regression analysis demonstrated a strong positive relationship between mycovirus prevalence and the increase in mortality observed in WMI relative to MFr isogenic lines (R2 = 0.879), indicating an approximately proportional association. Collectively, these findings provide the first evidence that mycovirus prevalence within B. bassiana populations can confer a selective advantage through increased virulence highlighting the importance of population-level characterization for the selection and preservation of fungal biocontrol agents.
The ectoparasitoid wasp, Habrobracon hebetor, targets a range of Lepidopteran larvae and plays an important role in biological control efforts of insect pests. The venom of H. hebetor contains a variety of components with paralytic, neurotoxic and immune-modulatory properties. Herein, we explored the interactions between the entomopathogenic fungus (EPF) Metarhizium robertsii and the integument/cuticle defence reactions of wax moth larvae, Galleria mellonella, (Lepidoptera: Pyralidae) post-envenomation by H. hebetor to gain much needed insight into the mechanisms of disease susceptibility. Envenomation of G. mellonella led to a dramatic decrease in phenoloxidase (PO) enzyme activity and the transcription of proPhenoloxidase (proPO) cascade genes in the integument. Concurrently, M. robertsii expressed several virulence factors that were more active on the cuticle of immobilized (envenomed) insects compared to control insects. Interestingly, G. mellonella larvae envenomed by the parasitoid, and infected with the fungus, could still maintain high levels of antimicrobial gene expression in the cuticle. We present data on the complex interplay between an insect host, an entomopathogenic fungus, and the venom of an ectoparasitoid wasp.
Parasitic castration represents a strategy by which parasites suppress host reproduction by consuming gonads, disrupting the endocrine system, or indirectly manipulating host resource allocation. The nematode Bradynema listronoti Zeng parasitizes both sexes of the carrot weevil, Listronotus oregonensis (LeConte), but induces castration only in females. This study investigates the physiological and morphological impacts of B. listronoti parasitism on host developmental time, size, lipid metabolism, and supercooling point (SCP). It was hypothesized that castration would induce gigantism or enhance freeze tolerance in host females through reproductive resource reallocation, but not in males whose reproduction is unaffected by parasitism. Parasitism significantly prolonged host developmental time by 7% in both sexes, but it did not affect body weight in either males or females. Lipid analysis revealed that parasitized individuals had significantly lower total lipid reserves (-30%) and contained novel eicosanoids, suggesting shifts in lipid metabolism or incorporation of nematode-derived fatty acids. SCP were largely unaffected by parasitism, except in spring-collected weevils, where parasitism reduced SCP by ∼19%. Sex effects were only detected in late-summer weevils, when males exhibited ∼15% higher SCP than females. These results indicate that B. listronoti imposes physiological costs on its host, affecting development and lipid metabolism similarly in males and females, with limited context-dependent effects on cold tolerance. Overall, these findings highlight the complex effects of parasitic castration and their potential implications for host population dynamics and biological control strategies.
Bombyx mori lipase-1 (Bmlipase-1) has strong anti-BmNPV activity, but the mechanism by which Bmlipase-1 resists BmNPV invasion has not been elucidated so far. In this paper, based on the construction of recombinant viruses overexpressing Bmlipase-1, we analyzed the effects of the recombinant viruses on the genes related to recombinant virus replication as well as viral replication and proliferation after the recombinant viruses infected BmN cells. In the presence of the virus, Bmlipase-1 localizes to the cell nucleus. Quantitative polymerase chain reaction (qPCR), northern blotting and western blot analyses showed that Bmlipase-1 inhibited the expression of BmNPV DNA-binding protein (dbp) as well as the replication and proliferation of the recombinant virus. DBP is a key factor for normal viral DNA replication and for the stabilization of nascent viral DNA. A biotin-labeled probe was synthesized around the c-Myb transcription factor binding site in the upstream promoter region of dbp and analyzed by EMSA with prokaryotically expressed and purified Bmlipase-1. It was found that Bmlipase-1 could bind to CACTTCAATT in the dbp promoter region, while the activity of the dbp promoter lacking CACTTCAATT was significantly reduced. In conclusion, Bmlipase-1 can bind to the CACTTCAATT motif on the dbp promoter in vitro, and this motif contributes positively to the activity of the dbp promoter. Overexpression of Bmlipase-1 significantly downregulates dbp expression and inhibits viral replication. Based on these findings, we propose the following hypothesis: Bmlipase-1 may inhibit viral replication by binding to the CACTTCAATT motif and interfering with the transcriptional regulation of dbp. However, this regulatory model requires further validation in the context of viral infection. This paper provides a new theoretical basis for the prevention and control of lepidopteran insect viruses, and also opens up a new way to study the antiviral mechanism of the silkworm, Bombyx mori.
The tricarboxylic acid (TCA) cycle plays a pivotal role in fungal physiological processes. In this study, two TCA-cycle related enzyme were functionally analyzed in a model entomopathogenic fungus Beauveria bassiana, including NAD-dependent lactate dehydrogenase (BbLdh) and malate dehydrogenase (BbMdh1 and 2). Domain annotation indicated all these enzymes contained an Ldh_1 domain. Functional analyses indicated that BbLdh and BbMdh2 had differential contributions to fungal growth, development, stress tolerance, virulence, and mycosis. Notably, BbLdh played a more important role in fungal interaction with the host than BbMdh2, which was attributed to its additional functions in stress tolerance, extracellular acidification, in vivo development, and immune evasion. In contrast, BbMdh2 primarily was involved in cuticle penetration due to its roles in utilization of host nutrients (e.g., lipids and proteins). Comparative transcriptomic analysis revealed that BbLdh mediated numerous metabolic pathways and physiological responses to oxidative stress. Collectively, this study reveals the metabolic mechanisms involved in the B. bassiana adaptation to the host niches, deepening our understanding of metabolic pathways during fungal interaction with the hosts.
Invertebrate Iridescent Virus 31 (IIV-31, or Iridovirus armadillidium1) is a large double-stranded DNA virus that induces iridescence and high mortality in terrestrial isopods. Despite its broad distribution, its pathogenic mechanisms and interactions with host immunity and endosymbionts are poorly understood. We examined the effects of IIV-31 infection on survival, hemocyte concentration and viability, septicemia, and viral load in Armadillidium vulgare, while testing for protective effects of the feminizing endosymbiont Wolbachia (wVulC strain). Virgin adults from asymbiotic (males and females) and Wolbachia-symbiotic (females only) lineages were experimentally infected by needle pricking. Infected individuals exhibited typical iridescence from ∼6 days post-infection (dpi), culminating in 100% mortality after 80 days. Wolbachia conferred no significant survival benefit (log-rank test, p = 0.42). However, despite attaining 100% mortality in both sexes by 80 dpi, females exhibited delayed mortality kinetics compared to males (Cox proportional hazards model, p = 0.04). Infected isopods displayed a marked reduction of circulating hemocyte numbers (negative binomial GLMM, p < 0.0001) and elevated septicemia (p = 0.008), with higher septicemia in infected females relative to their controls, but no sex difference in viral load at 30 dpi (p = 0.23). These findings demonstrate that IIV-31 causes reduction of circulating hemocyte counts and opportunistic septicemia, with female-specific tolerance but no Wolbachia-mediated protection, underscoring sexual dimorphism in immune responses as a pivotal factor in isopod-iridovirus dynamics.
The brown planthopper, Nilaparvata lugens, is a major rice pest causing significant yield losses across Asia. Concerns over the environmental, health, and resistance-related impacts of current chemical control strategies highlight the need for sustainable alternatives. In this study, we isolated and characterized a novel entomopathogenic fungus, strain NLS-1, from mycosed N. lugens cadavers. Based on morphological observations and internal transcribed spacer (ITS) sequence analysis, strain NLS-1 was assigned to Aspergillus section Flavi and designated as Aspergillus sp. NLS-1. Bioassays revealed that the isolate exhibited high virulence against third-instar N. lugens nymphs; the highest concentration of 1 × 108 conidia/mL resulted in 97.22% corrected mortality by 9 days post-inoculation and a median lethal time (LT50) of 4.13 days. Scanning electron microscopy delineated the infection process, confirming firm conidial adhesion to the cuticle, followed by germination, hyphal proliferation, and eventual host colonization. Furthermore, fungal infection significantly altered the nymphs' bacterial community structure, notably affecting the relative abundances of Acinetobacter and Serratia. These findings position Aspergillus sp. NLS-1 as a promising biocontrol agent and suggest that its pathogenicity may be mediated through the disruption of the host's microbiota, providing new insights for the integrated management of N. lugens.
Honey bee colonies can be infested by a range of pathogens, resulting in considerable morbidity and mortality. Detection and identification of pathogens in bee colonies is thus essential in apiculture, and various matrices are used for screening for pathogens within a colony, including hive debris, bees, and the combs. Previous investigations have explored using honey as a non-invasive sample material for detection of pathogen DNA, but have rarely compared the results with those from molecular analysis from other matrices. In this study, samples of bees, honey, and hive debris from beekeepers in Norway were investigated for several pathogens: Acarapis woodi, Crithidia mellificae, Lotmaria passim, Ascosphaera apis, Nosema apis and Nosema ceranae. For all sample types and all pathogens, pathogen-specific qPCR was used for detection, with microscopy methods also used for A. woodi and Nosema spp. Honey was the most difficult matrix to work with in the laboratory, and detection seemed to be lower than in hive debris or bees, depending on pathogen. While hive debris seems to be the optimal matrix for investigating honey bee colonies for Nosema spp. and A. apis, for L. passim bee samples provided the most positive results, and with lower Cq values. qPCR was significantly more sensitive for detecting Nosema than microscopy, and also provides the species information. None of our samples were positive for A. woodi or C. mellificae, but A. apis and Nosema spp. occur widely among apiaries in southern Norway, with N. apis being the predominant Nosema species.
Bombyx mori nucleopolyhedrovirus (BmNPV) is a major viral pathogen of silkworms, causing significant economic losses in the sericulture industry. BmNPV infection can induce host-cell apoptosis as an antiviral defense response, whereas the virus must suppress premature apoptosis to complete productive infection. However, the underlying mechanisms remain to be elucidated. Currently, no effective control strategies are available for managing BmNPV infection in silkworms. We previously observed a significant increase in BmJun protein levels after BmNPV infection. Members of the Jun protein family serve as important substrates in the JNK/MAPK signaling pathway and are vital for cellular responses to viral infections and apoptosis. Nevertheless, its function in B. mori has yet to be fully elucidated. Here, we showed that overexpression of BmJun significantly enhanced BmNPV proliferation. Subsequently, chromatin immunoprecipitation sequencing (ChIP-seq) revealed significant enrichment of BmJun at the promoter of the viral anti-apoptotic gene p35, and this association was further confirmed by ChIP-qPCR. Dual-luciferase reporter assays showed that BmJun activates p35 transcription through the -255 to -75 bp region of the p35 promoter. BmJun overexpression reduced host-cell apoptosis, consistent with its activation of the viral anti-apoptotic gene p35, thereby contributing to BmNPV proliferation. These findings suggest that BmJun may facilitate BmNPV proliferation by transcriptionally activating p35 and suppressing host-cell apoptosis. Together, these findings provide new insight into the molecular interactions between B. mori and BmNPV and advance our understanding of baculovirus pathogenesis.
Newly mated queens and nest-collected reproductive males of Solenopsis invicta were surveyed for the presence of all RNA viruses known or described from this ant. Six RNA viruses were detected in monogyne newly mated queens, including Solenopsis invicta virus 1 (SINV1), SINV3, SINV4, SINV6, SINV7, and SINV14. These and an additional virus, SINV9, were detected in polygyne queens. Five RNA viruses were detected in male alates, including SINV1, SINV4, SINV6, SINV7, and SINV14. Queens may be one source responsible for virus dissemination during founding.
Burn spot disease, a form of shell disease in crayfish, has been linked to Fusarium avenaceum (in Astacus astacus and Pontastacus leptodactylus from Estonia and Turkey) and Fusarium solani (in a distinct form on Saaremaa Island, Estonia). Severe melanised lesions in P. leptodactylus from Belarus's Lyubanskoye Reservoir resemble the Saaremaa syndrome. This study aimed to characterise the culturable microorganisms in these lesions and to test for Fusarium species. We performed the first culture-based molecular characterisation of lesion-associated fungi and oomycetes in this host, using ITS rDNA sequencing, phylogenetic analysis, Fusarium-specific PCR and genotype-specific real-time PCR. From 15 severely affected individuals, 19 isolates were obtained: 14 oomycetes and five fungi. Oomycetes included Aphanomyces astaci, Saprolegnia parasitica, Saprolegnia australis, two unidentified Saprolegniaceae lineages, Pythium flevoense, and unidentified Pythium spp. Fungi comprised Epicoccum nigrum, Plectosphaerella sp., Penicillium sp., Cladosporium sp., and Catenaria sp., the last being a first record from crayfish. The A. astaci isolate belonged to genotype group B. No Fusarium isolates were recovered in culture, and no Fusarium DNA was detected by universal ITS, genus-level nested TEF1 or species-specific assays applied to lesion-derived DNA. Severe melanised lesions in this population harbour a taxonomically diverse, oomycete-dominated microbial assemblage. Because non-lesioned control tissue, histopathology and experimental infections were not included, the recovered taxa are reported as lesion-associated organisms, and their individual and combined roles in lesion initiation and progression remain to be tested.
Ecytonucleospora hepatopenaei (EHP), the causative agent of shrimp hepatopancreatic microsporidiosis (HPM), induces growth retardation, heightened secondary infection susceptibility, and substantial global shrimp aquaculture economic losses. The lack of mechanistic insights into EHP pathogenesis, particularly key virulence factors, has impeded diagnostics and therapeutics development. Here, a novel EHP spore wall protein, EhSWP8, was characterized by bioinformatics profiling, prokaryotic expression/antibody production, indirect immunofluorescence assay (IFA), and immunoelectron microscopy (IEM). EhSWP8 (326 aa, 36.8 kDa) contained 34 predicted phosphorylation sites, two N-glycosylation sites, and a heparin-binding motif (HBM, residues 50-55, YKKMKQ) characterized by an overall positively charged surface and high relative solvent accessibility (RSA > 0.5), suggesting that the motif is surface-exposed and structurally competent to mediate molecular interactions. EhSWP8 shared the closest phylogenetic affinity with Enterocytozoon bieneusi hypothetical protein EDQ31248.1, and its identity was 100% across five geographic EHP strains. Recombinant EhSWP8 expressed in Escherichia coli Rosetta was confirmed by SDS-PAGE. Western blot verified the polyclonal antibody specifically against native EhSWP8 in purified EHP spores. IFA/IEM revealed predominant exospore localization of EhSWP8. Re-analysis of three public omics datasets further showed that EhSWP8 is the fifth most abundant EHP transcript during host infection (median ranks #4-#8 of 2536 transcripts), that the EhSWP8 protein increases 41.6-fold with infection burden. Crucially, a heparin magnetic-bead assay provided functional evidence that native, surface-exposed EhSWP8 mediates heparin-dependent adhesion of EHP spores, with free-heparin competition and antibody blocking reducing binding by 70.6% and 39.4%, respectively. These findings establish EhSWP8 as a conserved, heparin-dependent adhesin, positioning it as both a novel surveillance target and a foundation for mechanistic insights into EHP pathogenesis.
The Asian citrus psyllid, Diaphorina citri, is the primary vector of Candidatus Liberibacter asiaticus, the causative agent of citrus greening disease, which continues to threaten citrus production worldwide. Current management relies heavily on chemical insecticides, despite increasing concerns regarding resistance and environmental impacts. Because pathogen acquisition is most efficient during the nymphal stage, management strategies targeting immature psyllids may improve disease suppression. Although bacterial pesticidal proteins (BPP) have generally shown limited activity against D. citri, previous studies have focused on adults or late instar nymphs, potentially underestimating the susceptibility of earlier developmental stages. To address this gap, we conducted the largest screen to date of BPP against first instar D. citri. Thirteen proteins representing multiple structural classes were expressed in Bacillus thuringiensis or Escherichia coli, purified, and evaluated using sandwich feeding bioassays. Toxicity was assessed against first instar nymphs at a single dose, and LC50 values determined for proteins including Tpp78Aa1, Tpp78Ba1, Cry1Ca, Cry1Ea, that caused significant mortality relative to controls in the single-dose assays. Tpp78Aa1 and Cry1Ca were the most toxic, with LC50 values of 10.4 and 6.7 μg/mL, respectively. Marked disruption of the gut brush border and severe loss of microvilli was observed by transmission electron microscopy in fourth instar nymphs fed on Tpp78Aa1. These findings demonstrate the toxicity of Tpp78Ba1, Cry1Ca and Cry1Ea to D. citri for the first time and highlight the increased susceptibility of first instar nymphs to BPP relative to later developmental stages, supporting the targeting of this development stage in psyllid management programs.
Six subclass III C6 transcription factors (TFs) with unique Zn(II)2Cys6 binuclear cluster DNA-binding (C6 or GAL4) domain not locating at N-terminus are underexplored in Beauveria bassiana, a wide-spectrum mycoinsecticide. Here, we report that three C6 TFs with the GAL4 domain locating at C-terminus (TF1), between C-terminal and central regions (TF2) and between central and N-terminal regions (TF3) are largely differentiated in function. TF1 was proven to localize in both nucleus and cytoplasm and regulate host immune repression in the course of host hemocoel colonization instead of cuticular penetration. The deletion of tf1 resulted in much greater virulence loss via normal cuticle infection (77%) than cuticle-bypassing infection (25%) for direct hemocoel colonization by intrahemocoel injection. The deletion also led to severe defects in radial growth, multiple stress tolerances, aerial conidiation, and submerged blastospore production as well as resistance to host immune defense after invasion into host hemocoel, unveiling pleiotropic effects of TF1 in the fungal lifecycle. TF3 was similar to TF1 in subcellular feature and exhibited lesser role than TF1 in mediating conidiation and blastospore production but no other role. TF2 looks like a typical subclass III C6 TF but proved functionally null perhaps due to its localization in neither nucleus nor cytoplasm under normal culture conditions. These findings add knowledge to subclass III C6 TFs and unveil a significance of host immune suppression for the insecticidal activity of B. bassiana after hyphal invasion into insect hemocoel through cuticular penetration.
The surfaces of microsporidian spores are frequently adorned with filamentous appendages of unknown origin and function. Although some studies suggest that these structures may be host-acquired, the absence of identified parasite-encoded components has hindered our understanding of their biogenesis and role in infection. Here, we applied surface shaving proteomics to profile the surface-exposed proteins of Ameson portunus -a microsporidian pathogen causing severe myopathy in portunid crabs. Our analysis identified 120 candidate surface proteins. Nineteen of these were highly enriched by both direct shaving and SDS-assisted methods, representing a high-confidence surfome. Among these, a previously uncharacterized protein, designated 8-2.11, was confirmed via immunofluorescence assay and immunoelectron microscopy. It was expressed early in development stage and specifically localized to the spore wall and hair-like projections (HLPs) of microsporidia. Notably, polyclonal antibodies against recombinant 8-2.11 recognized a native protein in spores, specifically labeled the HLP structures, and showed no cross-reactivity with host cells. Our results provide the first evidence of a parasite-encoded protein that is integral to HLP formation, challenging the prevailing hypothesis that these surface filaments are solely host-derived. This study establishes surface shaving as a powerful tool for microsporidian research and highlights 8-2.11 as a promising candidate for future functional studies on spore surface biology and host-parasite interactions.
Long noncoding RNAs (lncRNAs) have been demonstrated to participate in apoptosis and host-virus interactions. Apoptosis is a host mechanism for defending against virus invasion. Bombyx mori nucleopolyhedrovirus (BmNPV) is one of the primary pathogens infecting the silkworm. However, little is known concerning whether the silkworm body activates apoptotic programs against BmNPV infection via lncRNAs. This study aimed to identify apoptosis-related lncRNAs involved in BmNPV infection in silkworms. Through transcriptome sequencing, the study identified a lncRNA co-expressed with BmIAP (Bombyx mori Inhibitor of Apoptosis Protein) named Lnc Unc-89-AS1. Fluorescence in situ hybridization (FISH) experiments indicated that Lnc Unc-89-AS1 was localized to both the nucleus and cytoplasm of BmE-SWU1 cells. We further investigated the regulatory role of Lnc Unc-89-AS1 in modulating apoptosis and BmNPV infection. Caspase activity assays, flow cytometry, qRT-PCR and mitochondrial membrane potential analysis demonstrated its function in inhibiting apoptosis in silkworm cells by participating in the mitochondrial apoptosis pathway. Overexpression and interference with Lnc Unc-89-AS1 in silkworm cells confirmed that it contributes to BmNPV proliferation at both the transcriptional and translational levels. These findings reveal a novel mechanism by which Lnc Unc-89-AS1 influences BmNPV infection by regulating apoptosis, providing new insights into host antiviral defenses relevant to the prevention and control of silkworm diseases.
