Viral Pathogens Research Articles

Eilat virus (EILV) causes superinfection exclusion against West Nile virus (WNV) in a strain-specific manner in Culex tarsalis mosquitoes.

West Nile virus (WNV) is the leading cause of mosquito-borne illness in the USA. There are currently no human vaccines or therapies available for WNV, and vector control is the primary strategy used to control WNV transmission. The WNV vector Culex tarsalis is also a competent host for the insect-specific virus (ISV) Eilat virus (EILV). ISVs such as EILV can interact with and cause superinfection exclusion (SIE) against human pathogenic viruses in their shared mosquito host, altering vector competence for these pathogenic viruses. The ability to cause SIE and their host restriction make ISVs a potentially safe tool to target mosquito-borne pathogenic viruses. In the present study, we tested whether EILV causes SIE against WNV in mosquito C6/36 cells and C. tarsalis mosquitoes. The titres of both WNV strains - WN02-1956 and NY99 - were suppressed by EILV in C6/36 cells as early as 48-72 h post-superinfection at both m.o.i. values tested in our study. The titres of WN02-1956 at both m.o.i. values remained suppressed in C6/36 cells, whereas those of NY99 showed some recovery towards the final timepoint. The mechanism of SIE remains unknown, but EILV was found to interfere with NY99 attachment in C6/36 cells, potentially contributing to the suppression of NY99 titres. However, EILV had no effect on the attachment of WN02-1956 or internalization of either WNV strain under superinfection conditions. In C. tarsalis, EILV did not affect the infection rate of either WNV strain at either timepoint. However, in mosquitoes, EILV enhanced NY99 infection titres at 3 days post-superinfection, but this effect disappeared at 7 days post-superinfection. In contrast, WN02-1956 infection titres were suppressed by EILV at 7 days post-superinfection. The dissemination and transmission of both WNV strains were not affected by superinfection with EILV at either timepoint. Overall, EILV caused SIE against both WNV strains in C6/36 cells; however, in C. tarsalis, SIE caused by EILV was strain specific potentially owing to differences in the rate of depletion of shared resources by the individual WNV strains.

Identification and characterization of the siderochelin biosynthetic gene cluster via coculture.

Many microbial biosynthetic gene clusters (BGCs) are inactive under standard laboratory conditions, making characterization of their products difficult. Silent BGCs are likely activated by specific cues in their natural environment, such as the presence of competitors. Growth conditions such as coculture with other microbes, which more closely mimic natural environments, are practical strategies for inducing silent BGCs. Here, we utilize coculture to activate BGCs in nine actinobacteria strains. We observed increased production of the ferrous siderophores siderochelin A and B during coculture of Amycolatopsis strain WAC04611 and Tsukamurella strain WAC06889b. Furthermore, we identified the siderochelin BGC in WAC04611 and discovered that the GntR-family transcription factor sidR3 represses siderochelin production. Deletion of the predicted aminotransferase sidA abolished production of the carboxamides siderochelin A/B and led to the accumulation of the carboxylate siderochelin D. Finally, we deleted the predicted hydroxylase sidB and established that it is essential for siderochelin production. Our findings show that microbial coculture can successfully activate silent BGCs and lead to the discovery and characterization of unknown BGCs for molecules like siderochelin.IMPORTANCESiderophores are vital iron-acquisition elements required by microbes for survival in a variety of environments. Furthermore, many siderophores are essential for the virulence of various human pathogens, making them a possible target for antibacterials. The significance of our work is in the identification and characterization of the previously unknown BGC for the siderophore siderochelin. Our work adds to the growing knowledge of siderophore biosynthesis, which may aid in the future development of siderophore-targeting pharmaceuticals and inform on the ecological roles of these compounds. Furthermore, our work demonstrates that combining microbial coculture with metabolomics is a valuable strategy for identifying upregulated compounds and their BGCs.

A retrospective study revealing complex viral diversity and a substantial burden of HPV infection in SARS-CoV-2 positive individuals, Sierra Leone

BackgroundThe COVID-19 pandemic has underscored the critical role of sequencing technology in disease control and outbreak response. However, resource limitations and challenging environments often impede such efforts in low and middle-income countries. This study aimed to investigate the spectrum of viral co-infections, particularly with human viral pathogens, in SARS-CoV-2 positive individuals in Sierra Leone using metagenomic sequencing, evaluating the feasibility of utilizing this technology for epidemiological and evolutionary surveillance of pathogens related to public health in low-income environments.MethodsWe retrospectively collected and analyzed 98 nasopharyngeal swab specimens from SARS-CoV-2 positive individuals in Sierra Leone. Samples were pre-processed locally and transferred to China via FTA cards for metagenomic sequencing, which was performed using the Novaseq platform. The study focused on the identification of nasopharyngeal viruses co-infecting with SARS-CoV-2, with a deeper analysis of significant human viral pathogens such as HPV.ResultsThe study identified 22 viral taxa from 20 families, including 4 human viruses. Notably, 19.4% of samples showed HPV co-infection with 34 distinct types, predominantly beta and gamma HPVs. Multiple HPV types were found in individual samples, indicating a high complexity of viral co-infections.ConclusionsThe identification of a wide range of co-infecting viruses, particularly multiple HPV genotypes, highlights the complexity of viral interactions and their potential implications for public health. These findings enhance our understanding of viral co-infections and provide valuable insights for public health interventions in Sierra Leone. Further research is needed to explore the clinical significance of these findings and their impact on disease outcomes.

Adult sickle cell disease and SARS-CoV-2: an increasingly common comorbidity for a rare disease

Sickle cell disease (SCD) is a collection of genetic lesions that manifest in the diminished effectiveness of hemoglobin. We collected and reviewed the recent and extant literature on SARS-CoV-2 (COVID-19) and SCD. We posit an answer to the question associated with any adaptive responses to COVID-19 in individuals with SCD. We collected papers from MEDLINE and all available published papers on COVID-19 and SCD. Unlike a formal meta-analysis, given the early phase of this review in the pandemic, we did not seek unpublished papers. We found an emerging literature where case studies dominated, and traditional large N epidemiological studies were absent. Patients with SCD share many comorbid illnesses with an increased risk of mortality associated with contracting COVID-19. There is sufficient empirical justification to accelerate research on the impact of a viral pathogen like COVID-19 on individuals with SCD. *************************************************************** List of all authors: Michaela Boggan,1,2,3 Christopher L. Edwards,1,2,3 Jordan Meek,1,2,3 Mary Wood,4 W. Jeff Bryson,5 John J. Sollers,1,2,3 Debra O. Parker,1,2,3 Camela S. Barker,2,5 Jessica Miller,2,6 Brianna Downey,2,5 Asha Lockett,2,5 Jazmin Rosales,1,2,3 Courtney Munroe, Jr.,2 Noa Wax,2,5 Sharena Scott,1,2,3 Bridget Pittman,1,2,3 Merell Turner,1,2,3 Hillary T. Dietahin,1,2,3 Eric Smith,1,2,3 Alexandria McDougald,1,2,3 Samantha Beavers,1,2,3 Lakaiya Meadows,1,2,3 Maya Walker,1,2,3 Andrea Richardson,1,2,3 John J. Sollers, IV,2,8 Grace D. Donahue,2,8 Goldie Byrd,7 Malik Muhammad,1,2 Alvin Kidd,9 Walter Charles,1,2 Jonathan Livingston,1,2,3 Shiv Sudhakar10 1North Carolina Central University; 2NCCU Psychoneuroendocrine and Rare Diseases Laboratory; 3NCCU Debra O. Parker Research Incubator; 4Duke University Medical Center; 5Fielding Graduate University; 6Bridges Point Sickle Cell Foundation; 7Wake Forest Medical Center; 8Thomas Moore University; 9Livingston College; 10California Northstate University, United States

NIR‐II AIEgens for Infectious Diseases Phototheranostics

Pathogenic infectious diseases have persistently posed significant threats to public health. Phototheranostics, which combines the functions of diagnostic imaging and therapy, presents an extremely promising solution to block the spread of pathogens as well as the outbreak of epidemics owing to its merits of a wide‐spectrum of activity, high controllability, non‐invasiveness, and difficult to acquire resistance. Among multifarious phototheranostic agents, second near‐infrared (NIR‐II, 1000–1700 nm) aggregation‐induced emission luminogens (AIEgens) are notable by virtue of their deep penetration depth, excellent biocompatibility, balanced radiative and nonradiative decay and aggregation‐enhanced theranostic performance, making them an ideal option for combating pathogens. This minireview provides a systematical summary of the latest advancements in NIR‐II AIEgens with emphasis on the molecular design and nanoplatform formulation to fulfill high‐efficiency in treating bacterial and viral pathogens, classified by disease models. Then, the current challenges, potential opportunities, and future research directions are presented to facilitate the further progress of this emerging field.

NIR-II AIEgens for Infectious Diseases Phototheranostics.

Pathogenic infectious diseases have persistently posed significant threats to public health. Phototheranostics, which combines the functions of diagnostic imaging and therapy, presents an extremely promising solution to block the spread of pathogens as well as the outbreak of epidemics owing to its merits of a wide-spectrum of activity, high controllability, non-invasiveness, and difficult to acquire resistance. Among multifarious phototheranostic agents, second near-infrared (NIR-II, 1000-1700 nm) aggregation-induced emission luminogens (AIEgens) are notable by virtue of their deep penetration depth, excellent biocompatibility, balanced radiative and nonradiative decay and aggregation-enhanced theranostic performance, making them an ideal option for combating pathogens. This minireview provides a systematical summary of the latest advancements in NIR-II AIEgens with emphasis on the molecular design and nanoplatform formulation to fulfill high-efficiency in treating bacterial and viral pathogens, classified by disease models. Then, the current challenges, potential opportunities, and future research directions are presented to facilitate the further progress of this emerging field.

Highly pathogenic avian influenza virus H5N1 clade 2.3.4.4b in wild rats in Egypt during 2023

ABSTRACT We detected highly pathogenic avian influenza A(H5N1) virus in wild rats collected from a rural area in Giza, Egypt, near poultry farms, markets, and backyard flocks. Sequence and phylogenetic analyses indicated that the virus from the rats belonged to clade 2.3.4.4b, which has been the predominant virus genotype circulating in Egypt and worldwide since 2021-2022. Active surveillance of avian influenza viruses in wild and domestic mammals is recommended to prevent further spread to mammals and humans.

Photochemical Action of Far‐UVC Radiation (222 nm) in Wastewater Treatment and Indoor Air Disinfection

Ultraviolet‐ C irradiation can effectively disinfect various pathogens present in air, surfaces, and water. Various recent research studies suggest use of KrCl* (krypton‐chloride) excimer lamps to disinfect high‐risk public spaces having pathogenic bateria and viruses, as they emit Far‐UVC radiation (222 nm) with lower health risks than germicidal UVC (254 nm). The purification of water and air having pollutants and pathogens is a critical challenge in environmental protection and public health assurance. Far‐UVC excimer lamps (222 nm) have shown potential in decontaminating various organic pollutants, however, their efficacy against inorganic pollutants present in wastewater and indoor air as well as associated chemistry requires further investigations for wider acceptance. This review examines various photochemical action of Far‐UVC radiation (222 nm) in wastewater treatment and indoor air disinfection, elaborating their potential for inorganic pollutant removal in wastewater as well as challenges associated with their application in disinfection of indoor air.

Definition of a concentration and RNA extraction protocol for optimal whole genome sequencing of SARS-CoV-2 in wastewater (ANRS0160)

Monitoring the presence of RNA from emerging pathogenic viruses, such as SARS-CoV-2, in wastewater (WW) samples requires suitable methods to ensure an effective response. Genome sequencing of WW is one of the crucial methods, but it requires high-quality RNA in sufficient quantities, especially for monitoring emerging variants. Consequently, methods for viral concentration and RNA extraction from WW samples have to be optimized before sequencing. The purpose of this study was to achieve high coverage (≥ 90 %) and sequencing depth (at least ≥200×) even for low initial RNA concentrations (< 105 genome copies (GC)/L) in WW. A further objective was to determine the range of SARS-CoV-2 RNA concentrations that allow high-quality sequencing, and the optimal sample volume for analysis. Ultrafiltration (UF) methods were used to concentrate viral particles from large influent samples (up to 500 mL). An RNA extraction protocol using silica beads, neutral phenol-chloroform treatment, and a PCR inhibitor removal kit was chosen for its effectiveness in extracting RNA and eliminating PCR inhibitors, as well as its adaptability for use with large influent samples. Recovery rates ranged from 24 % to 63 % (N = 17) for SARS-CoV-2 naturally present in WW samples. 200 mL WW samples can be enough for UF concentration, as they showed high quality sequencing analyses with between 5 × 104 GC/L and 6 × 103 GC/L. Below 6 × 103 GC/L, high-quality sequencing was also achieved for ∼40 % of the samples using 500 mL of WW. Sequencing analysis for variant detection was performed on 200 mL WW samples with coverage of >95 % and sequencing depth of >1000×. Analyses revealed the predominance of variant EG.5, known as Eris (66 %–100 %). The use of UF methods in combination with a suitable RNA extraction protocol appear promising for sequencing enveloped viruses in WW in a context of viral emergence.

Pathogen-driven Pseudomonas reshaped the phyllosphere microbiome in combination with Pseudostellaria heterophylla foliar disease resistance via the release of volatile organic compounds

BackgroundContinuous monocropping obstacles are common in plants, especially medicinal plants, resulting in disease outbreaks and productivity reductions. Foliar disease, mainly caused by Fusarium oxysporum, results in a severe decrease in the yield of Pseudostellaria heterophylla annually. Determining an effective biomethod to alleviate this disease is urgently needed to improve its productivity and quality.ResultsThis study screened thirty-two keystone bacterial genera induced by pathogens in P. heterophylla rhizosphere soil under continuous monocropping conditions. Pseudomonas, Chryseobacterium, and Flavobacterium, referred to as the beneficial microbiota, were significantly attracted by pathogen infection. The P. palleroniana strain B-BH16-1 can directly inhibit the growth and spore formation of seven primary pathogens of P. heterophylla foliar disease by disrupting fusaric acid production via the emission of volatile organic compounds (VOCs). In addition, strain B-BH16-1 enhances the disease resistance of P. heterophylla by obliterating the pathogen and assembling beneficial microbiota.ConclusionPathogen-induced Pseudomonas reshaped phyllosphere microbial communities via direct antagonism of pathogens and indirect disruption of the pathogen virulence factor biosynthesis to enhance disease suppression and improve yields. These results show that inhibiting pathogen virulence biosynthesis to reshape the plant microbial community using disease-induing probiotics will be an innovative strategy for managing plant disease, especially under continuous monoculture conditions.

The Response of Murine Gut Microbiome in the Presence of Altered rpoS Gene of Klebsiella pneumoniae.

The murine model is invaluable for studying intricate interactions among gut microbes; hosts; and diseases. However; the impact of genetic variations in the murine microbiome; especially in disease contexts such as Klebsiella pneumoniae (Kp) infection; still needs to be explored. Kp; an opportunistic global pathogen; is becoming increasingly prevalent in regions like Asia; especially China. This study explored the role of the gut microbiota during Kp infection using mouse model; including wild-type and rpoS mutants of Kp138; KpC4; and KpE4 from human; maize; and ditch water; respectively. Under stress conditions; RpoS reconfigures global gene expression in bacteria; shifting the cells from active growth to survival mode. Our study examined notable differences in microbiome composition; finding that Lactobacillus and Klebsiella (particularly in WKp138) were the most abundant genera in mice guts at the genus level in all wild-type treated mice. In contrast; Firmicutes were predominant in the healthy control mice. Furthermore; Clostridium was the dominant genus in all mutants; mainly in ∆KpC4; and was absent in wild-type treated mice. Differential abundance analysis identified that these candidate taxa potentially influence disease progression and pathogen virulence. Functional prediction analysis showed that most bacterial groups were functionally involved in biosynthesis; precursor metabolites; degradation; energy generation; and metabolic cluster formation. These findings challenge the conventional understanding and highlight the need for nuanced interpretations in murine studies. Additionally; this study sheds light on microbiome-immune interactions in K. pneumoniae infection and proposes new potential therapeutic strategies.

Saliva-STAT: Sample-to-answer saliva test for COVID-19

Highly accessible and highly accurate diagnostics are necessary to combat rapidly-spreading infectious diseases, such as the recent COVID-19 pandemic. While lateral flow antigen tests have become pervasive, they are insufficiently sensitive to detect early or asymptomatic disease. Nucleic acid amplification tests provide the needed sensitivity, but accessibility of these tests continues to be a challenge due to the need for precise sample processing steps. Here we report a sample-to-answer test for saliva samples (saliva-STAT) that utilizes a battery-powered handheld instrument and a low-cost easily-manufacturable sample cassette to perform a nucleic acid amplification test for viral pathogens. To enable a completely automated assay, we leverage thermally responsive alkane partitions (TRAPs) and paramagnetic beads for virus purification and concentration, as well as reagent addition and mixing. Notably, the saliva STAT easily accommodates directly-dispensed saliva samples (in contrast to microfluidic devices), which is necessary for self-testing. Using the saliva-STAT platform, we demonstrate detection of down to 0.2 copies/μL of SARS-CoV-2 virus in saliva samples. We envision that the saliva-STAT could be used in walk-in clinics, mobile clinics, public testing locations, and in the home. With minor adjustments to the assay, the saliva-STAT platform can easily be adapted for other respiratory viruses, such as Influenza.

Efficient concentration of viral nucleic acid in wastewater through surfactant releasing and a two-step magnetic bead extraction and purification

Wastewater-based epidemiology (WBE) is a valuable complement to clinical monitoring, allowing for effective surveillance of viral infections in populations, and tracking the presence and the epidemiological dynamics of various infectious pathogens in communities. However, virus loads are usually low-abundant in wastewater, and current virus concentration methods for WBE are laborious and time-consuming with low recovery efficiency. To address these challenges, we have developed a magnetic bead-based semi-automated method involving extraction and purification to directly concentrate viral nucleic acids from sewage within 55 min. Prior to concentration, 0.5 % LDS was introduced to pretreat wastewater to inactivate viruses and release viral nucleic acids from both liquid and solid fractions to improve recovery. Under optimal conditions, the concentration method combined with reverse transcription-quantitative polymerase chain reaction (RT-qPCR) can detect severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA added exogenously in wastewater as low as 4.9 copies/mL within 2.5 h, with an average recovery rate exceeding 80 %. Testing real sewages proved the applicability of the method to detect multiple viruses in different sewages. Additionally, variants of SARS-CoV-2 were successfully identified by multiplex amplicon sequencing in two samples. In conclusion, the new method could provide a much more efficient way for WBE of pathogenic viruses in various sewages.

Interferon-stimulated genes and their antiviral activity against SARS-CoV-2.

The coronavirus disease 2019 (COVID-19) pandemic remains an international health problem caused by the recent emergence of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). As of May 2024, SARS-CoV-2 has caused more than 775 million cases and over 7 million deaths globally. Despite current vaccination programs, infections are still rapidly increasing, mainly due to the appearance and spread of new variants, variations in immunization rates, and limitations of current vaccines in preventing transmission. This underscores the need for pan-variant antivirals and treatments. The interferon (IFN) system is a critical element of the innate immune response and serves as a frontline defense against viruses. It induces a generalized antiviral state by transiently upregulating hundreds of IFN-stimulated genes (ISGs). To gain a deeper comprehension of the innate immune response to SARS-CoV-2, its connection to COVID-19 pathogenesis, and the potential therapeutic implications, this review provides a detailed overview of fundamental aspects of the diverse ISGs identified for their antiviral properties against SARS-CoV-2. It emphasizes the importance of these proteins in controlling viral replication and spread. Furthermore, we explore methodological approaches for the identification of ISGs and conduct a comparative analysis with other viruses. Deciphering the roles of ISGs and their interactions with viral pathogens can help identify novel targets for antiviral therapies and enhance our preparedness to confront current and future viral threats.

Exploring waterborne viruses in groundwater: Quantification and Virome characterization via passive sampling and targeted enrichment sequencing

Aquifers, which provide drinking water for nearly half the world's population, face significant challenges from microbial contamination, particularly from waterborne viruses such as human adenovirus (HAdV), norovirus (NoV) and enterovirus (EV). This study, conducted as part of the UPWATER project, investigates the sources of urban groundwater contamination using viral passive sampling (VPS) and target enrichment sequencing (TES). We assessed the abundance of eight viral pathogens (HAdV, EV, NoV genogroup I and II, rotavirus, influenza A virus, hepatitis E virus and SARS-CoV-2) and investigated the virome diversity of groundwater in the aquifer of the Besòs River Delta in Catalonia. Over a period of 7 months, we collected 114 samples from the aquifer using nylon and nitrocellulose membranes to adsorb viruses over a 10-day period. Human faecal contamination was detected in nearly 50 % of the groundwater samples, with mean HAdV total counts ranging from 1.23E+02 to 3.66E+03 GC, and occasional detections of EV and NoV GI and GII. In addition, deep sequencing revealed a diverse virome in the aquifer, with detection of human pathogens, including adenovirus, astrovirus, calicivirus, enterovirus, herpesvirus, papillomavirus and rotavirus. Time-integrated sampling using VPS increases the likelihood of virus detection and, when combined with TES, can provide a deeper understanding of virus prevalence in this important water compartment. This approach is expected to streamline long-term monitoring efforts and enable small communities or water managers with limited resources to effectively manage their groundwater reservoirs.

Antimicrobial Activity of Gallium(III) Compounds: Pathogen-Dependent Targeting of Multiple Iron/Heme-Dependent Biological Processes.

Metals play vital roles in biological systems, with iron/heme being essential for cellular and metabolic functions necessary for survival and/or virulence in many bacterial pathogens. Given the rise of bacterial resistance to current antibiotics, there is an urgent need for the development of non-toxic and novel antibiotics that do not contribute to resistance to other antibiotics. Gallium, which mimics iron, has emerged as a promising antimicrobial agent, offering a novel approach to combat bacterial infections. Gallium does not have any known functions in biological systems. Gallium exerts its effects primarily by replacing iron in redox enzymes, effectively inhibiting bacterial growth by targeting multiple iron/heme-dependent biological processes and suppressing the development of drug resistance. The aim of this review is to highlight recent findings on the mechanisms of action of gallium and provide further insights into the development of gallium-based compounds. Understanding the mechanisms underlying gallium's biological activities is crucial for designing drugs that enhance their therapeutic therapies while minimizing side effects, offering promising avenues for the treatment of infectious diseases.

Assessment of microbial safety of fresh vegetables through Caenorhabditis elegans model

Caenorhabditis elegans is widely used as a model to predict the virulence of animal-origin human pathogens, as C. elegans and humans share similar intestinal epithelial cells. A study was undertaken to assess the feasibility of C. elegans for surveillance of foodborne pathogens in fresh vegetables. First, the virulent strains of four foodborne pathogens viz., Pseudomonas aeruginosa (PAO1), Escherichia coli (O157), Salmonella enterica (CI1), and Staphylococcus aureus (ATCC25923) were fed to the worm as sole diet and compared the survival, phenome traits, and gut integrity with standard E. coli OP50. Secondly, the vegetable surface microbiota (tomato) was enriched with gradient concentrations of PAO1, and the worm's survival and gut distension and leakage were assessed. Thirdly, the total microbiota of fresh vegetables (tomato, brinjal, and lablab) were evaluated for the worm's survival. The gut epithelial cell damage and leakage were monitored by blue dye-based smurf assay. Foodborne pathogens reduced the median lifespan (LT50) of the worm drastically, with PAO1 had 2.5 days, O157 (6 days), CI1 (8 days), ATCC25923 (6 days), while the standard diet OP50 had 16 days. The phenome traits of worms, viz., pharyngeal pumping, defecation cycle, body bends, head thrashes, touch stimulus, paralysis, gut leakage, and reproduction, were significantly negatively affected due to pathogen feeding. The gut epithelial integrity was severely affected, and blue dye leakage was the highest in O157 (73 %), followed by PAO1 (55 %), CI1 (40 %) and ATCC25923 (38 %), while the gut epithelial cells were intact in OP50 fed worms. The pathogen enrichment in tomato surface microbiota diet showed that LT50 of the worms was reduced from 8 days to 2.5 days and 10 to 8 days with increasing gradient of PAO1 in fresh tomato microbiota and 24-hours pre-enriched tomato microbiota, respectively. Smurf test also confirmed that an increase in PAO1 proportion in total microbiota distended the gut with high dye leakage. The total microbiota extracted from tomato, brinjal, and lablab did not affect the worm's health and had an extended median life span (11 – 13 days) when they were devoid of any foodborne pathogens. These findings provide a novel and straightforward approach for assessing foodborne pathogens using animal models.

Quantifying the seasonal reproductive cycle in three species of Malagasy fruit bats with implications for pathogen and population dynamics.

Bats (order Chiroptera) are hosts for highly virulent zoonotic pathogens. Many bats demonstrate seasonally varying antiviral responses, including antibody responses which have been observed to peak during the nutritionally depleted dry-season and female gestation periods, suggesting some impact of resource deficits on bat virus immunity. Given the frequent overlap in these energetically demanding periods, it is likely that endocrinological changes associated with pregnancy might partially explain the aforementioned pattern in antibody dynamics. Regardless, we know little about the seasonality of reproduction in many fruit bat species, despite the importance of reproductive biology to informing conservation management (e.g. population viability) and disease dynamics. Here, we aimed to elucidate the reproductive biology of three species of endemic fruit bat native to the island of Madagascar: Pteropus rufus, Eidolon dupreanum, and Rousettus madagascarensis. To do so, we leveraged plasma samples collected in part with a longitudinal field study, from 2018 to 2020. We adapted three standard reproductive assays previously validated in humans to quantify seasonal changes in reproductive hormones for bats and applied a mixture model approach to determine hormone cutoffs for pregnancy. As expected, we found that pregnant females showed the highest levels of estradiol and progesterone and adult males the highest levels of testosterone. Additionally, female P. rufus and R. madagascariensis showed clear seasonality in reproduction with peaks in estradiol and progesterone in August and October, respectively. Seasonality was less clearly discernible in the female E. dupreanum and male data. In general, we found that the commercially available assays were successful in quantifying endocrinological hormones for bats; when paired with histological embryo sections or field data, these offer a powerful tool to elucidate bat reproductive calendars.

Development of Fusion-Based Assay as a Drug Screening Platform for Nipah Virus Utilizing Baculovirus Expression Vector System.

Nipah virus (NiV) is known to be a highly pathogenic zoonotic virus, which is included in the World Health Organization Research & Development Blueprint list of priority diseases with up to 70% mortality rate. Due to its high pathogenicity and outbreak potency, a therapeutic countermeasure against NiV is urgently needed. As NiV needs to be handled within a Biological Safety Level (BSL) 4 facility, we had developed a safe drug screening platform utilizing a baculovirus expression vector system (BEVS) based on a NiV-induced syncytium formation that could be handled within a BSL-1 facility. To reconstruct the NiV-induced syncytium formation in BEVS, two baculoviruses were generated to express recombinant proteins that are responsible for inducing the syncytium formation, including one baculovirus exhibiting co-expressed NiV fusion protein (NiV-F) and NiV attachment glycoprotein (NiV-G) and another exhibiting human EphrinB2 protein. Interestingly, syncytium formation was observed in infected insect cells when the medium was modified to have a lower pH level and supplemented with cholesterol. Fusion inhibitory properties of several compounds, such as phytochemicals and a polysulfonated naphthylamine compound, were evaluated using this platform. Among these compounds, suramin showed the highest fusion inhibitory activity against NiV-induced syncytium in the baculovirus expression system. Moreover, our in silico results provide a molecular-level glimpse of suramin's interaction with NiV-G's central hole and EphrinB2's G-H loop, which could be the possible reason for its fusion inhibitory activity.

In situ oxygen-generating bio-heterojunctions for enhanced anti-bacterial treatment of anaerobe-induced periodontitis

Periodontitis, a chronic inflammatory condition associated with bacterial infection, is the leading cause of tooth loss in adults. Pathogenic bacteria that persist in deep periodontal pockets with hyperglycemic levels following traditional manual debridement can contribute to a persistent local inflammatory microenvironment, posing a significant challenge and highlighting the critical need for improved therapeutic approaches. In addition, the anaerobic environment during these treatments is beneficial to the colonization of anaerobes and may amplify inflammatory responses. Herein, we designed a glucose oxidase (GOx)-coating MXene-SnS2 bio-heterojunctions (MS@G bio-HJs) for multi-modal and effective treatment of anti-bacteria and anti-inflammatory. Upon the hyperglycemic nidus in periodontal pockets, GOx catalyzes the conversion of glucose into hydrogen peroxide (H2O2). Subsequently, the breakdown of H2O2 into hydroxyl radicals through Sn2+/Sn4+-involved Fenton-like reactions enables in situ liberation of oxygen (O2), contributing to relieve local hypoxia. The proposed bio-HJs presents a satisfactory bactericidal capability with anti-bacterial rates of more than 99 % upon near-infrared irradiation, in virtue of multi-modal therapies including photodynamic, photothermal and chemodynamic treatments. Furthermore, in vivo assays utilizing infectious rat models demonstrated that the proposed bio-HJs exhibits high biocompatibility and capacity to alleviate hypoxia and reduce pathogenic virulence factors, potentially contributing to periodontal tissue regeneration. These findings suggest that the versatile bio-HJs could be a promising therapeutic candidate for treating infectious periodontal diseases.