High Pathogen Research Articles

MTSv: rapid alignment-based taxonomic classification and high-confidence metagenomic analysis.

As the size of reference sequence databases and high-throughput sequencing datasets continue to grow, it is becoming computationally infeasible to use traditional alignment to large genome databases for taxonomic classification of metagenomic reads. Exact matching approaches can rapidly assign taxonomy and summarize the composition of microbial communities, but they sacrifice accuracy and can lead to false positives. Full alignment tools provide higher confidence assignments and can assign sequences from genomes that diverge from reference sequences; however, full alignment tools are computationally intensive. To address this, we designed MTSv specifically for alignment-based taxonomic assignment in metagenomic analysis. This tool implements an FM-index assisted q-gram filter and SIMD accelerated Smith-Waterman algorithm to find alignments. However, unlike traditional aligners, MTSv will not attempt to make additional alignments to a TaxID once an alignment of sufficient quality has been found. This improves efficiency when many reference sequences are available per taxon. MTSv was designed to be flexible and can be modified to run on either memory or processor constrained systems. Although MTSv cannot compete with the speeds of exact k-mer matching approaches, it is reasonably fast and has higher precision than popular exact matching approaches. Because MTSv performs a full alignment it can classify reads even when the genomes share low similarity with reference sequences and provides a tool for high confidence pathogen detection with low off-target assignments to near neighbor species.

Green synthesis of copper nanoparticles and their formulation into face masks: An antibacterial study

AbstractWe report the facile ultrasound‐assisted synthesis of copper nanoparticles (CuNPs) using blueberries extract (Vaccinium corymbosum) under environmental conditions and their incorporation into face masks as an effective antibacterial additive. For this purpose, the hydro‐alcoholic blueberry extract was combined 1:1 with a metal precursor (CuSO4). The chemical reduction process was improved by ultrasound‐assisted method for 30 min, obtaining semispherical CuNPs ranging ca. 3–12 nm employing TEM analysis. Freshly synthesized CuNPs were characterized by UV–Vis spectra, demonstrating the characteristic SPR absorption band at 535 nm. XRD patterns of CuNPs powder revealed the crystalline structure FCC of CuNPs, without CuO/CuO2 species. Antibacterial activity (AA) of biosynthesized CuNPs was evaluated against two high virulence pathogens: Gram‐positive Staphylococcus aureus and Gram‐negative Pseudomonas aeruginosa, after 1 and 3 h of contact, showing a MIC of 200 μg/ml, and a CMB of 400 μg/ml. To validate the potential biological application of CuNPs were incorporated into PES fibers and deposited at the surface of non‐woven face masks against Escherichia coli and the airborne bacteria S. aureus, demonstrating their high antibacterial capacity after 24 h. Our results represent a facile and green method to produce high amounts of antibacterial CuNPs (yield ca. 1 g/L of reaction), with potential application as an effective additive for antimicrobial coatings formulation.

Recurring infection by crayfish plague pathogen only marginally affects survival and growth of marbled crayfish

Invasive alien crayfish threaten the diversity of freshwater ecosystems and native crayfish fauna. In Europe, this is largely due to transmission of the crayfish plague to susceptible native crayfish. Many invasive species tolerate crayfish plague, but the infection still has the potential to reduce the fitness of a tolerant host due to energy trade-offs between immune response maintenance and life-history traits, such as growth and reproduction. In combination with other unfavourable conditions, such a response could alter further invasion success of an otherwise successful crayfish invader. We examined whether repeated infection with one of the most virulent haplogroups of crayfish plague agent (Aphanomyces astaci) affects growth or survival of the juvenile marbled crayfish (Procambarus virginalis). Juveniles were exposed to i) two levels of pathogen concentrations, and ii) two different feeding regimes under the higher pathogen concentration. In all performed trials, repeated infection reduced growth rates, while the combination of recurring infection and food limitation significantly increased mortality. The average energy cost of the immune response was estimated at 12.07 J/day for individuals weighing 0.3 grams. Since infections were frequent and pathogen concentrations high, results suggest that marbled crayfish is resistant to A. astaci pathogen and its survival is only affected by adding the stress of food limitation. The survival of almost half of the individuals exposed to high pathogen loads and extreme food limitation indicates that chronic infection by crayfish plague is unlikely to be an important factor impeding invasion success of the marbled crayfish, even under harsh conditions. Our results add to the growing body of evidence that marbled crayfish has potential to become one of the most successful freshwater invaders.

First isolation of a trh positive V. alginolyticus from Atlantic bluefin tuna (Thunnus thynnus) farmed in Turkey

Popularity of sushi-sashimi (raw-almost raw fish service) is increasing around the globe, and Atlantic bluefin tuna is among the most frequently used fish in these dishes. In this study, trh (Thermostable direct hemolysin-related hemolysin gene) positive Vibrio alginolyticus was isolated from the internal organs of two tuna sent to the laboratory from a farm in Aegean region of Turkey in 2014. Isolation was done by conventional microbiological methods and Vitek 2 Compact fully automatic identification device was used for identification. Isolate confirmation and investigation of trh-tdh (Thermostable direct hemolysin) gene existence were carried out by a Polymerase Chain Reaction (PCR) method. Two V.alginolyticus isolates from two tuna were found to be trh positive and tdh negative. trh is one of the important genes associated with pathogenicity in the Vibrio genus, and raw consumption of tuna infected with trh positive V.alginolyticus can cause serious food poisoning. The aim of this study is to report first isolation of trh positive Vibrio alginolyticus from two bluefin tuna cultured in the Aegean sea, to draw attention to possible dangers in raw-almost raw fish consumption and supply information for further epidemiological studies. However, more samples are necesary for mentioning the prevalence of high virulence food pathogens in tuna. However, due to their economic value, multiple tuna samples are rarely sent to laboratories for diagnostic purposes.

The OsCBL8-OsCIPK17 Module Regulates Seedling Growth and Confers Resistance to Heat and Drought in Rice.

The calcium signaling pathway is critical for plant growth, development, and response to external stimuli. The CBL–CIPK pathway has been well characterized as a calcium-signaling pathway. However, in most reports, only a single function for this module has been described. Here, we examined multiple functions of this module. CIPK showed a similar distribution to that of CBL, and OsCBL and OsCIPK families were retained after experiencing whole genome duplication events through the phylogenetic and synteny analysis. This study found that OsCBL8 negatively regulated rice seed germination and seedling growth by interacting with OsCIPK17 with overexpression and gene editing mutant plants as materials combining plant phenotype, physiological indicators and transcriptome sequencing. This process is likely mediated by OsPP2C77, which is a member of the ABA signaling pathway. In addition, OsCBL mediated the targeting of OsNAC77 and OsJAMYB by OsCIPK17, thus conferring resistance to high temperatures and pathogens in rice. Our work reveals a unique signaling pathway, wherein OsCBL8 interacts with OsCIPK17 and provides rice with multiple resistance while also regulating seedling growth.

Severe mammarenaviral disease in guinea pigs effectively treated by an orally bioavailable fusion inhibitor, alone or in combination with favipiravir

Infections by pathogenic New World mammarenaviruses (NWM)s, including Junín virus (JUNV), can result in a severe life-threatening viral hemorrhagic fever syndrome. In the absence of FDA-licensed vaccines or antivirals, these viruses are considered high priority pathogens. The mammarenavirus envelope glycoprotein complex (GPC) mediates pH-dependent fusion between viral and cellular membranes, which is essential to viral entry and may be vulnerable to small-molecule inhibitors that disrupt this process. ARN-75039 is a potent fusion inhibitor of a broad spectrum of pseudotyped and native mammarenaviruses in cell culture and Tacaribe virus infection in mice. In the present study, we evaluated ARN-75039 against pathogenic JUNV in the rigorous guinea pig infection model. The compound was well-tolerated and had favorable pharmacokinetics supporting once-per-day oral dosing in guinea pigs. Importantly, significant protection against JUNV challenge was observed even when ARN-75039 was withheld until 6 days after the viral challenge when clinical signs of disease are starting to develop. We also show that ARN-75039 combination treatment with favipiravir, a viral polymerase inhibitor, results in synergistic activity in vitro and improves survival outcomes in JUNV-challenged guinea pigs. Our findings support the continued development of ARN-75039 as an attractive therapeutic candidate for treating mammarenaviral hemorrhagic fevers, including those associated with NWM infection.

Development of a droplet digital PCR method for the sensitive detection and quantification of largemouth bass ranavirus.

Largemouth bass ranavirus (LMBRaV), also known as largemouth bass virus (LMBV), is a high mortality pathogen in largemouth bass. A rapid, sensitive, specific and convenient diagnosis method is an urgent requirement for the prevention of virus transmission. In the present study, a droplet digital PCR (ddPCR) method based on the major capsid protein (mcp) gene was established to detect and quantify the virus genome copy number. Oligonucleotide primers were designed based on the LMBRaV mcp gene sequence. The specificity and sensitivity of ddPCR assay were analysed. The other aquatic virus including Chinese giant salamander iridovirus (GSIV), Cyprinid herpesvirus II (CyHV-2) and infectious spleen and kidney necrosis virus could not be detected by LMBRaV ddPCR assay. The detection limit of ddPCR assay was 2 ± 0.37 copies/μl DNA sample. And this ddPCR assay had great repeatability and reproducibility. In clinical diagnosis of 50 largemouth bass, 43 positive samples were detected by ddPCR, whereas only 34 positive samples were detected by quantitative PCR (qPCR). This LMBRaV detection assay provided a specific and sensitive method for the rapid diagnosis of LMBRaV infection in largemouth bass as well as quantification of the virus load.

Persistence of surrogates for high consequence viral and bacterial pathogens in a pilot-scale activated sludge treatment system.

The persistence of high consequence public health pathogens in a wastewater treatment system can significantly impact worker safety, as well as the public and downstream water bodies, particularly if the system is forced to shut down the treatment processes. This study utilizes organism viability to compare the persistence of three pathogen surrogates in wastewater using a pilot-scale activated sludge treatment (AST) system, operated to mimic treatment processes of large-scale plants. Bacillus globigii spores, surrogate for Bacillus anthracis, persisted in the AST system for at least a 50-day observation period leading to a possible steady condition far beyond the solid retention time for sludge particles. MS2 bacteriophage, surrogate for Poliovirus and other non-enveloped enteric viruses, was observed for up to 35 days after introduction, which largely and expectedly correlated to the measured solid retention time. Phi-6 bacteriophage, a surrogate for Ebola virus and other enveloped viruses, was detected for no more than 4 days after introduction, even though the AST system was operated to provide three times slower solids removal than for the other surrogates. This suggests Phi-6 is subject to inactivation under AST conditions rather than physical removal. These results may suggest similar persistence for the surrogated pathogens, leading to appropriate consequence management actions.

Heat shock transcriptional factors (HSFs) are expressed in response to hydrogen peroxide production in grapevines inoculated with Colletotrichum Species

Heat shock transcriptional factors (HSFs) are expressed in plants due to external stress, high temperatures, or pathogenic infections. This study was undertaken to analyze the expression of HSF genes in grapevines inoculated with pathogens. Spores of Colletotrichum acutatum and C. gloeosporioides were inoculated on the leaves, and on immature and mature fruits of ‘Campbell Early’ and creeping grapevine (Vitis flexuosa). The real-time PCR of RNA isolated from infected leaves and fruits showed specific upregulation of HSF11, HSF12, HSF14, and HSF15 subsequent to both high temperature and pathogen infections. However, HSF16 and HSF17 were up-regulated specifically by pathogenic infections only and showed different expression patterns in response to wounding. Among the hydrogen peroxide-related genes, the expression of catalase (CAT) and superoxide dismutase (SOD) was up-regulated by pathogen infections. Concurrently, expression of six HSFs (HSF11, HSF12, HSF14, HSF15, HSF16, and HSF17) dose-dependently increased with accumulation of hydrogen peroxide in the leaves and fruits of grapevines. The expression of selected HSF genes was up-regulated differentially as a defense reaction in ‘Campbell Early’ and V. flexuosa grapevine in response to external stress (such as wounding) and pathogen inoculation. This indicates that expression of some HSFs is regulated through the hydrogen peroxide-mediated pathways in response to pathogens. Further studies determining the mechanism of HSF gene expression induced by external stress are required.

A neutrophil-B-cell axis impacts tissue damage control in a mouse model of intraabdominal bacterial infection via Cxcr4.

Sepsis is a life-threatening condition characterized by uncontrolled systemic inflammation and coagulation, leading to multiorgan failure. Therapeutic options to prevent sepsis-associated immunopathology remain scarce. Here, we established a mouse model of long-lasting disease tolerance during severe sepsis, manifested by diminished immunothrombosis and organ damage in spite of a high pathogen burden. We found that both neutrophils and B cells emerged as key regulators of tissue integrity. Enduring changes in the transcriptional profile of neutrophils include upregulated Cxcr4 expression in protected, tolerant hosts. Neutrophil Cxcr4 upregulation required the presence of B cells, suggesting that B cells promoted disease tolerance by improving tissue damage control via the suppression of neutrophils' tissue-damaging properties. Finally, therapeutic administration of a Cxcr4 agonist successfully promoted tissue damage control and prevented liver damage during sepsis. Our findings highlight the importance of a critical B-cell/neutrophil interaction during sepsis and establish neutrophil Cxcr4 activation as a potential means to promote disease tolerance during sepsis.

Nexus of urinary tract infection prevalence of the causal organism and predisposing factors in Kanyakine Hospital, Meru, Kenya

Background: Globally, urinary tract infection (UTI) is most common during pregnancy, prevalence and incidences being higher than in non-pregnant and elderly women. Inadequate data and information deter UTI prevention and management.Methods: The study targeted UTI positive gravid women seeking antenatal services at Kanyakine hospital. The study assessed history of UTI, lifestyle and hygiene factors. Laboratory test and analysis were conducted on urine specimen collected from 135 randomly sampled study subjects. A semi-structured questionnaire was administered to the sampled subjects and their urine tested to detect presence of microorganisms. The results were analysed using established quantitative methods.Results: Most (47%) of the respondents were Escherichia coli infected while Staphylococcus aureus was detected in 20%. of respondents. Increased rate of sexual intercourse was linked to detection of Escherichia coli in 47.6%, Klebsiella pneumoniae in 40% and yeast (Candida) in 47.4%. Wearing non-cotton undergarment was attributed to detection of E. coli in 68.3%, yeast (63.2%) and Klebsiella pneumoniae (60%) of the respondents. Reduced frequency of changing undergarment led to detection of high pathogen levels. The mode of wiping and type of toilet significantly influenced infection (p˂0.05).Conclusions: Hygiene factors that increases chances of E. coli infection remains among the most significant cause of UTI in gravid mothers. This study recommends integration of an elaborate awareness creation on UTI prevention measures at the early stages of pregnancy and further studies to determine the national UTI burden to device mitigation strategies.

Enhancers of Host Immune Tolerance to Bacterial Infection Discovered Using Linked Computational and Experimental Approaches (Adv. Sci. 26/2022)

Drug Repurposing Linked computational and experimental approaches identified that Xenopus laevis embryos can naturally tolerate certain bacteria by modulating their metal ion binding and hypoxia gene networks to maintain health despite high pathogen load. In article number 2200222, using natural tolerance mechanisms as inspiration, Megan Sperry, Richard Novak, Donald E. Ingber, and co-workers induce an artificial tolerant state in susceptible Xenopus using drug repurposing.

Total RNA sequencing of Phlebotomus chinensis sandflies in China revealed viral, bacterial, and eukaryotic microbes potentially pathogenic to humans

ABSTRACT Phlebotomus chinensis sandfly is a neglected insect vector in China that is well-known for carrying Leishmania. Recent studies have expanded its pathogen repertoire with two novel arthropod-borne phleboviruses capable of infecting humans and animals. Despite these discoveries, our knowledge of the general pathogen diversity and overall microbiome composition of this vector species is still very limited. Here we carried out a meta-transcriptomics analysis that revealed the actively replicating/transcribing RNA viruses, DNA viruses, bacteria, and eukaryotic microbes, namely, the “total microbiome”, of several sandfly populations in China. Strikingly, “microbiome” made up 1.8% of total non-ribosomal RNA and comprised more than 87 species, among which 70 were novel, including divergent members of the genera Flavivirus and of the family Trypanosomatidae. Importantly, among these microbes we were able to reveal four distinguished types of human and/or mammalian pathogens, including two phleboviruses (hedi and wuxiang viruses), one novel Spotted fever group rickettsia, as well as a member of Leishmania donovani complex, among which hedi virus and Leishmania each had > 50% pool prevalence rate and relatively high abundance levels. Our study also showed the ubiquitous presence of an endosymbiont, namely Wolbachia, although no anti-viral or anti-pathogen effects were detected based on our data. In summary, our results uncovered the much un-explored diversity of microbes harboured by sandflies in China and demonstrated that high pathogen diversity and abundance are currently present in multiple populations, implying disease potential for exposed local human population or domestic animals.

Two-component regulatory systems in Helicobacter pylori and Campylobacter jejuni: Attractive targets for novel antibacterial drugs.

Two-component regulatory systems (TCRS) are ubiquitous signal transduction mechanisms evolved by bacteria for sensing and adapting to the constant changes that occur in their environment. Typically consisting of two types of proteins, a membrane sensor kinase and an effector cytosolic response regulator, the TCRS modulate via transcriptional regulation a plethora of key physiological processes, thereby becoming essential for bacterial viability and/or pathogenicity and making them attractive targets for novel antibacterial drugs. Some members of the phylum Campylobacterota (formerly Epsilonproteobacteria), including Helicobacter pylori and Campylobacter jejuni, have been classified by WHO as “high priority pathogens” for research and development of new antimicrobials due to the rapid emergence and dissemination of resistance mechanisms against first-line antibiotics and the alarming increase of multidrug-resistant strains worldwide. Notably, these clinically relevant pathogens express a variety of TCRS and orphan response regulators, sometimes unique among its phylum, that control transcription, translation, energy metabolism and redox homeostasis, as well as the expression of relevant enzymes and virulence factors. In the present mini-review, we describe the signalling mechanisms and functional diversity of TCRS in H. pylori and C. jejuni, and provide an overview of the most recent findings in the use of these microbial molecules as potential novel therapeutic targets for the development of new antibiotics.

Genomic features of mecA-positive methicillin-resistant Mammaliicoccus sciuri causing fatal infections in pets admitted to a veterinary intensive care unit

Methicillin-resistant staphylococci have become leading cause of infectious diseases in humans and animals, being categorized as high priority pathogens by the World Health Organization. Although methicillin-resistant Staphylococcus sciuri (recently moved to Mammaliicoccus sciuri) has been widely reported in companion animals, there is scarce information regarding their clinical impact and genomic features. Herein, we reported the occurrence and genomic characteristics of methicillin-resistant M. sciuri recovered from fatal infections in pets admitted to an intensive care unit of a veterinary hospital, in Brazil. Two M. sciuri strains were isolated from bronchoalveolar lavage samples collected from dog (strain SS01) and cat (strain SS02) presenting with sepsis and acute respiratory distress syndrome. Both isolates displayed a multidrug-resistant profile, whereas whole-genome sequencing analysis confirmed the presence of the mecA gene, along to genetic determinant conferring resistance to macrolides, streptogramins, aminoglycosides, and trimethoprim. For both strains, the mec and crr gene complex shared high identity (≥97%) with analogue sequences from a M. sciuri isolated from a human wound infection, in the Czech Republic. Strains were assigned to the sequence type ST52 and the novel ST74. Phylogenomic analysis revealed a broad host range association of these strains with several hosts and sources, including humans, animals, food, and the environment through different years and geographic locations. Our findings demonstrate that infections caused by mecA-positive M. sciuri strains can be a serious threat for veterinary intensive care patients and the medical staff, with additional implications for One Health approaches.

Effect of formic acid treatment on colostrum quality, and on absorption and function of immunoglobulins: a randomized controlled trial in Holstein dairy calves

BackgroundGood quality colostrum is characterized by high immunoglobulin concentration and low pathogen load. Some methods of pathogen reduction can decrease immunoglobulin concentration and potentially affect their function. Objectives were to determine the effect of formic acid treatment on colostral bacterial and immunoglobulin (IgG) levels before feeding, and serum immunoglobulin concentration and neutralizing capabilities after feeding. Fifteen female Holstein calf pairs born < 12 h apart from different dams were randomly assigned to receive four liters of either untreated pooled (both dams) colostrum (MC) or colostrum acidified to pH 4.0–4.5 (AC). Colostrum characteristics estimated; pH, bacterial load, IgG concentration, and neutralization of Infectious Bovine Rhinotracheitis (IBRV/BoHV-1), Bovine Viral Diarrhea (BVDV) Types 1 and 2. Blood samples were collected on days 1, 3 and monthly for 6 months and were analyzed for IgG, and both viral plus leptospiral neutralization, and total protein (day 3 only).ResultsCompared to MC (mean 6.7, SD 0.4; median 6.8, range 6.0–7.3), AC pH was significantly reduced (mean 4.3, SD 0.2; median 4.3, range 4.0–4.5; P < 0.001). Total coliform count (cfu/mL) was also reduced (MC mean 149, SD 444; median 1, range 0–1,700; AC mean 8, SD 31; median 0, range 0–120; P = 0.02). Colostrum IgG concentration was not significantly different between MC (mean 93.3, SD 39.7; median 92.8, range 36.7–164.4 g/L) and AC (mean 101.9, SD 36.7; median 108.3, range 33.8–164.4 g/L; P = 0.54). In calves, serum IgG peaked on day 3 (MC mean 26.1, SD 34.9; median 169.2, range 8.3–151.0 g/L; AC mean 30.2, SD 48.7; median 188.8, range 3.1–204.4 g/L; P = 0.77), and apparent efficiency of IgG absorption was not different between groups (MC mean 24.3, SD 11.4, median 25.3, range 8.6–51.3%; AC mean 22.6, SD 21.7, median 21.6, range 4.1–58.9%; P = 0.65). Thereafter, IgG levels declined but did not differ between groups. MC and AC serum neutralizing titers for IBRV, BVDV Types 1 and 2, or Leptospira interrogans serovars Canicola, and Pomona and L. borgpetersenii serovar Hardjo were not different.ConclusionsColostrum acidification significantly decreased bacterial load fed to newborn calves without affecting colostral IgG concentration or virus neutralization. In addition, acid treatment did not affect serum IgG concentration in calves or its activity against common pathogens.

Development of a Process for Domestic Wastewater Treatment Using Moringa oleifera for Pathogens and Antibiotic-Resistant Bacteria Inhibition under Tropical Conditions

Developing countries are confronted with general issues of municipal wastewater management and treatment. Untreated wastewater and faecal sludge from septic tanks and traditional toilets are often discharged into rivers and used for urban agriculture without any treatment to minimize potential biorisks. Such practices result in potential environmental and public health risks. In this study, a wastewater treatment plant prototype coupled with Moringa oleifera seeds treatment was developed to evaluate their effectiveness for the reduction of faecal indicator bacteria and antibiotic-resistant bacteria in domestic wastewater. We demonstrated that that the proposed wastewater treatment plant prototype reduces bacteria by 99.34%. A high removal of the bacteria load was obtained after the addition of Moringa oleifera seeds into waters, with removal rates of 36.6–78.8% for E. coli, 28.3–84.6% for faecal coliform, 35.3–95.6% for Vibrio cholera and 32.1–92.4% for total flora. A similar effect of Moringa oleifera seeds was noted for the removal of antibiotic-resistant bacteria, extended-spectrum beta-lactamases and carbapenem-resistant Enterobacteriaceae, with a removal rate of up to 98% for E. coli and faecal coliform, 100% for Vibrio cholera and 91.96% for total flora. This study demonstrated the high removal efficiency pathogens and antibiotic-resistant bacteria from domestic wastewater using Moringa oleifera seeds.

Past, present and future distribution of the yellow fever mosquito Aedes aegypti: The European paradox

The global distribution of the yellow fever mosquito Aedes aegypti is the subject of considerable attention because of its pivotal role as a biological vector of several high profile disease pathogens including dengue, chikungunya, yellow fever, and Zika viruses. There is also a lot of interest in the projected future species' distribution. However, less effort has been focused on its historical distribution, which has changed substantially over the past 100 years, especially in southern Europe where it was once widespread, but largely disappeared by the middle of the 20th century.The present work utilises all available historical records of the distribution of Ae. aegypti in southern Europe, the Near East within the Mediterranean Basin and North Africa from the late 19th century until the 1960's to construct a spatial distribution model using matching historical climatic and demographic data.The resulting model was then implemented using current climate and demographic data to assess the potential distribution of the vector in the present. The models were rerun with several different assumptions about the thresholds that determine habitat suitability for Ae. aegypti. The historical model matches the historical distributions well. When it is run with current climate values, the predicted present day distribution is somewhat broader than it used to be particularly in north-west France, North Africa and Turkey. Though it is beginning to reappear in the eastern Caucasus, this ‘potential’ distribution clearly does not match the actual distribution of the species, which suggests some other factors are responsible for its absence. Future distributions based on the historical model also do not match future distributions derived from models based only on present day vector distributions, which predict little or no presence in the Mediterranean Region. At the same time, the vector is widespread in the USA which is predicted to consolidate its range there in future. This contradiction and the implication for possible re-invasion of Europe are discussed.

Design, dynamic docking, synthesis, and in vitro validation of a novel DNA gyrase B inhibitor

Methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-intermediate-resistant Staphylococcus aureus (VRSA) are among the WHO's high priority pathogens. Among these two, MRSA is the most globally documented pathogen that necessitates the pressing demand for new classes of anti-MRSA drugs. Bacterial gyrase targeted therapeutics are unique strategies to overcome cross-resistance as they are present only in bacteria and absent in higher eukaryotes. The GyrB subunit is essential for the catalytic functions of the bacterial enzyme DNA Gyrase, thereby constituting a promising druggable target. The current study performed a structure-based virtual screening to designing GyrB target-specific candidate molecules. The de novo ligand design of novel hit molecules was performed using a rhodanine scaffold. Through a systematic in silico screening process, the hit molecules were screened for their synthetic accessibility, drug-likeness and pharmacokinetics properties in addition to its target specific interactions. Of the 374 hit molecules obtained through de novo ligand design, qsl-304 emerged as the most promising ligand. The molecular dynamic simulation studies confirmed the stable interaction between the key residues and qsl-304. qsl-304 was synthesized through a one-step chemical synthesis procedure, and the in vitro activity was proven, with an IC50 of 31.23 µg/mL against the novobiocin resistant clinical isolate, Staphylococcus aureus sa-P2003. Further studies on time-kill kinetics showed the bacteriostatic nature with the diminished recurrence of resistance. The on-target gyrB inhibition further proved the efficacy of qsl-304. Communicated by Ramaswamy H. Sarma

Elucidating Mechanisms of Tolerance to Salmonella Typhimurium across Long-Term Infections Using the Collaborative Cross.

ABSTRACTUnderstanding the molecular mechanisms underlying resistance and tolerance to pathogen infection may present the opportunity to develop novel interventions. Resistance is the absence of clinical disease with a low pathogen burden, while tolerance is minimal clinical disease with a high pathogen burden. Salmonella is a worldwide health concern. We studied 18 strains of collaborative cross mice that survive acute Salmonella Typhimurium (STm) infections. We infected these strains orally and monitored them for 3 weeks. Five strains cleared STm (resistant), six strains maintained a bacterial load and survived (tolerant), while seven strains survived >7 days but succumbed to infection within the study period and were called “delayed susceptible.” Tolerant strains were colonized in the Peyer’s patches, mesenteric lymph node, spleen, and liver, while resistant strains had significantly reduced bacterial colonization. Tolerant strains had lower preinfection core body temperatures and had disrupted circadian patterns of body temperature postinfection sooner than other strains. Tolerant strains had higher circulating total white blood cells than resistant strains, driven by increased numbers of neutrophils. Tolerant strains had more severe tissue damage and higher circulating levels of monocyte chemoattractant protein 1 (MCP-1) and interferon gamma (IFN-γ), but lower levels of epithelial neutrophil-activating protein 78 (ENA-78) than resistant strains. Quantitative trait locus (QTL) analysis revealed one significant association and six suggestive associations. Gene expression analysis identified 22 genes that are differentially regulated in tolerant versus resistant animals that overlapped these QTLs. Fibrinogen genes (Fga, Fgb, and Fgg) were found across the QTL, RNA, and top canonical pathways, making them the best candidate genes for differentiating tolerance and resistance.