Disentangling the formation, mechanism, and evolvement of the covalent methanesulfonyl fluoride acetylcholinesterase adduct: Insights into an aged-like inactive complex susceptible to reactivation by a combination of nucleophiles

Chemical warfare nerve agents and pesticides, known as organophosphorus compounds inactivate cholinesterases (ChEs) by phosphorylating the serine hydroxyl group located at the active site of ChEs. Over the course of time, phosphorylation is followed by loss of an organophosphate-leaving group and the bond with ChEs becomes irreversible, a process known as aging. Differently, structurally related irreversible catalytic poisons bearing sulfur instead of phosphorus convert ChEs in its aged form only by covalently binding to the key catalytic serine. Kinetic and crystallographic studies of the interaction between Torpedo californica acetylcholinesterase (TcAChE) and a small organosulfonate, methanesulfonyl fluoride (MSF), indeed revealed irreversibly methylsulfonylated serine 200, to be isosteric with the bound aged sarin/soman analogues. The potent bulky reversible inhibitor 7-bis-tacrine (BTA) adopts, in the active site of the crystal structure of the MSF-enzyme adduct, a location and an orientation that closely resemble the one being found in the crystal structure of the BTA-enzyme complex. Remarkably, the presence of BTA accelerates the rate of methanesulfonylation by a factor of two. This unexpected result can be explained on the basis of two facts: i) the steric hindrance exerted by BTA to MSF in accessing the active site and ii) the acceleration of the MSF-enzyme adduct formation as a consequence of the lowering of the rotational and translational degrees of freedom in the proximity of the catalytic serine. It is well known that pralidoxime (2-Pyridine Aldoxime Methyl chloride, 2-PAM) alone or in the presence of the substrate acetylcholine cannot reactivate the active site serine of the TcAChE-MSF adduct. We show that the simultaneous presence of 2-PAM and the additional neutral oxime, 2-[(hydroxyimino)methyl]-l-methylimidazol (2-HAM), triggers the reactivation process of TcAChE within the hour timescale. Overall, our results pave the way toward the likely use of a cocktail of distinctive oximes as a promising recipe for an effective and fast reactivation of aged cholinesterases.

Evaluation of Icotinib as a Potent and Selective Inhibitor of Aldehyde Oxidase for Reaction Phenotyping in Human Hepatocytes

Aldehyde oxidase (AO) is a molybdenum cofactor-containing cytosolic enzyme that has gained prominence due to its involvement in the developmental failure of several drug candidates in first-in-human trials. Unlike cytochrome P450s (P450) and glucuronosyltransferase, AO substrates have been plagued by poor in vitro to in vivo extrapolation, leading to low systemic exposures and underprediction of human dose. However, apart from measuring a drug's AO clearance rates, it is also important to determine the relative contribution to metabolism by this enzyme (fm,AO). Although hydralazine is the most well-studied time-dependent inhibitor (TDI) of AO and is frequently employed for AO reaction phenotyping in human hepatocytes to derive fm,AO, multiple studies have expressed concerns pertaining to its utility in providing accurate estimates of fm,AO values due to its propensity to significantly inhibit P450s at the concentrations typically utilized for reaction phenotyping. In this study, we characterized icotinib, a cyclized analogue of erlotinib, as a potent TDI of AO - inactivating human liver cytosolic zoniporide 2-oxidation equipotently with erlotinib with a k inact/K I ratio of 463 and 501 min-1mM-1 , respectively. Moreover, icotinib also exhibits selectivity against P450 and elicits significantly weaker inhibition against human liver microsomal UGT1A1/3 as compared to erlotinib. Finally, we evaluated icotinib as an inhibitor of AO for reaction phenotyping in cryopreserved human hepatocytes and demonstrated that it can yield more accurate prediction of fm,AO compared to hydralazine and induce sustained suppression of AO activity at higher cell densities - which will be important for reaction phenotyping endeavors of low clearance drugs. Significance Statement In this study, we characterized icotinib as a potent time-dependent inhibitor of AO with ample selectivity margins against the P450s and UGT1A1/3 and demonstrated its utility for reaction phenotyping in human hepatocytes to obtain accurate estimates of fm,AO for victim DDI risk predictions. We envisage the adoption of icotinib in place of hydralazine in AO reaction phenotyping.

A binding site for phosphoinositides described by multiscale simulations explains their modulation of voltage-gated sodium channels

Voltage-gated sodium channels (Naᵥ) are membrane proteins which open to facilitate the inward flux of sodium ions into excitable cells. In response to stimuli, Naᵥ channels transition from the resting, closed state to an open, conductive state, before rapidly inactivating. Dysregulation of this functional cycle due to mutations causes diseases including epilepsy, pain conditions, and cardiac disorders, making Naᵥ channels a significant pharmacological target. Phosphoinositides are important lipid cofactors for ion channel function. The phosphoinositide PI(4,5)P2 decreases Naᵥ1.4 activity by increasing the difficulty of channel opening, accelerating fast inactivation and slowing recovery from fast inactivation. Using multiscale molecular dynamics simulations, we show that PI(4,5)P2 binds stably to inactivated Naᵥ at a conserved site within the DIV S4-S5 linker, which couples the voltage-sensing domain (VSD) to the pore. As the Naᵥ C-terminal domain is proposed to also bind here during recovery from inactivation, we hypothesize that PI(4,5)P2 prolongs inactivation by competitively binding to this site. In atomistic simulations, PI(4,5)P2 reduces the mobility of both the DIV S4-S5 linker and the DIII-IV linker, responsible for fast inactivation, slowing the conformational changes required for the channel to recover to the resting state. We further show that in a resting state Naᵥ model, phosphoinositides bind to VSD gating charges, which may anchor them and impede VSD activation. Our results provide a mechanism by which phosphoinositides alter the voltage dependence of activation and the rate of recovery from inactivation, an important step for the development of novel therapies to treat Naᵥ-related diseases.

Inactivation of highly transmissible livestock and avian viruses including influenza A and Newcastle disease virus for molecular diagnostics

There is a critical need for an inactivation method that completely inactivates pathogens at the time of sample collection while maintaining the nucleic acid quality required for diagnostic PCR testing. This inactivation method is required to alleviate concerns about transmission potential, minimize shipping complications and cost, and enable testing in lower containment laboratories, thereby enhancing disease diagnostics through improved turn-around time. This study evaluated a panel of 10 surrogate viruses that represent highly pathogenic animal diseases. These results showed that a commercial PrimeStore® molecular transport media (PSMTM) completely inactivated all viruses tested by >99.99%, as determined by infectivity and serial passage assays. However, the detection of viral nucleic acid by qRT-PCR was comparable in PSMTM and control-treated conditions. These results were consistent when viruses were evaluated in the presence of biological material such as sera and cloacal swabs to mimic diagnostic sample conditions for non-avian and avian viruses, respectively. The results of this study may be utilized by diagnostic testing laboratories for highly pathogenic agents affecting animal and human populations. These results may be used to revise guidance for select agent diagnostic testing and the shipment of infectious substances.

Bactericidal efficacy of plasma-activated water against Vibrio parahaemolyticus on Litopenaeus vannamei

In this study, the antimicrobial mechanism of plasma-activated water (PAW) against Vibrio parahaemolyticus and the effectiveness of PAW in artificially contaminated Litopenaeus vannamei were investigated. The results demonstrated a significant reduction (p < 0.05) in viable counts of V. parahaemolyticus with increasing plasma discharge time (5, 10, 20, and 30 min) and PAW immersion time (3, 5, 10, 20, and 30 s). Specifically, the count of V. parahaemolyticus decreased by 2.1, 2.7, 3.3, and 4.4 log CFU/mL after exposed to PAW 5, PAW 10, PAW 20, and PAW 30 for 30 s, respectively. Significant cell surface wrinkling, accompanied by notable nucleic acid and protein leakage were observed after treatment with PAW. The permeability of the inner and outer cell membranes was significantly increased (p < 0.05), along with an increase in electrical conductivity (p < 0.05). The reactive oxygen species (ROS) within V. parahaemolyticus cells were significantly increased (p < 0.05), while superoxide dismutase (SOD) activity, and the relative expression of the ompW, emrD, and luxS genes were significantly decreased (p < 0.05). A reduction number of 1.3, 1.8, 2.1, and 2.2 log CFU/g of V. parahaemolyticus in artificially contaminated L. vannamei was obtained with PAW for 5 min. The study elucidated that PAW could destroy cell membranes, leading to cell death. The findings would strengthen strategies for V. parahaemolyticus control and provide a potential application of PAW for preserving aquatic products.

Dissociable neuronal substrates of visual feature attention and working memory

Attention and working memory (WM) are distinct cognitive functions, yet given their close interactions, it is often assumed that they share the same neuronal mechanisms. We show that in macaques performing a WM-guided feature attention task, the activity of most neurons in areas middle temporal (MT), medial superior temporal (MST), lateral intraparietal (LIP), and posterior lateral prefrontal cortex (LPFC-p) displays attentional modulation or WM coding and not both. One area thought to play a role in both functions is LPFC-p. To test this, we optogenetically inactivated LPFC-p bilaterally during different task periods. Attention period inactivation reduced attentional modulation in LPFC-p, MST, and LIP neurons and impaired task performance. In contrast, WM period inactivation did not affect attentional modulation or performance and minimally affected WM coding. Our results suggest that feature attention and WM have dissociable neuronal substrates and that LPFC-p plays a critical role in feature attention, but not in WM.

The Anterior Thalamus Preferentially Drives Allocentric But Not Egocentric Orientation Tuning in Postrhinal Cortex

Navigating a complex world requires integration of multiple spatial reference frames, including information about one's orientation in both allocentric and egocentric coordinates. Combining these two information sources can provide additional information about one's spatial location. Previous studies have demonstrated that both egocentric and allocentric spatial signals are reflected by the firing of neurons in the rat postrhinal cortex (POR), an area that may serve as a hub for integrating allocentric head direction (HD) cell information with egocentric information from center-bearing and center-distance cells. However, we have also demonstrated that POR HD cells are uniquely influenced by the visual properties and locations of visual landmarks, bringing into question whether the POR HD signal is truly allocentric as opposed to simply being a response to visual stimuli. To investigate this issue, we recorded HD cells from the POR of female rats while bilaterally inactivating the anterior thalamus (ATN), a region critical for expression of the "classic" HD signal in cortical areas. We found that ATN inactivation led to a significant decrease in both firing rate and tuning strength for POR HD cells, as well as a disruption in the encoding of allocentric location by conjunctive HD/egocentric cells. In contrast, POR egocentric cells without HD tuning were largely unaffected in a consistent manner by ATN inactivation. These results indicate that the POR HD signal originates at least partially from projections from the ATN and supports the view that the POR acts as a hub for the integration of egocentric and allocentric spatial representations.

SARS-CoV-2 inactivation in laboratory animal tissues with 4% formaldehyde or 5% glutaraldehyde for transfer to biosafety level 1 laboratories

The SARS-CoV-2 pandemic required the immediate need to transfer inactivated tissue from biosafety level (BSL)-3 to BSL-1 areas to enable downstream analytical methods. No validated SARS-CoV-2 inactivation protocols were available for either formaldehyde (FA)-fixed or glutaraldehyde (GA)-fixed tissues. Therefore, representative tissue from ferrets and hamsters was spiked with 2.2 × 106 tissue culture infectious dose 50% per ml (TCID50/ml) SARS-CoV-2 or were obtained from mice experimentally infected with SARS-CoV-2. SARS-CoV-2 inactivation was demonstrated with 4% FA or 5% GA at room temperature for 72 hours by a titer reduction of up to 103.8 TCID50/ml in different animal tissues with a maximum protein content of 100 µg/mg and a thickness of up to 10 mm for FA and 8 mm for GA. Our protocols can be easily adapted for validating the inactivation of other pathogens to allow for the transfer of biological samples from BSL-3 areas to BSL-1 laboratories.

X-ray irradiation effectively inactivated lymphocytes in transfusion in vivo monitored by the bioluminescence transfusion-associated graft-versus-host disease model

BACKGROUND AND OBJECTIVES

Transfusion of cold-stored whole blood is the preferred resuscitation method for trauma patients but may cause transfusion-associated graft-versus-host disease (TA-GVHD). Standard clinical practice to prevent this is to irradiate blood components with gamma-rays. X-ray irradiations are also a safe and effective alternative to gamma-ray irradiation. We established a visual mouse model of TA-GVHD to compare the viability and function of lymphocytes exposed to gamma- and x-ray irradiation.

MATERIALS AND METHODS

A haploidentical transplantation mouse model was established to simulate TA-GVHD with Balb/c mice as donors and hybrid F1 CB6 mice (Balb/c × C57) as recipients. Spleen cells from Tg-Fluc+ Balb/c mice were isolated and irradiated with gamma-rays and x-rays. Lymphocyte activation, apoptosis and proliferation post phorbol 1 2-myristate 1 3-acetate (PMA) stimulation were evaluated. After transfusion, we monitored Fluc+ lymphocytes daily by bioluminescence imaging. Recipients were euthanized on day 21, and tissues were examined pathologically and for inflammatory cytokines.

RESULTS

The viability of gamma- or x-ray irradiated lymphocytes decreased significantly with slight changes in proliferation in vivo after transfusion. Compared with the non-irradiated group, both the gamma- and x-ray irradiated groups showed significantly decreased clinical scoring and inflammatory cytokine levels. The fluorescence intensity of the body and target organs was reduced after irradiation.

CONCLUSION

No recipients acquired TA-GVHD after lymphocyte transfusion subjected to gamma- or x-rays, showing that x-rays inactivate as well as gamma rays and are suitable for irradiating whole blood.

Selective Recovery of Cathode Materials from Spent Lithium-Ion Battery Material with a Near-Room-Temperature Separation

Effective separation of cathode materials from the current collector is a critical step in recycling a spent lithium-ion battery (LIB). This typically necessitates the decomposition or dissolution of the organic binder, poly(vinylidene fluoride) (PVDF), to achieve efficient recovery of cathode materials. However, this process requires a high decomposition temperature, typically between 400 and 600 °C, and can lead to side reactions, such as current collector oxidation/brittleness, decomposition of cathode materials, and formation of metal fluorides. In this study, we propose that non-thermal plasma (NTP) treatment can be used to achieve an extremely high separation of cathode materials and aluminum current collector at near room temperature. Instead of relying on PVDF decomposition, which requires high temperatures, PVDF can be deactivated by partially breaking down long molecular chains with appropriate NTP conditions. With a total treatment time of around 2000 s and an environmental temperature of approximately 80 °C, minor side reactions can be avoided. The separation rate can reach up to 95.69%, and high-quality cathode materials can be obtained with only 0.02 wt % aluminum impurity content. This research could potentially offer a new approach toward minimizing recycling steps and reducing energy consumption in the recycling of spent LIBs. It could also be extended to the recovery of a broader range of electronic wastes.

Evaluation of Foot-and-Mouth Disease (FMD) Virus Asia1 Genotype-V as an FMD Vaccine Candidate: Study on Vaccine Antigen Production Yield and Inactivation Kinetics

South Korea has experienced outbreaks of foot-and-mouth disease (FMD) of serotypes O and A, leading to nationwide vaccination with a bivalent vaccine. Since the FMD virus (FMDV) Asia1 group-V genotype occurred in North Korea in 2007, an Asia1/MOG/05 vaccine strain belonging to the Asia1 group-V genotype was developed using a genetic recombination method (Asia1/MOG/05-R). This study aimed to evaluate the antigen productivity and viral inactivation kinetics of Asia1/MOG/05-R to assess its commercial viability. The antigen yield of Asia1/MOG/05-R produced in flasks and bioreactors was approximately 4.0 μg/mL. Binary ethylenimine (BEI) inactivation kinetics of Asia1/MOG/05-R showed that 2 mM and 1.0 mM BEI treatment at 26 °C and 37 °C, respectively, resulted in a virus titer <10-7 TCID50/mL within 24 h, meeting the inactivation kinetics criteria. During incubation at 26 °C and 37 °C, 10% antigen loss occurred, but not due to BEI treatment. When pigs were inoculated twice with the Asia1/MOG/05-R antigen, the virus neutralization titer increased to approximately 1:1000; therefore, it can sufficiently protect against Asia1/MOG/05-R and Asia1 Shamir viruses. The Asia1/MOG/05-R will be useful as a vaccine strain for domestic antigen banks.

Evaluation of Inactivation Methods for Rift Valley Fever Virus in Mouse Microglia

Rift Valley fever phlebovirus (RVFV) is a highly pathogenic mosquito-borne virus with bioweapon potential due to its ability to be spread by aerosol transmission. Neurological symptoms are among the worst outcomes of infection, and understanding of pathogenesis mechanisms within the brain is limited. RVFV is classified as an overlap select agent by the CDC and USDA; therefore, experiments involving fully virulent strains of virus are tightly regulated. Here, we present two methods for inactivation of live virus within samples derived from mouse microglia cells using commercially available kits for the preparation of cells for flow cytometry and RNA extraction. Using the flow cytometry protocol, we demonstrate key differences in the response of primary murine microglia to infection with fully virulent versus attenuated RVFV.

Comprehensive Assessment of Inactivation Methods for Madariaga Virus

The Eastern Equine Encephalitis Virus (EEEV) is an emerging public health threat, with the number of reported cases in the US increasing in recent years. EEEV is a BSL3 pathogen, and the North American strain is a US Federal Select Agent (SA). These restrictions make experiments with EEEV difficult to perform, as high-tech equipment is often unavailable in BSL3 spaces and due to concerns about generating aerosols during manipulations. Therefore, a range of inactivation methods suitable for different downstream analysis methods are essential for advancing research on EEEV. We used heat, chemical, and ultraviolet (UV)-based methods for the inactivation of infected cells and supernatants infected with the non-select agent Madariaga virus (MADV). Although the MADV and EEEV strains are genetically distinct, differing by 8-11% at the amino acid level, they are expected to be similarly susceptible to various inactivation methods. We determined the following to be effective methods of inactivation: heat, TRIzol LS, 4% PFA, 10% formalin, and UV radiation for infected supernatants; TRIzol, 2.5% SDS with BME, 0.2% NP40, 4% PFA, and 10% formalin for infected cells. Our results have the potential to expand the types and complexity of experiments and analyses performed by EEEV researchers.

Inactivation of antibiotic-resistant bacteria Escherichia coli by electroporation

Introduction

In modern times, bacterial infections have become a growing problem in the medical community due to the emergence of antibiotic-resistant bacteria. In fact, the overuse and improper disposal of antibiotics have led to bacterial resistance and the presence of such bacteria in wastewater. Therefore, it is critical to develop effective strategies for dealing with antibiotic-resistant bacteria in wastewater. Electroporation has been found to be one of the most promising complementary techniques for bacterial inactivation because it is effective against a wide range of bacteria, is non-chemical and is highly optimizable. Many studies have demonstrated electroporation-assisted inactivation of bacteria, but rarely have clinical antibiotics or bacteria resistant to these antibiotics been used in the study. Therefore, the motivation for our study was to use a treatment regimen that combines antibiotics and electroporation to inactivate antibiotic-resistant bacteria.

Methods

We separately combined two antibiotics (tetracycline and chloramphenicol) to which the bacteria are resistant (with a different resistance mode) and electric pulses. We used three different concentrations of antibiotics (40, 80 and 150 µg/ml for tetracycline and 100, 500 and 2000 µg/ml for chloramphenicol, respectively) and four different electric field strengths (5, 10, 15 and 20 kV/cm) for electroporation.

Results and discussion

Our results show that electroporation effectively enhances the effect of antibiotics and inactivates antibiotic-resistant bacteria. The inactivation rate for tetracycline or chloramphenicol was found to be different and to increase with the strength of the pulsed electric field and/or the concentration of the antibiotic. In addition, we show that electroporation has a longer lasting effect (up to 24 hours), making bacteria vulnerable for a considerable time. The present work provides new insights into the use of electroporation to inactivate antibiotic-resistant bacteria in the aquatic environment.

Evaluation of Stability, Inactivation, and Disinfection Effectiveness of Mpox Virus

BACKGROUND

Mpox virus (MPXV) infections have increased in many countries since May 2022, increasing demand for diagnostic tests and research on the virus. To ensure personnel safety, appropriate and reliable measures are needed to disinfect and inactivate infectious samples; Methods: We evaluated the stability of infectious MPXV cultures stored at different temperatures and through freeze-thaw cycles. Heat physical treatment (56 °C, 70 °C, 95 °C), chemical treatment (beta-propiolactone (BPL)) and two commercialized disinfectants (Micro-Chem Plus (MCP) and ethanol) were tested against infectious MPXV cultures; Results: The results indicated that MPXV stability increases with lower temperatures. The MPXV titer was stable within three freeze-thaw cycles and only decreased by 1.04 log10 (lg) 50% cell culture infective dose (CCID50) per milliliter (12.44%) after twelve cycles. MPXV could be effectively inactivated at 56 °C for 40 min, 70 °C for 10 min, and 95 °C for 5 min. For BPL inactivation, a 1:1000 volume ratio (BPL:virus) could also effectively inactivate MPXV. A total of 2% or 5% MCP and 75% ethanol treated with MPXV for at least 1 min could reduce >4.25 lg; Conclusions: MPXV shows high stability to temperature and freeze-thaw. Heat and BPL treatments are effective for the inactivation of MPXV, while MCP and ethanol are effective for disinfection, which could help laboratory staff operate the MPXV under safer conditions and improve operational protocols.

UV-C Light Intervention as a Barrier against Airborne Transmission of SARS-CoV-2

BACKGROUND

SARS-CoV-2 continues to impact human health globally, with airborne transmission being a significant mode of transmission. In addition to tools like vaccination and testing, countermeasures that reduce viral spread in indoor settings are critical. This study aims to assess the efficacy of UV-C light, utilizing the Violett sterilization device, as a countermeasure against airborne transmission of SARS-CoV-2 in the highly susceptible Golden Syrian hamster model.

METHODS

Two cohorts of naïve hamsters were subjected to airborne transmission from experimentally infected hamsters; one cohort was exposed to air treated with UV-C sterilization, while the other cohort was exposed to untreated air.

RESULTS

Treatment of air with UV-C light prevented the airborne transmission of SARS-CoV-2 from the experimentally exposed hamster to naïve hamsters. Notably, this protection was sustained over a multi-day exposure period during peak viral shedding by hamsters.

CONCLUSIONS

These findings demonstrate the efficacy of the UV-C light to mitigate against airborne SARS-CoV-2 transmission. As variants continue to emerge, UV-C light holds promise as a tool for reducing infections in diverse indoor settings, ranging from healthcare facilities to households. This study reinforces the urgency of implementing innovative methods to reduce airborne disease transmission and safeguard public health against emerging biological threats.

In vitro virucidal activity of a commercial disinfectant against viruses of domestic animals and poultry

Outbreaks of viral diseases in animals are a cause of concern for animal welfare and economics of animal production. One way to disrupt the cycle of infection is by combating viruses in the environment and prohibiting them from being transmitted to a new host. Viral contamination of the environment can be reduced using well-tested and efficacious disinfectants. Duplalim is a commercially available disinfectant consisting of 12% glutaraldehyde and 10% quaternary ammonium compounds. We evaluated this disinfectant for its efficacy against several viruses in poultry (n = 3), pigs (n = 5), dogs (n = 2), and cattle (n = 4). In suspension tests, 1:100 dilution of Duplalim was found to inactivate more than 99% of these 14 viruses in 15 min or less. The titers of a majority of these viruses decreased by ≥99.99% in <60 min of contact time. In conclusion, the ingredient combination in Duplalim is very effective in inactivating common viruses of domestic animals and poultry.

A facile approach for incorporating tyrosine esters to probe ion-binding sites and backbone hydrogen bonds

Amide-to-ester substitutions are used to study the role of the amide bonds of the protein backbone in protein structure, function, and folding. An amber suppressor tRNA/synthetase pair has been reported for incorporation of p-hydroxy-phenyl-L-lactic acid (HPLA), thereby introducing ester substitution at tyrosine residues. However, the application of this approach was limited due to the low yields of the modified proteins and the high cost of HPLA. Here we report the in vivo generation of HPLA from the significantly cheaper phenyl-L-lactic acid. We also construct an optimized plasmid with the HPLA suppressor tRNA/synthetase pair that provides higher yields of the modified proteins. The combination of the new plasmid and the in-situ generation of HPLA provides a facile and economical approach for introducing tyrosine ester substitutions. We demonstrate the utility of this approach by introducing tyrosine ester substitutions into the K+ channel KcsA and the integral membrane enzyme GlpG. We introduce the tyrosine ester in the selectivity filter of the M96V mutant of the KcsA to probe the role of the second ion binding site in the conformation of the selectivity filter and the process of inactivation. We use tyrosine ester substitutions in GlpG to perturb backbone H-bonds to investigate the contribution of these H-bonds to membrane protein stability. We anticipate that the approach developed in this study will facilitate further investigations using tyrosine ester substitutions.

Benzalkonium Chloride and Benzethonium Chloride Effectively Reduce Spore Germination of Ginger Soft Rot Pathogens: Fusarium solani and Fusarium oxysporum

Ginger soft rot is a serious soil-borne disease caused by Fusarium solani and Fusarium oxysporum, resulting in reduced crop yields. The application of common chemical fungicides is considered to be an effective method of sterilization, and therefore, they pose a serious threat to the environment and human health due to their high toxicity. Benzalkonium chloride (BAC) and benzethonium chloride (BEC) are two popular quaternary ammonium salts with a wide range of fungicidal effects. In this study, we investigated the fungicidal effects of BAC and BEC on soft rot disease of ginger as alternatives to common chemical fungicides. Two soft rot pathogens of ginger were successfully isolated from diseased ginger by using the spread plate method and sequenced as F. solani and F. oxysporum using the high-throughput fungal sequencing method. We investigated the fungicidal effects of BAC and BEC on F. solani and F. oxysporum, and we explored the antifungal mechanisms. Almost complete inactivation of spores of F. solani and F. oxysporum was observed at 100 mg/L fungicide concentration. Only a small amount of spore regrowth was observed after the inactivation treatment of spores of F. solani and F. oxysporum in soil, which proved that BAC and BEC have the potential to be used as an alternative to common chemical fungicides for soil disinfection of diseased ginger.

An Overview of Diverse Strategies To Inactivate Enterobacteriaceae-Targeting Bacteriophages

Bacteriophages are viruses that infect bacteria and thus threaten industrial processes relying on the production executed by bacterial cells. Industries bear huge economic losses due to such recurring and resilient infections. Depending on the specificity of the process, there is a need for appropriate methods of bacteriophage inactivation, with an emphasis on being inexpensive and high efficiency. In this review, we summarize the reports on antiphagents, i.e., antibacteriophage agents on inactivation of bacteriophages. We focused on bacteriophages targeting the representatives of the Enterobacteriaceae family, as its representative, Escherichia coli, is most commonly used in the bio-industry. The review is divided into sections dealing with bacteriophage inactivation by physical factors, chemical factors, and nanotechnology-based solutions.

The Hodgkin-Huxley-Katz Prize Lecture: A Markov model with permeation-dependent gating that accounts for resurgent current of voltage-gated Na channels

Many neurons that fire high-frequency action potentials express specialized voltage-gated Na channel complexes that not only conduct transient current upon depolarization, but also pass resurgent current upon repolarization. The resurgent current is associated with recovery of transient current, even at moderately negative potentials where fast inactivation is usually absorbing. The combined results of many experimental studies have led to the hypothesis that resurgent current flows upon repolarization when an endogenous blocking protein that occludes open channels at depolarized potentials is expelled by inwardly permeating Na ions. Additional observations have suggested that the position of the voltage sensor of domain IV regulates the affinity of the channel for the putative blocker. To test the effectiveness of a kinetic scheme incorporating these features, here we develop and justify a Markov model with states grounded in known Na channel conformations. Simulations were designed to investigate whether including a permeation-dependent unblocking rate constant and two open-blocked states, superimposed on conformations and voltage-sensitive movements present in all voltage-gated Na channels, is sufficient to account for the unusual gating of channels with a resurgent component. Optimizing rate constant parameters against a wide range of experimental data from cerebellar Purkinje cells demonstrates that a kinetic scheme for Na channels incorporating the novel aspects of a permeation-dependent unblock, as well as distinct high- and low-affinity blocked states, reproduces all the attributes of experimentally recorded Na currents in a physiologically plausible manner.

The dorsal stream of visual processing and action-specific domains in parietal and frontal cortex in primates

This review summarizes our findings obtained from over 15 years of research on parietal-frontal networks involved in the dorsal stream of cortical processing. We have presented considerable evidence for the existence of similar, partially independent, parietal-frontal networks involved in specific motor actions in a number of primates. These networks are formed by connections between action-specific domains representing the same complex movement evoked by electrical microstimulation. Functionally matched domains in the posterior parietal (PPC) and frontal (M1-PMC) motor regions are hierarchically related. M1 seems to be a critical link in these networks, since the outputs of M1 are essential to the evoked behavior, whereas PPC and PMC mediate complex movements mostly via their connections with M1. Thus, lesioning or deactivating M1 domains selectively blocks matching PMC and PPC domains, while having limited impact on other domains. When pairs of domains are stimulated together, domains within the same parietal-frontal network (matching domains) are cooperative in evoking movements, while they are mainly competitive with other domains (mismatched domains) within the same set of cortical areas. We propose that the interaction of different functional domains in each cortical region (as well as in striatum) occurs mainly via mutual suppression. Thus, the domains at each level are in competition with each other for mediating one of several possible behavioral outcomes.

Inactivation Effect of Germination Combined with Cold Plasma Treatment on Bacillus licheniformis Spores

Food spoilage, primarily caused by spore-forming bacteria, has become a critical concern since it results in substantial economic losses within the food industry. Past investigations have successfully identified Bacillus licheniformis as the main bacterium responsible for spoilage in roast chicken. In this study, we screened a new sterilization combination from 16 germinants and 4 cold plasma conditions, respectively. Among them, the combination of "A"GFNa-1 (composed of 60 mmol/L L-alanine, 10 mmol/L D-glucose, 10 mmol/L D-fructose, and 1 g/L NaCl) with cold plasma treatment (packed with 100% argon at 70 kV) proved effective in deactivating B. licheniformis spores, resulting in a reduction of approximately 2.1 log CFU/mL. Furthermore, we exposed the spores to different conditions: CK (no germination, no cold plasma), MF (germination only), CP (no germination, 100% argon packed, 70 kV cold plasma treatment for 3 min), and MF + CP (germination for 5 h, 100% argon packed, 70 kV cold plasma treatment for 3 min). The results of heat inactivation and dipicolinic acid (DPA) release rate demonstrated that cold plasma treatment effectively inactivated both spores and vegetative cells without inducing germination. Additionally, the reduced survival under hyperosmotic conditions and the presence of distinct red fluorescence patterns observed through confocal laser scanning microscopy (CLSM) collectively suggest that cold plasma treatment disrupts the inner membrane structure and leads to the inactivation of B. licheniformis. Overall, our findings indicate a spore clearance rate of 99.2% and suggest that the combination of efficient germinants and cold plasma treatment holds promise as a viable approach to mitigate spore contamination in the food industry.

Observed Kinetics of Enterovirus Inactivation by Free Chlorine Are Host Cell-Dependent

Virucidal efficacies of disinfectants are typically assessed by infectivity assay utilizing a single type of host cell. Enteroviruses infect multiple host cells via various entry routes, and each entry route may be impaired differently by a given disinfectant. Yet, it is unknown how the choice of host cells affects the observed inactivation kinetics. Here, we evaluated the inactivation kinetics of echovirus 11 (E11) by free chlorine, ultraviolet (UV) irradiation, and heat, using three different host cells (BGMK, RD, and A549). Inactivation rates were independent of the host cell for treatment of E11 by UV or heat. Conversely, E11 inactivation by free chlorine occurred 2-fold faster when enumerated on BGMK cells compared with RD and A549 cells. Host cell-dependent inactivation kinetics by free chlorine were also observed for echovirus 7, 9, and 13, and coxsackievirus A9. E11 inactivation by free chlorine was partly caused by a loss in host cell attachment, which was most pronounced for BGMK cells. BGMK cells lack the attachment receptor CD55 and a key subunit of the uncoating receptor β2M, which may contribute to the differential inactivation kinetics for this cell type. Consequently, inactivation kinetics of enteroviruses should be assessed using host cells with different receptor profiles.

Dynamic Thermal Treatments in Green Coconut Water Induce Dynamic Stress Adaptation of Listeria innocua That Increases Its Thermal Resistance

The global coconut water market is projected to grow in the upcoming years, attributed to its numerous health benefits. However, due to its susceptibility to microbial contamination and the limitations of non-thermal decontamination methods, thermal treatments remain the primary approach to ensure the shelf-life stability and the microbiological safety of the product. In this study, the thermal inactivation of Listeria innocua, a Listeria monocytogenes surrogate, was evaluated in coconut water and in tryptone soy broth (TSB) under both isothermal (50-60 °C) and dynamic conditions (from 30 to 60 °C, with temperature increases of 0.5, 1 and 5 °C/min). Mathematical models were used to analyse the inactivation data. The Geeraerd model effectively described the thermal inactivation of L. innocua in both TSB and coconut water under isothermal conditions, with close agreement between experimental data and model fits. Parameter estimates and analysis revealed that acidified TSB is a suitable surrogate medium for studying the thermal inactivation of L. innocua in coconut water, despite minor differences observed in the shoulder length of inactivation curves, likely attributed to the media composition. The models fitted to the data obtained at isothermal conditions fail to predict L. innocua responses under dynamic conditions. This is attributed to the stress acclimation phenomenon that takes place under dynamic conditions, where bacterial cells adapt to initial sub-lethal treatment stages, leading to increased thermal resistance. Fitting the Bigelow model directly to dynamic data with fixed z-values reveals a three-fold increase in D-values with lower heating rates, supporting the role of stress acclimation. The findings of this study aid in designing pasteurization treatments targeting L. innocua in coconut water and enable the establishment of safe, mild heat treatments for refrigerated, high-quality coconut water.

Stability and Inactivation of Monkeypox Virus on Inanimate Surfaces

The spread of nonzoonotic monkeypox virus (MPXV) infections necessitates the reevaluation of hygiene measures. To date, only limited data are available on MPXV surface stability. Here, we evaluate the stability of infectious MPXV on stainless steel stored at different temperatures, while using different interfering substances to mimic environmental contamination. MPXV persistence increased with decreasing temperature. Additionally, we were able to show that MPXV could efficiently be inactivated by alcohol- and aldehyde-based surface disinfectants. These findings underline the stability of MPXV on inanimate surfaces and support the recommendations to use alcohol-based disinfectants as prevention measures or in outbreak situations.

Inactivation of Salmonella Typhimurium and Listeria monocytogenes on buckwheat seeds through combination treatment with plasma, vacuum packaging, and hot water

AIMS

The objectives of this study were to evaluate the effect of combination treatment with cold plasma (CP), vacuum packaging (VP), and hot water (HW) on the inactivation of foodborne pathogens on buckwheat seeds, and determined the germination rates of seeds and the quality of sprouts following combination treatment.

METHODS AND RESULTS

Buckwheat seeds inoculated with Salmonella Typhimurium and Listeria monocytogenes were treated with CP, HW, CP + HW, VP + HW, or CP + VP + HW. The germination rates of the HW-, CP + HW-, VP + HW-, and CP + VP + HW-treated seeds and the antioxidant activities and rutin contents of the CP + HW- and CP + VP + HW-treated sprouts were determined. HW, CP + HW, and CP + VP + HW were found to reduce the levels of the two pathogens to below the detection limit (1.0 log CFU g-1) at 70°C. However, HW and CP + HW significantly reduced the germination rate of buckwheat seeds. CP + VP + HW did not affect the germination rate of seeds nor the antioxidant activities and rutin content of buckwheat sprouts.

CONCLUSIONS

These results indicate that CP + VP + HW can be used as a novel control method to reduce foodborne pathogens in seeds without causing quality deterioration.

Perspectives for the creation of a new type of vaccine preparations based on pseudovirus particles using polio vaccine as an example

Traditional antiviral vaccines are currently created by inactivating the virus chemically, most often using formaldehyde or β-propiolactone. These approaches are not optimal since they negatively affect the safety of the antigenic determinants of the inactivated particles and require additional purification stages. The most promising platforms for creating vaccines are based on pseudoviruses, i.e., viruses that have completely preserved the outer shell (capsid), while losing the ability to reproduce owing to the destruction of the genome. The irradiation of viruses with electron beam is the optimal way to create pseudoviral particles. In this review, with the example of the poliovirus, the main algorithms that can be applied to characterize pseudoviral particles functionally and structurally in the process of creating a vaccine preparation are presented. These algorithms are, namely, the analysis of the degree of genome destruction and coimmunogenicity. The structure of the poliovirus and methods of its inactivation are considered. Methods for assessing residual infectivity and immunogenicity are proposed for the functional characterization of pseudoviruses. Genome integrity analysis approaches, atomic force and electron microscopy, surface plasmon resonance, and bioelectrochemical methods are crucial to structural characterization of the pseudovirus particles.

Prefrontal activity sharpens spatial sensitivity of extrastriate neurons

Prefrontal cortex is known to exert its control over representation of visual signals in extrastriate areas such as V4. Frontal Eye Field (FEF) is suggested to be the proxy for the prefrontal control of visual signals. However, it is not known which aspects of sensory representation within extrastriate areas are under the influence of FEF activity. We employed a causal manipulation to examine how FEF activity contributes to spatial sensitivity of extrastriate neurons. Finding FEF and V4 areas with overlapping response field (RF) in two macaque monkeys, we recorded V4 responses before and after inactivation of the overlapping FEF. We assessed spatial sensitivity of V4 neurons in terms of their response gain, RF spread, coding capacity, and spatial discriminability. Unexpectedly, we found that in the absence of FEF activity, spontaneous and visually-evoked activity of V4 neurons both increase and their RFs enlarge. However, assessing the spatial sensitivity within V4, we found that these changes were associated with a reduction in the ability of V4 neurons to represent spatial information: After FEF inactivation, V4 neurons showed a reduced response gain and a decrease in their spatial discriminability and coding capacity. These results show the necessity of FEF activity for shaping spatial responses of extrastriate neurons and indicates the importance of FEF inputs in sharpening the sensitivity of V4 responses.

Impacts of Surface Characteristics and Dew Point on the Blue-Light (BL405) Inactivation of Viruses

The increased prevalence of multidrug-resistant organisms (MDROs), healthcare associated infections (HAIs), and the recent COVID-19 pandemic has caused the photoinactivation industry to explore alternative wavelengths. Blue light (BL405) has gained significant interest as it is much less harmful to the skin and eyes than traditional germicidal wavelengths; therefore, in theory, it can be used continuously with human exposure. At present, the viricidal effects of BL405 are largely unknown as the literature predominately addresses bacterial disinfection performed with this wavelength. This work provides novel findings to the industry, reporting on the virucidal effects of BL405 on surfaces. This research utilizes three surfaces: ceramic, PTFE, and stainless steel. The efficacy of BL405 inactivation varied by surface type, which was due to surface characteristics, such as the contact angle, porosity, zeta potential, and reflectivity. Additionally, the effect of the dew point on BL405 inactivation efficacy was determined. This research is the first to study the effects of the dew point on the virucidal effectiveness of BL405 surface inactivation. The effects of the dew point were significant for all surfaces and the control experiments. The high-dew-point conditions (18 °C) yielded higher levels of BL405 inactivation and viral degradation for the experiments and controls, respectively.

Ceramic absorbed with calcium bicarbonate mesoscopic crystals partially inactivate scrapie prions

Prion diseases are fatal neurodegenerative disorders affecting both humans and animals. The causative agent, prion, is extremely resistant to common disinfection procedures. Thus, effective prion inactivation strategies using relatively safe and less corrosive disinfectants are required. A solution containing CAC-717, mesoscopic crystals of calcium bicarbonate, exerts both antimicrobial and virucidal activities without apparent harmful effects. This study demonstrated that combined treatment with CAC-717 absorbed on ceramic (CAC-717 ceramic) and sodium dodecyl sulfate (SDS) substantially reduced the protein misfolding cyclic amplification (PMCA) seeding activity of Chandler strain scrapie mouse-brain homogenates (ScBH). Additionally, bioassays demonstrated that ScBH-inoculated mice treated with CAC-717 ceramic in combination with sodium dodecyl sulfate (SDS) did not develop disease. Furthermore, this combination effectively inactivated PMCA seeding activity on ScBH-coated stainless-steel wires below the detection limit. Overall, the findings suggest that combined treatment with CAC-717 ceramic and SDS represents a promising and less damaging approach for prion inactivation.

The "life-span" of lytic polysaccharide monooxygenases (LPMOs) correlates to the number of turnovers in the reductant peroxidase reaction

Lytic polysaccharide monooxygenases (LPMOs) are monocopper enzymes that degrade the insoluble crystalline polysaccharides cellulose and chitin. Besides the H2O2 cosubstrate, the cleavage of glycosidic bonds by LPMOs depends on the presence of a reductant needed to bring the enzyme into its reduced, catalytically active Cu(I) state. Reduced LPMOs that are not bound to substrate catalyze reductant peroxidase reactions, which may lead to oxidative damage and irreversible inactivation of the enzyme. However, the kinetics of this reaction remain largely unknown, as do possible variations between LPMOs belonging to different families. Here, we describe the kinetic characterization of two fungal family AA9 LPMOs, TrAA9A of Trichoderma reesei and NcAA9C of Neurospora crassa, and two bacterial AA10 LPMOs, ScAA10C of Streptomyces coelicolor and SmAA10A of Serratia marcescens. We found peroxidation of ascorbic acid and methyl-hydroquinone resulted in the same probability of LPMO inactivation (pi), suggesting that inactivation is independent of the nature of the reductant. We showed the fungal enzymes were clearly more resistant toward inactivation, having pi values of less than 0.01, whereas the pi for SmAA10A was an order of magnitude higher. However, the fungal enzymes also showed higher catalytic efficiencies (kcat/KM(H2O2)) for the reductant peroxidase reaction. This inverse linear correlation between the kcat/KM(H2O2) and pi suggests that, although having different life spans in terms of the number of turnovers in the reductant peroxidase reaction, LPMOs that are not bound to substrates have similar half-lives. These findings have not only potential biological but also industrial implications.

Viability of Veterinary-Relevant Viruses in Decomposing Tissues over a 90-Day Period Using an In-Vitro System

Depopulation is frequently employed during outbreaks of high-impact animal diseases. Security breaches in sites managing mortality may jeopardize pathogen control efforts as infected carcasses can serve as an infection source. This study evaluated the viability and nucleic acid detection of veterinary-relevant viruses or their surrogates in decomposing tissues. The used viruses were: Senecavirus A1 (SVA), feline calicivirus (FCV), bovine viral diarrhea virus (BVDV), porcine epidemic diarrhea virus (PEDV), bovine alphaherpesvirus 1 (BoHV-1), and swinepox virus (SwPV). Viruses were spiked in three decomposing tissues (swine bone marrow and spleen, and bovine bone marrow) and maintained for 90 days. Samples were kept under two temperature conditions resembling the average soil temperature in central Oklahoma, US, during the winter and summer (5.5 °C and 29.4 °C). At 5.5 °C, SVA and FCV remained viable over the 90 days of the study, followed by BVDV (75 days), BoHV-1 and SwPV (60 days), and PEDV (10 days). At 29.4 °C, SVA remained viable for 45 days, followed by BVDV and BoHV-1 (14 days). SwPV was viable for 10 days, whereas FCV and PEDV were viable for 5 days. Overall, viral nucleic acid detection was not significantly altered during the study. These findings support decision-making and risk management in sites overseeing animal mortality.

Mild Heat Treatment and Biopreservatives for Artisanal Raw Milk Cheeses: Reducing Microbial Spoilage and Extending Shelf-Life through Thermisation, Plant Extracts and Lactic Acid Bacteria

The microbial quality of raw milk artisanal cheeses is not always guaranteed due to the possible presence of pathogens in raw milk that can survive during manufacture and maturation. In this work, an overview of the existing information concerning lactic acid bacteria and plant extracts as antimicrobial agents is provided, as well as thermisation as a strategy to avoid pasteurisation and its negative impact on the sensory characteristics of artisanal cheeses. The mechanisms of antimicrobial action, advantages, limitations and, when applicable, relevant commercial applications are discussed. Plant extracts and lactic acid bacteria appear to be effective approaches to reduce microbial contamination in artisanal raw milk cheeses as a result of their constituents (for example, phenolic compounds in plant extracts), production of antimicrobial substances (such as organic acids and bacteriocins, in the case of lactic acid bacteria), or other mechanisms and their combinations. Thermisation was also confirmed as an effective heat inactivation strategy, causing the impairment of cellular structures and functions. This review also provides insight into the potential constraints of each of the approaches, hence pointing towards the direction of future research.

Virus Behavior after UV254 Treatment of Materials with Different Surface Properties

The COVID-19 pandemic highlighted the limitations in scientific and engineering understanding of applying germicidal UV to surfaces. This study combines surface characterization, viral retention, and the related UV dose response to evaluate the effectiveness of UV254 as a viral inactivation technology on five surfaces: aluminum, ceramic, Formica laminate, PTFE and stainless steel. Images of each surface were determined using SEM (Scanning Electron Microscopy), which produced a detailed characterization of the surfaces at a nanometer scale. From the SEM images, the surface porosity of each material was calculated. Through further analysis, it was determined that surface porosity, surface roughness, contact angle, and zeta potential correlate to viral retention on the material. The imaging revealed that the aluminum surface, after repeated treatment, is highly oxidized, increasing surface area and surface porosity. These interactions are important as they prevent the recovery of MS-2 without exposure to UV254. The dose response curve for PTFE was steeper than ceramic, Formica laminate and stainless steel, as inactivation to the detection limit was achieved at 25 mJ/cm2. These findings are consistent with well-established literature indicating UV reflectivity of PTFE is maximized. Statistical testing reinforced that the efficacy of UV254 for surface inactivation varies by surface type.

Inactivation influences the extent of inhibition of voltage-gated Ca+2 channels by Gem-implications for channelopathies

Voltage-gated Ca2+ channels (VGCC) directly control muscle contraction and neurotransmitter release, and slower processes such as cell differentiation, migration, and death. They are potently inhibited by RGK GTP-ases (Rem, Rem2, Rad, and Gem/Kir), which decrease Ca2+ channel membrane expression, as well as directly inhibit membrane-resident channels. The mechanisms of membrane-resident channel inhibition are difficult to study because RGK-overexpression causes complete or near complete channel inhibition. Using titrated levels of Gem expression in Xenopus oocytes to inhibit WT P/Q-type calcium channels by ∼50%, we show that inhibition is dependent on channel inactivation. Interestingly, fast-inactivating channels, including Familial Hemiplegic Migraine mutants, are more potently inhibited than WT channels, while slow-inactivating channels, such as those expressed with the Cavβ2a auxiliary subunit, are spared. We found similar results in L-type channels, and, remarkably, Timothy Syndrome mutant channels were insensitive to Gem inhibition. Further results suggest that RGKs slow channel recovery from inactivation and further implicate RGKs as likely modulating factors in channelopathies.

Virus Inactivation by Formaldehyde and Common Lysis Buffers

Numerous mammalian viruses are routinely analyzed in clinical diagnostic laboratories around the globe or serve as indispensable model systems in viral research. Potentially infectious viral entities are handled as blood, biopsies, or cell and tissue culture samples. Countless protocols describe methods for virus fixation and inactivation, yet for many, a formal proof of safety and completeness of inactivation remains to be shown. While modern nucleic acid extraction methods work quite effectively, data are largely lacking on possible residual viral infectivity, e.g., when assessed after extended culture times, which maximizes the sensitivity for low levels of residual infectiousness. Therefore, we examined the potency and completeness of inactivation procedures on virus-containing specimens when applying commonly used fixatives like formaldehyde or nucleic acid extraction/lysis buffers. Typical representatives of different virus classes, including RNA and DNA viruses, enveloped and non-enveloped, such as adenovirus, enterovirus, lentivirus, and coronavirus, were used, and the reduction in the in vitro infectiousness was assessed for standard protocols. Overall, a 30-minute incubation with formaldehyde at room temperature effectively inactivated all tested enveloped and non-enveloped viruses. Full inactivation of HIV-1 and ECHO-11 was also achieved with all buffers in the test, whereas for SARS-CoV-2 and AdV-5, only five of the seven lysis buffers were fully effective under the tested conditions.

Inactive PARP1 causes embryonic lethality and genome instability in a dominant-negative manner

PARP1 (poly-ADP ribose polymerase 1) is recruited and activated by DNA strand breaks, catalyzing the generation of poly-ADP-ribose (PAR) chains from NAD+. PAR relaxes chromatin and recruits other DNA repair factors, including XRCC1 and DNA Ligase 3, to maintain genomic stability. Here we show that, in contrast to the normal development of Parp1-null mice, heterozygous expression of catalytically inactive Parp1 (E988A, Parp1+/A) acts in a dominant-negative manner to disrupt murine embryogenesis. As such, all the surviving F1 Parp1+/A mice are chimeras with mixed Parp1+/AN (neoR retention) cells that act similarly to Parp1+/-. Pure F2 Parp1+/A embryos were found at Mendelian ratios at the E3.5 blastocyst stage but died before E9.5. Compared to Parp1-/- cells, genotype and expression-validated pure Parp1+/A cells retain significant ADP-ribosylation and PARylation activities but accumulate markedly higher levels of sister chromatid exchange and mitotic bridges. Despite proficiency for homologous recombination and nonhomologous end-joining measured by reporter assays and supported by normal lymphocyte and germ cell development, Parp1+/A cells are hypersensitive to base damages, radiation, and Topoisomerase I and II inhibition. The sensitivity of Parp1+/A cells to base damages and Topo inhibitors exceed Parp1-/- controls. The findings show that the enzymatically inactive PARP1 dominant negatively blocks DNA repair in selective pathways beyond wild-type PARP1 and establishes a crucial physiological difference between PARP1 inactivation vs. deletion. As a result, the expression of enzymatically inactive PARP1 from one allele is sufficient to abrogate murine embryonic development, providing a mechanism for the on-target side effect of PARP inhibitors used for cancer therapy.

Predicting the effect of mutations to investigate recent events of selection across 60,472 Escherichia coli strains

Microbial genomics studies focusing on the dynamics of selection have often used a small number of distant genomes. As a result, they could only analyze mutations that had become fixed during the divergence between species. However, thousands of genomes of some species are now available in public databases, thanks to high-throughput sequencing. These data provide a more complete picture of the polymorphisms segregating within a species, offering a unique insight into the processes that shape the recent evolution of a species. In this study, we present GLASS (Gene-Level Amino-acid Score Shift), a selection test that is based on the predicted effects of amino acid changes. By comparing the distribution of effects of mutations observed in a gene to the expectation in the absence of selection, GLASS can quantify the intensity of selection. We applied GLASS to a dataset of 60,472 Escherichia coli strains and used this to reexamine the longstanding debate about the role of essentiality versus expression level in the rate of protein evolution. We found that selection has contrasting short-term and long-term dynamics, with essential genes being subject to strong purifying selection in the short term, while expression level determines the rate of gene evolution in the long term. GLASS also found an overrepresentation of inactivating mutations in specific transcription factors, such as efflux pump repressors, which is consistent with selection for antibiotic resistance. These gene-inactivating polymorphisms do not reach fixation, suggesting another contrast between short-term fitness gains and long-term counterselection.

Evaluation of the Inactivation Efficacy of Four Disinfectants for Feline Parvovirus Derived from Giant Panda

Feline panleukopenia (FPL) is a highly contagious acute infectious disease caused by feline parvovirus (FPV). FPV has also been found in giant pandas with clinical signs of vomiting and mild diarrhea, posing a threat to this vulnerable species. Cleaning and disinfection may be one of the most efficacious ways to prevent FPV spread in the habitat of giant pandas. This study evaluated the inactivation effect of peracetic acid (PAA), povidone-iodine (PVP-I), glutaral and deciquam solution (JM) and Virkon S. The tissue culture infective dose (TCID₅₀) assay indicated that the virus may be totally inactivated by JM, PAA and Virkon S. Meanwhile, the hemagglutination (HA) assay showed a high inactivation efficiency of PAA and Virkon S. The analysis of Western blot revealed that PAA, Virkon S and JM can inhibit the structural protein synthesis. Taken together, our findings demonstrated that PAA could rapidly and efficiently inactivate FPV, representing an efficacious disinfectant for FPV control.

Assessment on the efficacy of methods 2 to 5 and method 7 set out in Commission Regulation (EU) No 142/2011 to inactivate relevant pathogens when producing processed animal protein of porcine origin intended to feed poultry and aquaculture animals

An assessment was conducted on the level of inactivation of relevant pathogens that could be present in processed animal protein of porcine origin intended to feed poultry and aquaculture animals when methods 2 to 5 and method 7, as detailed in Regulation (EU) No 142/2011, are applied. Five approved scenarios were selected for method 7. Salmonella Senftenberg, Enterococcus faecalis, spores of Clostridium perfringens and parvoviruses were shortlisted as target indicators. Inactivation parameters for these indicators were extracted from extensive literature search and a recent EFSA scientific opinion. An adapted Bigelow model was fitted to retrieved data to estimate the probability that methods 2 to 5, in coincidental and consecutive modes, and the five scenarios of method 7 are able to achieve a 5 log10 and a 3 log10 reduction of bacterial indicators and parvoviruses, respectively. Spores of C. perfringens were the indicator with the lowest probability of achieving the target reduction by methods 2 to 5, in coincidental and consecutive mode, and by the five considered scenarios of method 7. An expert knowledge elicitation was conducted to estimate the certainty of achieving a 5 log10 reduction of spores of C. perfringens considering the results of the model and additional evidence. A 5 log10 reduction of C. perfringens spores was judged: 99-100% certain for methods 2 and 3 in coincidental mode; 98-100% certain for method 7 scenario 3; 80-99% certain for method 5 in coincidental mode; 66-100% certain for method 4 in coincidental mode and for method 7 scenarios 4 and 5; 25-75% certain for method 7 scenario 2; and 0-5% certain for method 7 scenario 1. Higher certainty is expected for methods 2 to 5 in consecutive mode compared to coincidental mode.

Evaluation of the Efficacy of Commercial Disinfectants against African Swine Fever Virus

African swine fever (ASF) is an economically important disease due to high morbidity and mortality rates and the ability to affect all ages and breeds of pigs. Biosecurity measures to prevent the spread of the causative agent, African swine fever virus (ASFV), include prescriptive cleaning and disinfection procedures. The aim of this study was to establish the biocidal effects of twenty-four commercially available disinfectants including oxidizing agents, acids, aldehydes, formic acids, phenol, and mixed-class chemistries against ASFV. The products were prepared according to the manufacturer's instructions and a suspension assay was performed with ASFV strain, BA71V using Vero cells (African green monkey cells) to test efficacy in reducing ASFV infection of cells. Generally, disinfectants containing formic acid and phenolic compounds, as well as oxidizing agents reduced viral titers of ASFV by over 4 log₁₀ at temperatures ranging from 4 °C to 20 °C. Hydrogen peroxide, aldehyde, and quaternary ammonium compounds containing disinfectants were cytotoxic, limiting the detection of viral infectivity reductions to less than 4 log₁₀. These preliminary results can be used to target research on disinfectants which contain active ingredients with known efficacy against ASFV under conditions recommended for the country where their use will be applied.

Innovative nonthermal technologies for inactivation of emerging foodborne viruses

Various foodborne viruses have been associated with human health during the last decade, causing gastroenteritis and a huge economic burden worldwide. Furthermore, the emergence of new variants of infectious viruses is growing continuously. Inactivation of foodborne viruses in the food industry is a formidable task because although viruses cannot grow in foods, they can survive in the food matrix during food processing and storage environments. Conventional inactivation methods pose various drawbacks, necessitating more effective and environmentally friendly techniques for controlling foodborne viruses during food production and processing. Various inactivation approaches for controlling foodborne viruses have been attempted in the food industry. However, some traditionally used techniques, such as disinfectant-based or heat treatment, are not always efficient. Nonthermal techniques are considered a new platform for effective and safe treatment to inactivate foodborne viruses. This review focuses on foodborne viruses commonly associated with human gastroenteritis, including newly emerged viruses, such as sapovirus and Aichi virus. It also investigates the use of chemical and nonthermal physical treatments as effective technologies to inactivate foodborne viruses.

SARS-CoV-2 detection and inactivation in water and wastewater: Review on analytical methods, limitations and future research recommendations

AbstractSevere acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been detected in wastewater. Wastewater-based epidemiology (WBE) is a practical and cost-effective tool for the assessment and controlling of pandemics and probably for examining SARS-CoV-2 presence. Implementation of WBE during the outbreaks is not without limitations. Temperature, suspended solids, pH, and disinfectants affect the stability of viruses in wastewater. Due to these limitations, instruments and techniques have been utilized to detect SARS-CoV-2. SARS-CoV-2 has been detected in sewage using various concentration methods and computer-aided analyzes. RT-qPCR, ddRT-PCR, multiplex PCR, RT-LAMP, and electrochemical immunosensors have been employed to detect low levels of viral contamination. Inactivation of SARS-CoV-2 is a crucial preventive measure against coronavirus disease 2019 (COVID-19). To better assess the role of wastewater as a transmission route, detection, and quantification methods need to be refined. In this paper, the latest improvements in quantification, detection, and inactivation of SARS-CoV-2 in wastewater are explained. Finally, limitations and future research recommendations are thoroughly described.

Stepwise O2-Induced Rearrangement and Disassembly of the [NiFe4(OH)(µ3-S)4] Active Site Cluster of CO Dehydrogenase

Ni,Fe-containing carbon monoxide dehydrogenases (CODHs) catalyze the reversible reduction of carbon dioxide to carbon monoxide. CODHs are found in anaerobic microorganisms and can rapidly lose their activity when exposed to air. What causes the loss of activity is unclear. Here, we analyzed the time-dependent structural changes induced by the presence of air on the metal centers of CODH-II. We show that inactivation is a multistep process. In a reversible step, the open coordination site on the Ni ion is blocked by a Ni,Fe-bridging µ-sulfido or chlorido ligand. Blocking this open coordination site with a cyanide ligand stabilizes the cluster against O2-induced decomposition, indicating that O2 attacks at the Ni ion. In the subsequent irreversible phase, nickel is lost, the Fe ions rearrange and the sulfido ligands disappear. Our data are consistent with a reversible reductive reactivation mechanism to protect CODHs from transient over-oxidation.

Enhanced sodium channel inactivation by temperature and FHF2 deficiency blocks heat nociception

ABSTRACT

Transient voltage-gated sodium currents are essential for the initiation and conduction of action potentials in neurons and cardiomyocytes. The amplitude and duration of sodium currents are tuned by intracellular fibroblast growth factor homologous factors (FHFs/iFGFs) that associate with the cytoplasmic tails of voltage-gated sodium channels (Na v s), and genetic ablation of Fhf genes disturbs neurological and cardiac functions. Among reported phenotypes, Fhf2null mice undergo lethal hyperthermia-induced cardiac conduction block attributable to the combined effects of FHF2 deficiency and elevated temperature on the cardiac sodium channel (Na v 1.5) inactivation rate. Fhf2null mice also display a lack of heat nociception, while retaining other somatosensory capabilities. Here, we use electrophysiological and computational methods to show that the heat nociception deficit can be explained by the combined effects of elevated temperature and FHF2 deficiency on the fast inactivation gating of Na v 1.7 and tetrodotoxin-resistant sodium channels expressed in dorsal root ganglion C fibers. Hence, neurological and cardiac heat-associated deficits in Fhf2null mice derive from shared impacts of FHF deficiency and temperature towards Na v inactivation gating kinetics in distinct tissues.

The Role of Probiotics in Improving Food Safety: Inactivation of Pathogens and Biological Toxins

Currently, many advances have been made in avoiding food contamination by numerous pathogenic and toxigenic microorganisms. Many studies have shown that different probiotics, in addition to having beneficial effects on the host's health, have a very good ability to eliminate and neutralize pathogens and their toxins in foods which leads to enhanced food safety. The present review purposes to comprehensively discuss the role of probiotics in improving food safety by inactivating pathogens (bacterial, fungal, viral, and parasite agents) and neutralizing their toxins in food products. Some recent examples in terms of the anti-microbial activities of probiotics in the body after consuming contaminated food have also been mentioned. This review shows that different probiotics have the potential to inactivate pathogens and neutralize and detoxify various biological agents in foods, as well as in the host body after consumption.

The Biosafety Research Road Map: The Search for Evidence to Support Practices in the Laboratory-Shigella spp

Introduction

Shigella bacteria cause shigellosis, a gastrointestinal infection most often acquired from contaminated food or water.

Methods

In this review, the general characteristics of Shigella bacteria are described, cases of laboratory-acquired infections (LAIs) are discussed, and evidence gaps in current biosafety practices are identified.

Results

LAIs are undoubtedly under-reported. Owing to the low infectious dose, rigorous biosafety level 2 practices are required to prevent LAIs resulting from sample manipulation or contact with infected surfaces.

Conclusions

It is recommended that, before laboratory work with Shigella, an evidence-based risk assessment be conducted. Particular emphasis should be placed on personal protective equipment, handwashing, and containment practices for procedures that generate aerosols or droplets.

[Selection of conditions for effective inactivation of Pseudopestis avium virus (Paramyxoviridae: Orthoavulovirus: Avian orthoavulovirus 1) for the production of a Newcastle disease vaccine]

INTRODUCTION

Newcastle disease (ND) is classified as especially dangerous pathogen. Its primary source is an infected or recovered bird. The virus shedding begins just in a day after infection, and virus remains in the body for another 2-4 months after the recovery. The complexity of the final elimination of the causative agent of the disease lies in its ability for long-term preservation in the external environment and the possibility of constant circulation in one complex between groups of birds of different sex and age. Therefore, the main element of protecting birds from ND is immunoprophylaxis that is based on vaccines containing an inactivated ND virus (NDV). The aim of the work ‒ is to optimize the parameters of inactivation of the NDV actual strain H with formaldehyde at final concentrations of 0.01, 0.025, 0.05, and 0.1% under temperature conditions of 20 2 and 37 0.5 C.

MATERIALS AND METHODS

We used a virus-containing suspension of the NDV strain H with an initial biological activity of 10.75 lg EID50/cm3 grown by cultivation in 10-day-old developing chick embryos.

RESULTS

On the 16th day after the administration of the tested suspensions of NDV inactivated at different temperatures and concentrations of the inactivant , the geometric mean titers of antibodies to NDV in sera of vaccinated birds were at least 1 : 63 in the hemagglutination inhibition reaction, indicating that the studied inactivated suspensions were antigenically active.

CONCLUSION

The optimal parameters of the inactivation mode (final concentration, temperature and time of inactivation) of the NDV strain H were established. The inactivation process at 37 0.5 C with inactivant concentrations of 0.01, 0.025, 0.05, and 0.1% lasts up to 72, 22, 18, and 12 hours, respectively. The inactivation process at 20 2 C with inactivant concentrations of 0.05 and 0.1% lasts up to 22 and 18 hours, respectively.

Static Aerated Composting of African Swine Fever Virus-Infected Swine Carcasses with Rice Hulls and Sawdust

Identifying and ensuring the inactivation of the African Swine Fever virus in deadstock is a gap in the swine industry's knowledge and response capabilities. The results of our study demonstrate that ASFv in deadstock was inactivated using static aerated composting as the carcass disposal method. Replicated compost piles with whole market hogs and two different carbon sources were constructed. In-situ bags containing ASFv-infected spleen tissue were placed alongside each of the carcasses and throughout the pile. The bags were extracted at days 0, 1, 3, 7, 14, 28, 56, and 144 for ASFv detection and isolation. Real-time PCR results showed that DNA of ASFv was detected in all samples tested on day 28. The virus concentration identified through virus isolation was found to be below the detection limit by day 3 in rice hulls and by day 7 in sawdust. Given the slope of the decay, near-zero concentration with 99.9% confidence occurred at 5.0 days in rice hulls and at 6.4 days in sawdust. Additionally, the result of virus isolation also showed that the virus in bone marrow samples collected at 28 days was inactivated.