Biological agents with potential for misuse: a historical perspective and defensive measures

Clinically Evaluated COVID-19 Drugs with Therapeutic Potential for Biological Warfare Agents

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) outbreak resulted in hundreds of millions of coronavirus cases, as well as millions of deaths worldwide. Coronavirus Disease 2019 (COVID-19), the disease resulting from exposure to this pathogen, is characterized, among other features, by a pulmonary pathology, which can progress to "cytokine storm", acute respiratory distress syndrome (ARDS), respiratory failure and death. Vaccines are the unsurpassed strategy for prevention and protection against the SARS-CoV-2 infection. However, there is still an extremely high number of severely ill people from at-risk populations. This may be attributed to waning immune response, variant-induced breakthrough infections, unvaccinated population, etc. It is therefore of high importance to utilize pharmacological-based treatments, despite the progression of the global vaccination campaign. Until the approval of Paxlovid, an efficient and highly selective anti-SARS-CoV-2 drug, and the broad-spectrum antiviral agent Lagevrio, many pharmacological-based countermeasures were, and still are, being evaluated in clinical trials. Some of these are host-directed therapies (HDTs), which modulate the endogenic response against the virus, and therefore may confer efficient protection against a wide array of pathogens. These could potentially include Biological Warfare Agents (BWAs), exposure to which may lead to mass casualties due to disease severity and a possible lack of efficient treatment. In this review, we assessed the recent literature on drugs under advanced clinical evaluation for COVID-19 with broad spectrum activity, including antiviral agents and HDTs, which may be relevant for future coping with BWAs, as well as with other agents, in particular respiratory infections.

Immunosensors for Assay of Toxic Biological Warfare Agents

An immunosensor for the assay of toxic biological warfare agents is a biosensor suitable for detecting hazardous substances such as aflatoxin, botulinum toxin, ricin, Shiga toxin, and others. The application of immunosensors is used in outdoor assays, point-of-care tests, as a spare method for more expensive devices, and even in the laboratory as a standard analytical method. Some immunosensors, such as automated flow-through analyzers or lateral flow tests, have been successfully commercialized as tools for toxins assay, but the research is ongoing. New devices are being developed, and the use of advanced materials and assay techniques make immunosensors highly competitive analytical devices in the field of toxic biological warfare agents assay. This review summarizes facts about current applications and new trends of immunosensors regarding recent papers in this area.

County-Level Planning for Efficient Distribution of Emergency Medical Countermeasures with RealOpt Software

Emergency preparedness systems plan for antibiotic distribution and vaccine administration to respond to public health threats. The arrival of a COVID-19 vaccine underscores the importance of organized logistics for rapid administration to populations. The US Centers for Disease Control and Prevention Cities Readiness Initiative encourages frontline responders from 72 US cities and metropolitan statistical areas to use planning software, such as RealOpt-POD-v8.0.2, to design dispensing operations and predict staffing needs. However, planning can be difficult for local jurisdictions given uncertainty about how long it may take to complete various processes during a dispensing operation, including assessment of countermeasure needs for each person (eg, based on age or pregnancy status) and the careful dispensing of countermeasures and accompanying education. The Union County Health Department in Ohio gathered data on the timing of typical processes for an anthrax medical countermeasures distribution site through a small-scale drill and used these data to parameterize a RealOpt model capable of serving the rural county's population of just over 50,000 people within 24 hours. Results help fill a gap in parameterizing RealOpt-based planning models by highlighting the use of a small-scale drill to inform time estimates, which can be applied to RealOpt as part of county-level planning in advance of larger-scale drills to evaluate dispensing capabilities and effectiveness. The findings provide a methodological basis of future resource typing for adaptable and scalable dispensing, particularly for rural areas. Both the approach and resulting antibiotics dispensing schematic presented here could be tailored to support planning for population-based countermeasure administration to combat emerging pandemics.

Biodefense Implications of New-World Hantaviruses

Hantaviruses, part of the Bunyaviridae family, are a genus of negative-sense, single-stranded RNA viruses that cause two major diseases: New-World Hantavirus Cardiopulmonary Syndrome and Old-World Hemorrhagic Fever with Renal Syndrome. Hantaviruses generally are found worldwide with each disease corresponding to their respective hemispheres. New-World Hantaviruses spread by specific rodent-host reservoirs and are categorized as emerging viruses that pose a threat to global health and security due to their high mortality rate and ease of transmission. Incidentally, reports of Hantavirus categorization as a bioweapon are often contradicted as both US National Institute of Allergy and Infectious Diseases and the Centers for Disease Control and Prevention refer to them as Category A and C bioagents respectively, each retaining qualitative levels of importance and severity. Concerns of Hantavirus being engineered into a novel bioagent has been thwarted by Hantaviruses being difficult to culture, isolate, and purify limiting its ability to be weaponized. However, the natural properties of Hantaviruses pose a threat that can be exploited by conventional and unconventional forces. This review seeks to clarify the categorization of Hantaviruses as a bioweapon, whilst defining the practicality of employing New-World Hantaviruses and their effect on armies, infrastructure, and civilian targets.

Bioterrorismo: capacitar para responder

RESUMO A utilização de agentes biológicos com a finalidade de aterrorizar inimigos surgiu há muitos séculos. Essa ação foi popularizada como bioterrorismo. Ataques bioterroristas são perigosos devido ao envolvimento de diversos fatores, como a forma silenciosa na qual pode ocorrer, o tipo e a forma de transmissão do agente biológico utilizado, dependendo do objetivo do ataque. Para prevenção da contaminação por esses agentes, os profissionais que irão atuar no seu combate devem possuir conhecimentos a respeito dos mecanismos de ação e de disseminação desses patógenos, bem como a adequada forma de sua neutralização e eliminação; além de saber escolher os equipamentos de proteção, tanto de uso individual quanto coletivo, adequados. Diante disso, tais equipes de ação necessitam ser bem capacitadas e treinadas. O objetivo deste estudo foi analisar, na literatura, os modos de treinamentos existentes no mundo para os profissionais de primeira resposta aos ataques envolvendo agentes Químico, Biológico, Radiológico ou Nuclear (QBRN). A partir de uma revisão integrativa, encontraram-se três artigos, em um período de 20 anos. Conclui-se que são muito escassos os estudos nessa área e que mais pesquisas e treinamentos para este tipo de evento devem ser realizados no mundo inteiro.

A graphene oxide-based strand displacement amplification platform for ricin detection using aptamer as recognition element

The toxic plant protein ricin is a potential agent for criminal or bioterrorist attacks due to the wide availability and relative ease of preparation. Herein, we developed a novel strategy for the detection of ricin B-chain (RTB) based on isothermal strand-displacement polymerase reaction (ISDPR) by using aptamer as a recognition element and graphene oxide (GO) as a low background platform. In this method, ricin-binding aptamer (RBA) hybridized with a short blocker firstly, and then was immobilized on the surface of streptavidin-coated magnetic beads (MBs). The addition of RTB could release the blocker, which could hybridize with the dye-modified hairpin probe and trigger the ISDPR, resulting in high fluorescence intensity. In the absence of RTB, however, the fluorescence of the dye could be quenched strongly by GO, resulting in the extremely low background signal. Thus, RTB could be sensitively detected by the significantly increased fluorescence signal. The linear range of the current analytical system was from 0.75μg/mL to 100μg/mL and the limit of detection (3σ) was 0.6μg/mL. This method has been successfully utilized for the detection of both the RTB and the entire ricin toxin in real samples, and it could be generalized to any kind of target detection based on an appropriate aptamer.

Escherichia coli growth and transport in the presence of nanosilver under variable growth conditions

Nanosilver (silver nanoparticles) has the ability to anchor to the bacterial cell membrane and subsequently penetrate it, thereby causing structural changes (i.e., permeability) in the cell membrane and death of the cell. The bacterial responses to the presence of nanosilver usually vary depending on the concentration of nanosilver particles, exposure time and the bacterial physiological stage. Since bacterial anabolism dependents upon a stoichiometric ratio of carbon and inorganic elements (nutrients), the macronutrient ratio, i.e. carbon to nitrogen ratio (C/N) thus plays an important role of bacterial responses to the exposure of nanosilver. This study investigated the responses of Escherichia coli to the exposure of nanosilver under variable growth conditions. It was discovered that E. coli grown under different growth conditions had different responses to the presence of nanosilver. E. coli had least resistance to the toxicity of nanosilver when cultured under carbon-limited conditions. However, the presence of rhamnolipid, a commonly utilized biosurfactant for soil remediation increased the resistance of E. coli to nanosilver. The transport of E. coli cultured under carbon-limited conditions was further studied in silica sand columns. E. coli adsorption in silica sand increased when cultured in the presence of nanosilver. On the contrary, E. coli adsorption in silica sand was significantly reduced when cultured in the presence of rhamnolipid.

Advax-adjuvanted recombinant protective antigen provides protection against inhalational anthrax that is further enhanced by addition of murabutide adjuvant

Subunit vaccines against anthrax based on recombinant protective antigen (PA) potentially offer more consistent and less reactogenic anthrax vaccines but require adjuvants to achieve optimal immunogenicity. This study sought to determine in a murine model of pulmonary anthrax infection whether the polysaccharide adjuvant Advax or the innate immune adjuvant murabutide alone or together could enhance PA immunogenicity by comparison to an alum adjuvant. A single immunization with PA plus Advax adjuvant afforded significantly greater protection against aerosolized Bacillus anthracis Sterne strain 7702 than three immunizations with PA alone. Murabutide had a weaker adjuvant effect than Advax when used alone, but when murabutide was formulated together with Advax, an additive effect on immunogenicity and protection was observed, with complete protection after just two doses. The combined adjuvant formulation stimulated a robust, long-lasting B-cell memory response that protected mice against an aerosol challenge 18 months postimmunization with acceleration of the kinetics of the anamnestic IgG response to B. anthracis as reflected by ∼4-fold-higher anti-PA IgG titers by day 2 postchallenge versus mice that received PA with Alhydrogel. In addition, the combination of Advax plus murabutide induced approximately 3-fold-less inflammation than Alhydrogel as measured by in vivo imaging of cathepsin cleavage resulting from injection of ProSense 750. Thus, the combination of Advax and murabutide provided enhanced protection against inhalational anthrax with reduced localized inflammation, making this a promising next-generation anthrax vaccine adjuvanting strategy.

Reconfigurable acquisition system with integrated optics for a portable flow cytometer

Portable and inexpensive scientific instruments that are capable of performing point of care diagnostics are needed for applications such as disease detection and diagnosis in resource-poor settings, for water quality and food supply monitoring, and for biosurveillance activities in autonomous vehicles. In this paper, we describe the development of a compact flow cytometer built from three separate, customizable, and interchangeable modules. The instrument as configured in this work is being developed specifically for the detection of selected Centers for Disease Control (CDC) category B biothreat agents through a bead-based assay: E. coli O157:H7, Salmonella, Listeria, and Shigella. It has two-color excitation, three-color fluorescence and light scattering detection, embedded electronics, and capillary based flow. However, these attributes can be easily modified for other applications such as cluster of differentiation 4 (CD4) counting. Proof of concept is demonstrated through a 6-plex bead assay with the results compared to a commercially available benchtop-sized instrument.

Single domain antibodies for the detection of ricin using silicon photonic microring resonator arrays

Ricin is a lethal protein toxin derived from the castor bean plant. Given its notorious history as a biowarfare agent and homicidal weapon, ricin has been classified as a category B bioterrorism agent. Current ricin detection methods based on immunoassays lack the required sensitivity and specificity for many homeland security surveillance applications. Importantly, many conventional antibody-based methodologies are unable to distinguish ricin from RCA 120, a nontoxic protein also found in the castor bean plant. Single domain antibodies (sdAbs), which are recombinantly derived from immunized llamas, are known to have high affinities for ricin A or B chains and low cross-reactivity with RCA 120. Herein, we demonstrate the use of silicon photonic microring resonators for antibody affinity profiling and one-step ricin detection at concentrations down to 300 pM using a 15 min, label-free assay format. These sdAbs were also simultaneously compared with a commercial anti-RCA IgG antibody in a multicapture agent, single target immunoassay using arrays of microrings, which allowed direct comparison of sensitivity and specificity. A selected sdAb was also found to exhibit outstanding specificity against another biotoxin, saporin, which has mechanism of action similar to ricin. Given the rapidity, scalability, and multiplexing capability of this silicon-based technology, this work represents a step toward using microring resonator arrays for the sensitive and specific detection of biowarfare agents.

Learning virulent proteins from integrated query networks

Background

Methods of weakening and attenuating pathogens’ abilities to infect and propagate in a host, thus allowing the natural immune system to more easily decimate invaders, have gained attention as alternatives to broad-spectrum targeting approaches. The following work describes a technique to identifying proteins involved in virulence by relying on latent information computationally gathered across biological repositories, applicable to both generic and specific virulence categories.

Results

A lightweight method for data integration is used, which links information regarding a protein via a path-based query graph. A method of weighting is then applied to query graphs that can serve as input to various statistical classification methods for discrimination, and the combined usage of both data integration and learning methods are tested against the problem of both generalized and specific virulence function prediction.

Conclusions

This approach improves coverage of functional data over a protein. Moreover, while depending largely on noisy and potentially non-curated data from public sources, we find it outperforms other techniques to identification of general virulence factors and baseline remote homology detection methods for specific virulence categories.

Label-free detection of a bacterial pathogen using an immobilized siderophore, deferoxamine

Pathogenic bacteria obtain the iron necessary for survival by releasing an iron chelator, termed a siderophore, and retrieving the iron-siderophore complex via a cell surface siderophore receptor. We have exploited the high affinity of Yersinia enterocolitica for its siderophore, deferoxamine, to develop a rapid method for capture and identification of Yersinia. In this methodology, a deferoxamine-bovine serum albumin conjugate is printed onto a gold-plated chip in a parallel line pattern. After flowing a suspension of Yersinia across the siderophore-derivatized chip, any Yersinia that binds to the chip is detected by dark-field microscopy analysis of the scattered light, followed by Fourier transform analysis of the scattering pattern. Since peak intensities are found to correlate with pathogen concentration, pathogen titers as low as 10(3) cfu/ml can be readily detected. Moreover, immobilized deferoxamine can distinguish Y. enterocolitica, which binds ferrioxamine (deferoxamine-Fe), from Staphylococcus aureus, Mycobacterium smegmatis and Pseudomonas aeruginosa, which don't. Because human pathogens cannot easily mutate their iron retrieval systems without loss of viability, we suggest that few if any mutant Yersinia will emerge that can avoid detection. Together with previous results demonstrating selective capture of Pseudomonas aeruginosa by its immobilized siderophore (pyoverdin), these data suggest that pathogen-specific siderophores may constitute effective and immutable capture ligands for rapid detection and identification of their cognate pathogens.

Statistical approach to estimate vaccinia-specific neutralizing antibody titers using a high-throughput assay

Because of the bioterrorism threat posed by agents such as variola virus, considerable time, resources, and effort have been devoted to biodefense preparation. One avenue of this research has been the development of rapid, sensitive, high-throughput assays to validate immune responses to poxviruses. Here we describe the adaptation of a beta-galactosidase reporter-based vaccinia virus neutralization assay to large-scale use in a study that included over 1,000 subjects. We also describe the statistical methods involved in analyzing the large quantity of data generated. The assay and its associated methods should prove useful tools in monitoring immune responses to next-generation smallpox vaccines, studying poxvirus immunity, and evaluating therapeutic agents such as vaccinia virus immune globulin.

Efficacy of a vaccine based on protective antigen and killed spores against experimental inhalational anthrax

Protective antigen (PA)-based anthrax vaccines acting on toxins are less effective than live attenuated vaccines, suggesting that additional antigens may contribute to protective immunity. Several reports indicate that capsule or spore-associated antigens may enhance the protection afforded by PA. Addition of formaldehyde-inactivated spores (FIS) to PA (PA-FIS) elicits total protection against cutaneous anthrax. Nevertheless, vaccines that are effective against cutaneous anthrax may not be so against inhalational anthrax. The aim of this work was to optimize immunization with PA-FIS and to assess vaccine efficacy against inhalational anthrax. We assessed the immune response to recombinant anthrax PA from Bacillus anthracis (rPA)-FIS administered by various immunization protocols and the protection provided to mice and guinea pigs infected through the respiratory route with spores of a virulent strain of B. anthracis. Combined subcutaneous plus intranasal immunization of mice yielded a mucosal immunoglobulin G response to rPA that was more than 20 times higher than that in lung mucosal secretions after subcutaneous vaccination. The titers of toxin-neutralizing antibody and antispore antibody were also significantly higher: nine and eight times higher, respectively. The optimized immunization elicited total protection of mice intranasally infected with the virulent B. anthracis strain 17JB. Guinea pigs were fully protected, both against an intranasal challenge with 100 50% lethal doses (LD(50)) and against an aerosol with 75 LD(50) of spores of the highly virulent strain 9602. Conversely, immunization with PA alone did not elicit protection. These results demonstrate that the association of PA and spores is very much more effective than PA alone against experimental inhalational anthrax.

Properties and applications of antimicrobial peptides in biodefense against biological warfare threat agents

Recent advances in knowledge of the properties of antimicrobial peptides (AMPs) are reviewed. AMPs are typically small, positively charged, amphipathic peptides that interact electrostatically and non-stereospecifically with the bacterial cell membrane, resulting in its permeabilization and cell death. Classes of AMPs, their mechanisms of action, hemolytic activity, and cytotoxicity towards host cells are discussed. A particular focus is AMPs with potential for use in defense against biological warfare agents. Some AMPs cytotoxic to Bacillus anthracis have been described. Synthesis of these peptides in multivalent form leads to a synergistic increase in antibacterial activity. Strategies to enhance the potency, stability, and selectivity of AMPs are discussed.

Bioterrorism

Bioterrorism is defined as the deliberate and malicious deployment of microbial agents or their toxins as weapons in a non-combat setting, represents perhaps the most overt example of human behavior impacting epidemic infectious diseases. There is historical precedent for the use of biological agents against both military and civilian populations. The use of biological (and chemical) agents as weapons of war has been well documented. The German biological warfare program during World War I included covert infections of Allied livestock with anthrax and glanders. The Japanese army began conducting experiments on the effects of bacterial agents of biowarfare on Chinese prisoners in occupied Manchuria in 1932 at their infamous Unit 731. The United States began its own offensive biological weapons program in 1942 and, during its 28-year official existence, weaponized and stockpiled lethal biological agents, such as anthrax, as well as incapacitating agents, such as the etiologic agent of Q fever. There are some recent examples of bioterrorism, though not necessarily resulting in attacks causing morbidity or mortality, may serve as harbingers of future events. Saddam Hussein's regime in Iraq developed and deployed anthrax and botulinum-laden warheads in the years leading up to the Gulf War. The reasons that these weapons were never used in an actual attack probably had more to do with the implicit threat of overwhelming US retaliation and Iraqi technological deficiencies rather than the regime's reluctance to violate any moral principles. Biological agents have also been used to forward political ideologies: in 1984 a religious cult, intent on influencing voter turnout during a local election, contaminated restaurant salad bars in The Dalles, Oregon.

Investigating the Geminal Diamine Intermediate of Yersinia pestis Arginine Decarboxylase with Substrate, Product, and Inhibitors Using Single Wavelength Stopped-Flow Spectroscopy

The reaction mechanism of Yersinia pestis arginine decarboxylase has been investigated using a series of substrate, product, and inhibitors. Using single wavelength stopped-flow spectroscopy, novel mechanistic features were noted in the presence of the product, agmatine. By focusing on the excitation and emission wavelengths of the geminal diamine intermediate, we were able to monitor the formation and decay of two different geminal diamine species. Experiments revealed that the enzyme exists in two different conformational states--one that binds ligand and one that does not. The on and off rates for the conversion between the two conformational states was determined to be 390 s-1 and 880 s-1, respectively. The KD for agmatine binding was 6 mM. In addition, experiments revealed a pH-dependent conversion between two states of the enzyme. The deprotonated form of the enzyme binds ligand more slowly than the protonated form. The rates for the formation of the geminal diamine and external aldimine in this pathway were determined to be 25 and 4 s-1, respectively. There is also a slow interconversion between the protonated and deprotonated enzymes that has a pKa of approximately 8.0. Finally, the formation of the geminal diamine was determined to be Mg2+-dependent.

5-(Dimethoxymethyl)-2'-deoxyuridine: a novel gem diether nucleoside with anti-orthopoxvirus activity

To provide potential new leads for the treatment of orthopoxvirus infections, the 5-position of the pyrimidine nucleosides have been modified with a gem diether moiety to yield the following new nucleosides: 5-(dimethoxymethyl)-2'-deoxyuridine (2b), 5-(diethoxymethyl)-2'-deoxyuridine (3b), 5-formyl-2'-deoxyuridine ethylene acetal (4b), and 5-formyl-2'-deoxyuridine propylene acetal (5b). These were evaluated in human foreskin fibroblast cells challenged with the vaccinia virus or cowpox virus. Of the four gem diether nucleosides, only the dimethyl gem diether congener showed significant antiviral activity against both viruses. This antiviral activity did not appear to be related to the decomposition to the 5-formyl-2'-deoxyuridine, which was itself devoid of anti-orthopoxvirus activity in these assays. Moreover, at the pH of the in vitro assays, 2b was very stable with a decomposition (to aldehyde) half-life of >15 d. The anti-orthopoxvirus activity of pyrimidine may be favored by the introduction of hydrophilic moieties to the 5-position side chain.

Detection ofBacillussubtilisSpores Using Peptide-Functionalized Cantilever Arrays

We move beyond antibody-antigen binding systems and demonstrate that short peptide ligands can be used to efficiently capture Bacillus subtilis (a simulant of Bacillus anthracis) spores in liquids. On an eight-cantilever array chip, four cantilevers were coated with binding peptide (NHFLPKV-GGGC) and the other four were coated with control peptide (LFNKHVP-GGGC) for reagentless detection of whole B. subtilis spores in liquids. The peptide-ligand-functionalized microcantilever chip was mounted onto a fluid cell filled with a B. subtilis spore suspension for approximately 40 min; a 40 nm net differential deflection was observed. Fifth-mode resonant frequency measurements were also performed before and after dipping microcantilever arrays into a static B. subtilis solution showing a substantial decrease in frequency for binding-peptide-coated microcantilevers as compared to that for control peptide cantilevers. Further confirmation was obtained by subsequent examination of the microcantilever arrays under a dark-field microscope. Applications of this technology will serve as a platform for the detection of pathogenic organisms including biowarfare agents.

Nucleic acid test screening of blood donors for orthopoxviruses can potentially prevent dispersion of viral agents in case of bioterrorism

BACKGROUND

Microbiologic agents such as variola virus (VAR) are very attractive for terrorism. As a result of international collaboration under the WHO eradication campaign, smallpox was declared eradicated in 1980. Therefore, the immunization programs were discontinued worldwide. Because most people are now immunologically naive, VAR is considered to be a potential threat agent or bioterrorist weapon. Real-time polymerase chain reaction (PCR) followed by melting analysis was developed for fast and safe analysis and allows differentiation of VAR from other orthopoxviruses (OPVs) like vaccinia or camelpox virus.

STUDY DESIGN AND METHODS

A RealArt Orthopox LC PCR kit (Artus GmbH) was used to amplify OPV sequences from blood donor samples. A total of 31,500 blood donor samples were tested in minipools of up to 96 samples. To evaluate the sensitivity of the assay, routine donor minipools (90 +/- 6 samples per pool) were spiked with vaccinia virus used as positive control.

RESULTS

Specificity was 100 percent because none of 31,500 blood donors was positive for the presence OPV. The detection limit of the assay was 10.6 copies per PCR procedure. Therefore, a sensitivity of 1590 copies per mL was calculated. Overall, 0.28 percent of test results had to be considered invalid owing to negative internal controls.

CONCLUSION

The RealArt Orthopox LC PCR kit enables reliable detection of OPV DNA in viremic blood donor samples, even at the beginning of the disease when patients present minor clinical symptoms, and could be implemented in our routine screening procedure immediately. Thus, the assay could potentially help to prevent dispersion of viral agents by blood transfusion in case of bioterrorism.