Anthrax Research Articles

Rapid Capsular Antigen Immunoassay for Diagnosis of Inhalational Anthrax: Preclinical Studies and Evaluation in a Nonhuman Primate Model.

ABSTRACTInhalational anthrax is a fatal infectious disease. Rapid and effective treatment is critically dependent on early and accurate diagnosis. Blood culture followed by identification and confirmation may take days to provide clinically relevant information. In contrast, immunoassay for a shed antigen, the capsular polypeptide gamma-d-polyglutamate (γDPGA), can provide rapid results at the point of care. In this study, a lateral flow immunoassay for γDPGA was evaluated in a robust nonhuman primate model of inhalational anthrax. The results showed that the time to a positive result with the rapid test using either serum or blood as a clinical specimen was similar to the time after infection when a blood culture became positive. In vitro testing showed that the test was equally sensitive with cultures of the three major clades of Bacillus anthracis. Cultures from other Bacillus spp. that are known to produce γDPGA also produced positive results. The test was negative with human sera from 200 normal subjects and 45 subjects with culture-confirmed nonanthrax bacterial or fungal sepsis. Taken together, the results showed that immunoassay for γDPGA is an effective surrogate for blood culture in a relevant cynomolgus monkey model of inhalational anthrax. The test would be a valuable aid in early diagnosis of anthrax, which is critical for rapid intervention and a positive outcome. Use of the test could facilitate triage of patients with signs and symptoms of anthrax in a mass-exposure incident and in low-resource settings where laboratory resources are not readily available.

Automatic microscopic diagnosis of diseases using an improved UNet++ architecture

Anthrax is a severe infectious disease caused by the Bacillus anthracis bacterium. This paper aims to design and implement a fast and reliable system based on microscopic image processing of patient tissue samples for the automatic diagnosis of anthrax and other tissues diseases, metastasis detection, patient prognosis, etc. An improved UNet++ architecture is proposed to segment microscopic images of patient tissue samples. The proposed model combines multi-scale features by adding skip connections in two paths; the forward path from the encoder to the decoder and the decoder path to the output. These new connections improve the performance of the UNet++. Integration of the squeeze and excitation-inception blocks in the new skip connections provides the network with features at different scales with different kernel sizes. Several convolutional networks are used as the backbone to extract powerful representations in the encoder section. The use of batch normalization, dropout technique, and LRelu activation function in this model accelerates convergence and increases the generalization power of the model. To overcome the problem of data imbalance of different classes, a weighted hybrid loss function is proposed, which further improved segmentation efficiency. The semantic segmentation results are converted to the instance segmentation using the marker-based watershed algorithm. Experimental results show that despite many challenges of microscopic image analysis, the proposed model is a reliable system for the automatic diagnosis of anthrax and other tissues diseases. It produces better results than state-of-the-art architectures.

Climate stress impacts on livestock health: Implications for farming livelihoods and animal disease in Karnataka, India

AbstractUnderstanding the impact of climate change on livestock health is critical to safeguarding global food supplies, economies, and farming livelihoods. We evidence, through exploration of secondary data informed by a rapid ethnographic assessment of farming livelihoods in Karnataka, India, that both precipitation and vapour pressure are key climate variables relating to outbreaks of haemorrhagic septicaemia (HS), anthrax (AX), and black quarter (BQ) across the Indian state of Karnataka. We then developed a risk classification tool that assesses how disease risk varies in Karnataka at present and in possible future scenarios. Temperature and maximum temperature are negatively correlated with HS, AX, and BQ, indicating that regions experiencing a cool (but still hot) climate with increasingly wetter, more humid conditions are at high risk of future outbreaks. Principal component analyses revealed the southwest India monsoon and winter periods to be the most strongly correlated with HS, AX, and BQ outbreaks. Vapour pressure, a proxy for humidity, has a positive relationship with these specific livestock diseases. Certain environmental conditions increase the incidence of some bacterial diseases and conditions that mimic their symptoms, and thus also risk driving up the use of antibiotics and the emergence of antimicrobial resistance (AMR) in regions under stress. This methodology can be replicated to investigate other diseases and regions, as long as the climate and epidemiological data cover similar time periods. This evidence highlights the need for greater synergies between climate change and One Health research and policy.One Health Impact StatementWe have taken a transdisciplinary approach, which expands out of One Health to include climate science and participatory research with farmers and livestock industry consultants, to investigate the relationship between factors related to climate (surface temperatures, rainfall, humidity) and outbreaks of livestock-related bacterial diseases. This is especially relevant to the One Health approach as it attempts to integrate findings between not only the science of disease but also the science of climate change as a driver of disease, and address problems that could arise within the public and private sectors (local farming, livestock health, government policy etc.). Providing spatial context to climate-associated disease risk across the Indian state of Karnataka will benefit: local farmers who may already be practising, or are transitioning to, more intensive livestock farming; policymakers; and private sector companies who are planning for future investments. Such expansion needs to be undertaken with full awareness of potentially heightened disease risk. Our transdisciplinary approach is borne from the observations of famers’ lived experiences of challenges to their livelihoods and facilitates the use of climate datasets that may not have been primarily collected for, or used by, disease-related studies to map long-term epidemiological risk. This demonstrates the pragmatic impact that such transdisciplinary projects can have, by providing interpretations of observed risks to animal health (highlighted by social scientists during engagement with practitioner communities) that Earth Scientists were then able to quantify, proving links that would otherwise not have been evidenced. The use of disease data sourced from local institutions, including the Government of India and research laboratories, can inform plans for the application of pragmatic solutions to local challenges by local farmers who are primarily impacted by the challenges highlighted in the research.

'A remedy for this dread disease': Achille Sclavo, anthrax and serum therapy in early twentieth-century Britain.

In the years around 1900 one of the most significant practical consequences of new styles of bacteriological thought and practice was the development of preventive vaccines and therapeutic sera. Historical scholarship has highlighted how approaches rooted in the laboratory methods of Robert Koch, Louis Pasteur and their collaborators were transformed in local contexts and applied in diverse ways to enable more effective disease identification, prevention and treatment. Amongst these, the anti-anthrax serum developed by the Italian physician Achille Sclavo (1861-1930) has received little to no attention from historians. This article positions Sclavo's serum as a neglected but significant presence in British microbiology, which achieved widespread uptake amidst a wave of optimism, despite prolonged uncertainty about its mechanism of action and dosage. After being introduced to Britain in 1904 by the enterprising first medical inspector of factories Thomas Morison Legge, within a matter of months the serum became regarded by medical practitioners as an effective treatment of cutaneous anthrax, though access to 'fresh' serum and the necessary speedy diagnosis remained problematic. Like the disease anthrax itself, discussion of 'Sclavo's serum' was out of all proportion to the relatively low number of cases, reflecting a deep-seated fascination with the wider possibilities afforded by effective serum therapy.

Welder's Anthrax: A Review of an Occupational Disease.

Since 1997, nine cases of severe pneumonia, caused by species within the B. cereus group and with a presentation similar to that of inhalation anthrax, were reported in seemingly immunocompetent metalworkers, with most being welders. In seven of the cases, isolates were found to harbor a plasmid similar to the B. anthracis pXO1 that encodes anthrax toxins. In this paper, we review the literature on the B. cereus group spp. pneumonia among welders and other metalworkers, which we term welder’s anthrax. We describe the epidemiology, including more information on two cases of welder’s anthrax in 2020. We also describe the health risks associated with welding, potential mechanisms of infection and pathological damage, prevention measures according to the hierarchy of controls, and clinical and public health considerations. Considering occupational risk factors and controlling exposure to welding fumes and gases among workers, according to the hierarchy of controls, should help prevent disease transmission in the workplace.

Reoccurring Bovine Anthrax in Germany on the Same Pasture after 12 Years.

ABSTRACTThe zoonotic disease anthrax, caused by the endospore-forming bacterium Bacillus anthracis, is very rare in Germany. In the state of Bavaria, the last case occurred in July of 2009, resulting in four dead cows. In August of 2021, the disease reemerged after heavy rains, killing one gestating cow. Notably, both outbreaks affected the same pasture, suggesting a close epidemiological connection. B. anthracis could be grown from blood culture, and the presence of both virulence plasmids (pXO1 and pXO2) was confirmed by PCR. Also, recently developed diagnostic tools enabled rapid detection of B. anthracis cells and nucleic acids directly in clinical samples. The complete genome of the strain isolated from blood, designated BF-5, was DNA sequenced and phylogenetically grouped within the B.Br.CNEVA clade, which is typical for European B. anthracis strains. The genome was almost identical to BF-1, the isolate from 2009, separated only by three single nucleotide polymorphisms (SNPs) on the chromosome, one on plasmid pXO2 and three indel regions. Further, B. anthracis DNA was detected by PCR from soil samples taken from spots in the pasture where the cow had fallen. New tools based on phage receptor-binding proteins enabled the microscopic detection and isolation of B. anthracis directly from soil samples. These environmental isolates were genotyped and found to be identical to BF-5 in terms of SNPs. Therefore, it seems that the BF-5 genotype is currently the prevalent one at the affected premises. The area contaminated by the cadaver was subsequently disinfected with formaldehyde.

First PCR Confirmed anthrax outbreaks in Ethiopia-Amhara region, 2018-2019.

BackgroundAnthrax is a disease that affects humans and animals. In Ethiopia, anthrax is a reportable disease and assumed to be endemic, although laboratory confirmation has not been routinely performed until recently. We describe the findings from the investigation of two outbreaks in Amhara region.MethodsFollowing reports of suspected outbreaks in Wag Hamra zone (Outbreak 1) and South Gondar zone (Outbreak 2), multi-sectoral teams involving both animal and public health officials were deployed to investigate and establish control programs. A suspect case was defined as: sudden death with rapid bloating or bleeding from orifice(s) with unclotted blood (animals); and signs compatible with cutaneous, ingestion, or inhalation anthrax ≤7 days after exposure to a suspect animal (humans). Suspect human cases were interviewed using a standard questionnaire. Samples were collected from humans with suspected anthrax (Outbreak 1 and Outbreak 2) as well as dried meat of suspect animal cases (Outbreak 2). A case was confirmed if a positive test was returned using real-time polymerase chain reaction (qPCR).ResultsIn Outbreak 1, a total of 49 cows died due to suspected anthrax and 22 humans developed symptoms consistent with cutaneous anthrax (40% attack rate), two of whom died due to suspected ingestion anthrax. Three people were confirmed to have anthrax by qPCR. In Outbreak 2, anthrax was suspected to have caused the deaths of two livestock animals and one human. Subsequent investigation revealed 18 suspected cases of cutaneous anthrax in humans (27% attack rate). None of the 12 human samples collected tested positive, however, a swab taken from the dried meat of one animal case (goat) was positive by qPCR.ConclusionWe report the first qPCR-confirmed outbreaks of anthrax in Ethiopia. Both outbreaks were controlled through active case finding, carcass management, ring vaccination of livestock, training of health professionals and outreach with livestock owners. Human and animal health authorities should work together using a One Health approach to improve case reporting and vaccine coverage.

Dual-ligand two-dimensional Europium-organic gels nanosheets for ratiometric fluorescence detecting anthrax spore biomarker

A series of novel dual-ligand two-dimensional Europium-organic gels (2D Eu-MOGs) nanosheets, namely, 2D Eu-PB MOG 1, 2D Eu-PB MOG 2 and 2D Eu-PB MOG 3 nanosheets, were constructed via simply blending the reaction mixture of Eu salts, 1,10-phenanthroline-2, 9-dicarboxylic acid (Phen), and 2-aminoterephthalic acid (BDC-NH2) at room temperature. 2D Eu-PB MOGs nanosheets had excellent dipicolinic acid (DPA) sensing properties exhibiting dual emission originated from BDC-NH2 and Eu3+ at 417 and 610 nm. An energy transfer between Eu3+ nodes and DPA in 2D Eu-PB MOGs nanosheets enhanced the red fluorescence at 610 nm while the blue fluorescence from BDC-NH2 kept stable, resulting in ratiometric fluorescence response to DPA. Besides, the introduction of DPA could replace coordinated H2O in 2D Eu-PB MOGs nanosheets minimizing the nonradiative quenching of Eu3+, which greatly improved the sensitivity. As a novel ratiometric fluorescence probe, 2D Eu-PB MOGs nanosheets exhibited a good linear response toward anthrax spores from 2.1 × 104 CFU·mL−1 to 1.26 × 105 CFU·mL−1. The present study not only proposed an efficient method for the construction of 2D MOGs but also made a new way for the design of fluorescence probe with remarkable sensing property.

Aerosolized Intratracheal Inoculation of Recombinant Protective Antigen (rPA) Vaccine Provides Protection Against Inhalational Anthrax in B10.D2-Hc0 Mice.

Anthrax caused by Bacillus anthracis is a fatal zoonotic disease with a high lethality and poor prognosis. Inhalational anthrax is the most severe of the three forms of anthrax. The currently licensed commercial human anthrax vaccines require a complex immunization procedure for efficacy and have side effects that limit its use in emergent situations. Thus, development of a better anthrax vaccine is necessary. In this study, we evaluate the potency and efficacy of aerosolized intratracheal (i.t.) inoculation with recombinant protective antigen (rPA) subunit vaccines against aerosolized B. anthracis Pasteur II spores (an attenuated strain) challenge in a B10.D2-Hc0 mouse (deficient in complement component C5) model. Immunization of rPA in liquid, powder or powder reconstituted formulations via i.t. route conferred 100% protection against a 20× LD50 aerosolized Pasteur II spore challenge in mice, compared with only 50% of subcutaneous (s.c.) injection with liquid rPA. Consistently, i.t. inoculation of rPA vaccines induced a higher lethal toxin (LeTx) neutralizing antibody titer, a stronger lung mucosal immune response and a greater cellular immune response than s.c. injection. Our results demonstrate that immunization with rPA dry powder vaccine via i.t. route may provide a stable and effective strategy to improve currently available anthrax vaccines and B10.D2-Hc0 mice challenged with B. anthracis attenuated strains might be an alternative model for anthrax vaccine candidate screening.

Assessment of socio-behavioural correlates and risk perceptions regarding anthrax disease in tribal communities of Odisha, Eastern India

BackgroundThis study is a baseline survey to assess the knowledge, attitude and practices with regards to the anthrax disease among the communities before demonstrating a One Health approach for elimination of human anthrax in an endemic district of Odisha. A total of 2670 respondents from 112 villages of 14 blocks were interviewed for the study using a structured questionnaire by multi-stage sampling method. Descriptive statistics were reported and logistic regression was performed to estimate the relationship between the variables and knowledge of anthrax.ResultOut of 2670 participants in the study, 76.25% were male and about half were illiterate. Most of the respondents (54.19%) were involved in agriculture as an occupation. 71% of the respondents had livestock in their houses and farming was the main purpose for keeping the livestock. Only one-fifth of the respondents (20.26%) knew about anthrax and a majority of them have come across the disease during community outbreaks. Almost 25.9% of livestock owners had knowledge about vaccination against anthrax disease although 83.4% of the livestock owners disposed the animal carcass by burial method.ConclusionThe study findings indicated that the community members had poor knowledge of cause, symptoms, transmission and prevention of anthrax disease which may be improved by a One Health approach.

Luminescent β-diketonate coordinated europium(III) sensor for rapid and sensitive detection of Bacillus Anthracis biomarker

The hazardous B. Anthracis are harmful pathogens causes anthrax could be potentially used as biothreat agents or bioweapons and have severe consequences to public health. These bacterial endospores contain dipicolinic acid (DPA) as calcium dipicolinate (CaDPA) as a primary cell wall constituent (1 M, 1015 molecules/spore). The anthrax attacks in USA by shipping spores in postal mails have triggered the hunt for a simple, rapid, sensitive, and selective detection of Bacillus Anthracis spores. Therefore, a fast and sensitive sensing platform for anthrax spores is critical to contain such biothreats and outbreaks of infection. Herein, we intend to develop a sensitive and selective optical detection strategy for anthrax spore biomarker based on DPA-sensitized lanthanide luminescence. The anionic hard DPA2− strongly binds with hard Ln3+ forming thermodynamically stable complex and sensitizing unique LnIII time-resolved luminescence originated from f-f transitions with a high S/N ratio. Here, we employed and repurposed a simple luminescent EuIII complex: [Eu(TTA)3(H2O)2] (1) (TTA: 3-thenoyltrifluoroacetonate) for the detection of the DPA2− biomarker. Complex 1, when titrated with DPA, displayed instant Switch-ON optical response by 10-fold enhancement in the time-resolved luminescence (TRL) intensity of the 5D0→7F2 transition, which is sensitive to the changes in the symmetry of the EuIII primary coordination sphere. Upon binding with DPA, we also observed shifting of the excitation wavelength (λex) from ∼345 nm to 275 nm in the presence of ∼3.0 mol equivalent of dipicolinic acid. After stoichiometric reaction with DPA, the resulting complex has a long-lived, highly stable excited state of the EuIII ion with a lifetime of 2100 μs in solution compared to only 260 μs for the original probe. We proposed possible displacement of the TTA− and H2O from the primary coordination sphere of the EuIII ion by potent chelating antenna ligand DPA2−. This reaction results in the formation of nine-coordinated [Eu(DPA)3]3- complex in solution confirmed by ESI-MS analysis. The luminescence response of the complex 1 is found highly selective for DPA in the presence of various interfering carboxylic acids and quantitatively able to detect up to 1.20 μM.

Epidemiological Investigation of an Inhalational Anthrax Patient Traveling for Medical Treatment in Beijing Municipality, China, August 2021.

What is already known about this topic?Inhalational anthrax, also known as pulmonary anthrax, is an infectious disease caused by Bacillus anthracis. The patients are usually infected by inhaling aerosolized B. anthracis spores from dead animals or animal products. Compared to cutaneous anthrax, inhalational anthrax is rare and deadly and few cases in China were reported. What is added by this report?This report covers all information of clinical features, laboratory testing, and epidemiological characteristics as well as exposure history of a recent primary inhalational anthrax patient who was seeking medical treatment in Beijing Municipality in August 2021. New laboratory techniques, including second-generation sequencing, polymerase chain reaction, and rapid test for serum antibody, played an important role in the process.What are the implications for public health practice?The information provided in this report, including the correct sample type, epidemiological investigation details, and application of the new diagnostic criteria of anthrax, could assist public health professionals in dealing with anthrax epidemics.

The impact of the COVID-19 pandemic on the incidence and mortality of zoonotic diseases in China.

BackgroundIt has been reported that strict non-pharmaceutical measures can significantly reduce the incidence and mortality of respiratory and intestinal infectious diseases during the COVID-19 pandemic, but there are limited reports on the impact in terms of the rates of zoonotic diseases.MethodsWe extracted the incidence and mortality data of eight notifiable infectious zoonotic diseases from the website of the National Health Commission of the People’s Republic of China for the period of January 2015 to April 2021.ResultsFirst, the overall incidence of zoonotic diseases decreased from 0.3714 per 100 000 in 2015–2019 to 0.2756 in 2020 (25.79% reduction, p<0.001); however, a dramatic increase in activity was seen in 2021 compared with 2020 (0.4478 per 100 000 in 2021, 62.47% increase, p<0.001). Anthrax, brucellosis, leptospirosis and hydatid disease exhibited significant upward trends in 2021. Second, analysed further by stages, the monthly incidence in the routine stage (from May to December 2020) was much higher than that in the emergency stage of the COVID-19 (from January to April 2020) (55.33% increase, p<0.001). We also found that the monthly observed incidence was significantly lower than the predicted incidence of a 10.29% reduction in the emergency stage. Third, no differences were seen in mortality between 2021 and 2020, while a significant decline was found in 2020 compared with the previous 5 years (72.70%, p<0.001).ConclusionsStrict containment and feasible suppression strategies during the 2020 period of the COVID-19 pandemic had positive impacts on the overall incidence of zoonotic diseases in China. However, anthrax, brucellosis, leptospirosis and hydatid diseases might increase with the relaxation of non-pharmacological interventions in 2021.

ПЕРСПЕКТИВНЫЕ НАУЧНЫЕ НАПРАВЛЕНИЯ ФУНДАМЕНТАЛЬНЫХ ИССЛЕДОВАНИЙ В ОБЛАСТИ ВЕТЕРИНАРНОЙ САНИТАРИИ

The complex and constantly changing epizootic situation for a number of especially dangerous and socially significant infectious animal diseases, such as anthrax, foot and mouth disease, african swine fever, avian influenza, etc., puts forward important tasks for veterinary and sanitary science aimed at ensuring food, biological and environmental safety of the country, including bioterrorism and man-made disasters. The article presents the directions of fundamental research work and organizational measures, the implementation of which is advisable to solve important strategic issues to ensure the protection of animal and human health from especially dangerous diseases and food-borne diseases, biological, ecological and food security of our country.

A luminescent terbium(iii) probe as an efficient ‘Turn-ON’ sensor for dipicolinic acid, a Bacillus Anthracis biomarker

This work drives the potential of lanthanide luminescence in the quantification and detection of the B. Anthracis bacterial spore by targeting dipicolinic acid (DPA), a principal component of anthrax spores.

Modeling of Anthrax Disease via Efficient Computing Techniques

Computer methods have a significant role in the scientific literature. Nowadays, development in computational methods for solving highly complex and nonlinear systems is a hot issue in different disciplines like engineering, physics, biology, and many more. Anthrax is primarily a zoonotic disease in herbivores caused by a bacterium called Bacillus anthracis. Humans generally acquire the disease directly or indirectly from infected animals, or through occupational exposure to infected or contaminated animal products. The outbreak of human anthrax is reported in the Eastern Mediterranean regions like Pakistan, Iran, Iraq, Afghanistan, Morocco, and Sudan. Almost ninety-five percent chances are the transmission of the bacteria from forming spores by the World Health Organization (WHO). The modeling of an anthrax disease is based on the four compartments along with two humans (susceptible and infected) and others are dead bodies and sporing agents. The mathematical analysis is studied along with the fundamental properties of deterministic modeling. The stability of the model along with equilibria is studied rigorously. The authentication of analytical results is examined through well-known computer methods like Euler, Runge Kutta, and Non-standard finite difference (NSFD) along with the feasible properties (positivity, boundedness, and dynamical consistency) of the model. In the end, comparison analysis of algorithms shows the effectiveness of the methods.

COMPARISON OF PROPOLIS EFFECTS ON TUMOR NECROSIS FACTOR ALPHA AND MALONDIALDEHYDE BETWEEN INHALATION AND CUTANEOUS ANTHRAX ANIMAL MODELS.

Background:Inflammatory response and oxidative stress can be found in anthrax characterized by increased level of serum Tumor Necrosis Factor Alpha (TNF-α) and Malondialdehyde (MDA). The use of antibiotics in anthrax has been known to cause some disturbing side-effects, such as allergic reaction, nausea, vomiting, and antibiotic resistance. Thus, ethanolic extract of propolis (EEP) might be the alternative regimen, due to its anti-inflammatory and antioxidant properties. This study aimed to compare the effects of ethanolic extract of propolis (EEP) on TNF-α and MDA between the inhalation and cutaneous anthrax animal model.Materials and Methods:This was an experimental study with a post-test-only control group design on 40 samples of Rattus norvegicus. Samples were randomized into 5 groups: control, inhalation anthrax model, inhalation anthrax model + EEP, cutaneous anthrax model, and cutaneous anthrax model + EEP. After 14 days, the level of TNF-α and MDA were measured. To compare the data, we used the ANOVA test continued by the post-hoc Turkey test.Results:The results obtained showed that the level of TNF-α and MDA between the inhalation and cutaneous anthrax animal models treated with EEP were statistically different (p < 0.05). The P5 group showed the lowest level of TNF-α (6.822 ± 0.383 pg/ml) and MDA (2.717 ± 0.383 nmol/ml).Conclusion:EEP has a better effect on reducing TNF-α and MDA in cutaneous anthrax animal models compared to the inhalation anthrax animal model.

Metabolic profiling reveals nutrient preferences during carbon utilization in Bacillus species

The genus Bacillus includes species with diverse natural histories, including free-living nonpathogenic heterotrophs such as B. subtilis and host-dependent pathogens such as B. anthracis (the etiological agent of the disease anthrax) and B. cereus, a cause of food poisoning. Although highly similar genotypically, the ecological niches of these three species are mutually exclusive, which raises the untested hypothesis that their metabolism has speciated along a nutritional tract. Here, we developed a pipeline for quantitative total assessment of the use of diverse sources of carbon for general metabolism to better appreciate the “culinary preferences” of three distinct Bacillus species, as well as related Staphylococcus aureus. We show that each species has widely varying metabolic ability to utilize diverse sources of carbon that correlated to their ecological niches. This approach was applied to the growth and survival of B. anthracis in a blood-like environment and find metabolism shifts from sugar to amino acids as the preferred source of energy. Finally, various nutrients in broth and host-like environments are identified that may promote or interfere with bacterial metabolism during infection.

Multiplexed, High-Sensitivity Measurements of Antibody Affinity Using Interferometric Reflectance Imaging Sensor.

Anthrax lethal factor (LF) is one of the enzymatic components of the anthrax toxin responsible for the pathogenic responses of the anthrax disease. The ability to screen multiplexed ligands against LF and subsequently estimate the effective kinetic rates ( and ) and complementary binding behavior provides critical information useful in diagnostic and therapeutic development for anthrax. Tools such as biolayer interferometry (BLI) and surface plasmon resonance imaging (SPRi) have been developed for this purpose; however, these tools suffer from limitations such as signal jumps when the solution in the chamber is switched or low sensitivity. Here, we present multiplexed antibody affinity measurements obtained by the interferometric reflectance imaging sensor (IRIS), a highly sensitive, label-free optical biosensor, whose stability, simplicity, and imaging modality overcomes many of the limitations of other multiplexed methods. We compare the multiplexed binding results obtained with the IRIS system using two ligands targeting the anthrax lethal factor (LF) against previously published results obtained with more traditional surface plasmon resonance (SPR), which showed consistent results, as well as kinetic information previously unattainable with SPR. Additional exemplary data demonstrating multiplexed binding and the corresponding complementary binding to sequentially injected ligands provides an additional layer of information immediately useful to the researcher.

Multiple stages of evolutionary change in anthrax toxin receptor expression in humans

The advent of animal husbandry and hunting increased human exposure to zoonotic pathogens. To understand how a zoonotic disease may have influenced human evolution, we study changes in human expression of anthrax toxin receptor 2 (ANTXR2), which encodes a cell surface protein necessary for Bacillus anthracis virulence toxins to cause anthrax disease. In immune cells, ANTXR2 is 8-fold down-regulated in all available human samples compared to non-human primates, indicating regulatory changes early in the evolution of modern humans. We also observe multiple genetic signatures consistent with recent positive selection driving a European-specific decrease in ANTXR2 expression in multiple tissues affected by anthrax toxins. Our observations fit a model in which humans adapted to anthrax disease following early ecological changes associated with hunting and scavenging, as well as a second period of adaptation after the rise of modern agriculture.