Efficacy assessment of a triple anthrax chimeric antigen as a vaccine candidate in guinea pigs: challenge test with Bacillus anthracis 17 JB strain spores.

CONTEXT: Bacillus anthracis secretes a tripartite toxin comprising protective antigen (PA), edema factor (EF), and lethal factor (LF). The human anthrax vaccine is mainly composed of the anthrax protective antigen (PA). Considerable efforts are being directed towards improving the efficacy of vaccines because the use of commercial anthrax vaccines (human/veterinary) is associated with several limitations. OBJECTIVE: In this study, a triple chimeric antigen referred to as ELP (gene accession no: MT590758) comprising highly immunogenic domains of PA, LF, and EF was designed, constructed, and assessed for the immunization capacity against anthrax in a guinea pig model. MATERIALS AND METHODS: Immunization was carried out considering antigen titration and immunization protocol. The immunoprotective efficacy of the ELP was evaluated in guinea pigs and compared with the potency of veterinary anthrax vaccine using a challenge test with B. anthracis 17JB strain spores. RESULTS: The results demonstrated that the ELP antigen induced strong humoral responses. The T-cell response of the ELP was found to be similar to PA, and showed that the ELP could protect 100%, 100%, 100%, 80% and 60% of the animals from 50, 70, 90, 100 and 120 times the minimum lethal dose (MLD, equal 5 × 105 spore/ml), respectively, which killed control animals within 48 h. DISCUSSION AND CONCLUSIONS: It is concluded that the ELP antigen has the necessary requirement for proper immunization against anthrax and it can be used to develop an effective recombinant vaccine candidate against anthrax.

Assessment of knowledge, attitudes and practices towards anthrax in Narok County, Southern Kenya.

INTRODUCTION: anthrax is endemic in some parts of Kenya causing mortalities in livestock and morbidity in humans. On January 20th, 2018, news media reported suspected anthrax in a remote southern Kenyan village after villagers became ill following consumption of meat from a dead cow that was confirmed, by microscopy, to have died of anthrax. We assessed community knowledge, attitude and practices (KAP) to identify intervention gaps for anthrax prevention. METHODS: we conducted a KAP survey in randomly selected households (HHs) in villages from selected wards. Using multi-stage sampling approach, we administered structured questionnaire to persons aged ≥15 years to collect KAP information from February 11th-21st, 2018. From a set of questions for KAP, we scored participants' response as "1" for a correct response and "0" for an incorrect response. Univariate analysis and Chi-square tests were performed to explore determinants of KAP. Concurrently, we gathered qualitative data using interview guides for thematic areas on anthrax KAP from key informant interviews and focus group discussions. Qualitative data were transcribed in Ms Word and analyzed along themes by content analysis. RESULTS: among 334 respondents: 187/334 (56%) were male; mean age, 40.7±13.6 years; 331/334 (99.1%) had heard of anthrax and 304/331 (91.8%) knew anthrax to be zoonotic. Transmission was considered to be through eating dead-carcasses by 273/331 (82.5%) and through contact with infected tissue by 213/331 (64.4%). About 59% (194/329) regularly vaccinated their livestock against anthrax, 53.0% (174/328) had slaughtered or skinned a dead-animal and 59.5% (195/328) practiced home slaughter while 52.9% (172/325) treated sick-animals by themselves. Sex (p≤0.001), age (p=0.007) and livestock-rearing years (p≤0.001) were significantly associated with knowledge and practice. CONCLUSION: there were differences in knowledge and practices towards anthrax by age-group and sex. Enhanced public health education and targeted interventions by relevant government agencies is recommended.

Update From the Advisory Committee on Immunization Practices.

The Advisory Committee on Immunization Practices (ACIP), a group of medical and public health experts, meets 3 times per year to develop recommendations for vaccine use in the United States. There are 15 voting members, and their terms are for 4 years. ACIP members and Centers for Disease Control and Prevention staff discuss the epidemiology of vaccine-preventable diseases and vaccine research, effectiveness, safety data, and clinical trial results. Representatives from the American Academy of Pediatrics (including D. W. K.) and the Pediatric Infectious Diseases Society are present as liaisons to the ACIP. In the February 2018 meeting, important votes on the use of influenza vaccine and hepatitis vaccines were held, and updates on human papillomavirus, meningococcal, and anthrax vaccines, among others, were provided.

Changing livestock vaccination policy alters the epidemiology of human anthrax, Georgia, 2000-2013.

Anthrax is a widely spread zoonotic disease found on nearly every continent. To control the disease in humans and animals, annual livestock vaccination is recommended. However, in 2007, the country of Georgia ended its policy of compulsory annual livestock anthrax vaccination. Our objective was to assess how the epidemiology of human anthrax has evolved from 2000-2013 in Georgia, in the wake of this cessation. We used passive surveillance data on epidemiological surveys of human anthrax case patients. Risk factors and rates of self-reported sources of infection were compared, before and after the change in livestock vaccination policy. We mapped ethnicity-adjusted incidence during the two periods and assessed changes in the spatial pattern of risk. The overall risk of human anthrax increased >5-fold, from 0.7 cases per 100,000 in 2000 to 3.7 cases per 100,000 by 2013. Ethnic disparities in risk became pronounced; from 2000 to 2013, incidence increased >60-fold in Azerbaijanis from 0.35 to 21.1 cases/100,000 Azerbaijanis compared to 0.61 to 1.9 cases/100,000 among ethnic Georgians. Food-borne exposures from purchasing meat increased from 11% in 2000-2006 to 21% in 2007-2013. Spatial analyses revealed a shift from a random pattern of reporting pre-policy change to clustering among district municipalities following the change in policy. Our findings indicate there were unintended human health consequences associated with changing livestock vaccination policy. Following a reduction in the immunizations administered, there was a major shift in the epidemiology of human anthrax in Georgia. Current infection risk is now highest among ethnic minorities. Increased reporting among individuals uncharacteristically at risk for anthrax from foodborne exposures suggests spillover from modes of agricultural production. Given the importance of human-livestock health linkages, careful evaluations of policy need to be undertaken before changes to animal vaccination are made.

Quantitative anti-PA IgG ELISA; assessment and comparability with the anthrax toxin neutralization assay in goats.

BACKGROUND: Presently, few data exist on the level and duration of anti-protective antigen (PA) IgG in vaccinated livestock. Various adaptation of enzyme-linked immunosorbent assays (ELISAs) have been developed in studies to assess immune response following vaccination, albeit mostly in laboratory rodent models. The quantitative anti-anthrax IgG ELISA in this study describes a method of enumerating the concentration of anti-PA specific IgG present in sera of immunized goats, with the aid of an affinity-purified caprine polyclonal anti-anthrax PA-83 IgG standard. This was compared with the anthrax toxin neutralization assay (TNA) which measures a functional subset of toxin neutralizing anti-PA IgG. RESULTS: The measured concentrations obtained in the standard curve correlated with the known concentration at each dilution. Percentage recovery of the standard concentrations ranged from 89 to 98% (lower and upper asymptote respectively). Mean correlation coefficient (r2) of the standard curve was 0.998. Evaluation of the intra-assay coefficient of variation showed ranges of 0.23-16.90% and 0.40-12.46% for days 28 and 140 sera samples respectively, following vaccination. The mean inter-assay coefficient of variation for triplicate samples repeated on 5 different days was 18.53 and 12.17% for days 28 and 140 sera samples respectively. Spearman's rank correlation of log-transformed IgG concentrations and TNA titres showed strong positive correlation (rs = 0.942; p = 0.01). CONCLUSION: This study provides evidence that an indirect ELISA can be used for the quantification of anti-anthrax PA IgG in goats with the added advantage of using single dilutions to save time and resources. The use of such related immunoassays can serve as potential adjuncts to potency tests for Sterne and other vaccine types under development in ruminant species. This is the first report on the correlation of polyclonal anti-anthrax PA83 antibody with the TNA in goats.

Quantitative assessment of anthrax vaccine immunogenicity using the dried blood spot matrix.

The collection, processing and transportation to a testing laboratory of large numbers of clinical samples during an emergency response situation present significant cost and logistical issues. Blood and serum are common clinical samples for diagnosis of disease. Serum preparation requires significant on-site equipment and facilities for immediate processing and cold storage, and significant costs for cold-chain transport to testing facilities. The dried blood spot (DBS) matrix offers an alternative to serum for rapid and efficient sample collection with fewer on-site equipment requirements and considerably lower storage and transport costs. We have developed and validated assay methods for using DBS in the quantitative anti-protective antigen IgG enzyme-linked immunosorbent assay (ELISA), one of the primary assays for assessing immunogenicity of anthrax vaccine and for confirmatory diagnosis of Bacillus anthracis infection in humans. We have also developed and validated high-throughput data analysis software to facilitate data handling for large clinical trials and emergency response.

Cost-effectiveness comparison of response strategies to a large-scale anthrax attack on the chicago metropolitan area: impact of timing and surge capacity.

Rapid public health response to a large-scale anthrax attack would reduce overall morbidity and mortality. However, there is uncertainty about the optimal cost-effective response strategy based on timing of intervention, public health resources, and critical care facilities. We conducted a decision analytic study to compare response strategies to a theoretical large-scale anthrax attack on the Chicago metropolitan area beginning either Day 2 or Day 5 after the attack. These strategies correspond to the policy options set forth by the Anthrax Modeling Working Group for population-wide responses to a large-scale anthrax attack: (1) postattack antibiotic prophylaxis, (2) postattack antibiotic prophylaxis and vaccination, (3) preattack vaccination with postattack antibiotic prophylaxis, and (4) preattack vaccination with postattack antibiotic prophylaxis and vaccination. Outcomes were measured in costs, lives saved, quality-adjusted life-years (QALYs), and incremental cost-effectiveness ratios (ICERs). We estimated that postattack antibiotic prophylaxis of all 1,390,000 anthrax-exposed people beginning on Day 2 after attack would result in 205,835 infected victims, 35,049 fulminant victims, and 28,612 deaths. Only 6,437 (18.5%) of the fulminant victims could be saved with the existing critical care facilities in the Chicago metropolitan area. Mortality would increase to 69,136 if the response strategy began on Day 5. Including postattack vaccination with antibiotic prophylaxis of all exposed people reduces mortality and is cost-effective for both Day 2 (ICER=$182/QALY) and Day 5 (ICER=$1,088/QALY) response strategies. Increasing ICU bed availability significantly reduces mortality for all response strategies. We conclude that postattack antibiotic prophylaxis and vaccination of all exposed people is the optimal cost-effective response strategy for a large-scale anthrax attack. Our findings support the US government's plan to provide antibiotic prophylaxis and vaccination for all exposed people within 48 hours of the recognition of a large-scale anthrax attack. Future policies should consider expanding critical care capacity to allow for the rescue of more victims.

Disability among US Army Veterans vaccinated against anthrax.

CONTEXT: To protect troops against the use of anthrax as a biological weapon, the US Department of Defense began an anthrax vaccination program in 1998. 14 years after the inception of the vaccination program, there is no evidence suggesting vaccination against anthrax carries long-term health risks for Active Duty Soldiers. OBJECTIVE: To investigate the association between Anthrax Vaccine Adsorbed (AVA) received while on Active Duty and subsequent disability determined by the Veterans Benefits Administration. DESIGN, SETTING AND PARTICIPANTS: Case-control study nested in the cohort of all Active Duty personnel known to have separated from the US Army between December 1, 1997 and December 31, 2005. Cases were ≥10% disabled, determined either by the Army prior to separation (N=5846) or by the Veterans Benefits Administration (VBA) after separation (N=148,934). Controls (N=937,705) separated from the Army without disability, and were not receiving pensions from the VBA as of April 2007. Data were from the Total Army Injury and Health Outcomes Database and the VBA Compensation and Pension and Benefits database. MAIN OUTCOMES: Disability status (yes/no); for primary disability, percent disabled (≥10%, 20%, >20%) and type of disability. RESULTS: Vaccination against anthrax was four times more likely among disabled Veterans with hostile fire pay records (HFP, a surrogate for deployment). Vaccinated Soldiers with HFP had lower odds of disability separation from the Army 0.89 (0.80, 0.98); there was no association between vaccine and receiving Army disability benefits among those without HFP (OR=1.05, CI: 0.96, 1.14). Vaccination was negatively associated with receiving VA disability benefits for those with HFP (OR=0.66, CI: 0.65, 0.67), but there was little or no association between vaccine and receipt of VA disability benefits for those without HFP (OR=0.95, CI: 0.93, 0.97). CONCLUSIONS: Risk of disability separation from the Army and receipt of disability compensation from the VA were not increased in association with prior exposure to AVA. This study provides evidence that vaccination against anthrax is not associated with long term disability.

Producing, controlling, and stabilizing Pasteur's anthrax vaccine: creating a new industry and a health market.

When Pasteur and Chamberland hastily set up their small biological industry to meet the agricultural demand for the anthrax vaccine, their methods for preparation and production had not yet been stabilized. The process of learning how to standardize biological products was accelerated in 1882 when vaccination accidents required the revision of production norms as the first hypotheses on fixity, inalterability, and transportability of vaccines were invalidated and replaced by procedures for continuous monitoring of the calibration of vaccines and the renewal of vaccine strains. Initially, the incompleteness and ongoing development of production standards justified Pasteur's monopoly on the production of the anthrax vaccine under his immediate supervision. Later on, the Pasteur Institute maintained control of these standards in the framework of a commercial monopoly that it established on the veterinary vaccines first sent and then cultivated abroad by the Société de Vulgarisation du Vaccin Charbonneux Pasteur, founded in 1886.

U.S. military service members' perceptions of the Anthrax Vaccine Immunization Program.

This research identifies the perceptions of U.S. military service members regarding the Department of Defense Anthrax Vaccine Immunization Program (AVIP). The service members' perceptions were addressed in the dimensions of ethics, effectiveness, and safety, as well as the overall perceptions of the AVIP. The study, conducted in October 2004, randomly selected active duty service members from the uniformed services assigned to a Caribbean military base who participated in the AVIP during the period of 1998 to 2000. Their perceptions were measured with a survey instrument with 14 closed-ended, Likert-scale questions. The research demonstrated that a substantial number of service members disagreed with issues regarding the ethics, safety, and efficacy of the AVIP. We recommend enhanced training and education to increase understanding of the benefits of the AVIP.

Interlaboratory comparison of results of an anthrax lethal toxin neutralization assay for assessment of functional antibodies in multiple species.

The anthrax lethal toxin neutralization assay (TNA) will likely be used to correlate the protection offered by new anthrax vaccines in animal models to the immunogenicity that will be provided in humans. TNA data are being generated in several different laboratories to measure the immune responses in rabbits, nonhuman primates, and humans. In order to compare data among species and laboratories, a collaborative study was conducted in which 108 samples from the three species were analyzed in seven independent laboratories. Six of the seven laboratories had participated in an interlaboratory technology transfer of the TNA. Analysis of the titration curves generated by samples from each species indicated that the behaviors of the samples from all species were similar; the upper and lower asymptotes and the slopes of the curves were less than 30% divergent from those for human reference material. Dilutional linearity was consistent among samples from each species, with spike to effective dilution at 50% inhibition (ED(50)) slopes of less than 1.2 for all species. Agreement among the laboratories with consensus values was within 10% of the ED(50)s for all samples and within 7.5% of the quotients of the test sample ED(50) and the reference standard ED(50) (NF(50)s) for all samples. The relative standard deviations obtained when data from all laboratories and for all species were combined were 45% for the ED(50)s and 35% for the NF(50)s. These precision data suggest that the NF(50) readout may normalize the values generated by different laboratories. This study demonstrates that the TNA is a panspecies assay that can be performed in several different laboratories with a high degree of quantitative agreement and precision.

The anthrax vaccine and research: reactions from postal workers and public health professionals.

During the 2001 anthrax attacks, public health agencies faced operational and communication decisions about the use of antibiotic prophylaxis and the anthrax vaccine with affected groups, including postal workers. This communication occurred within an evolving situation with incomplete and uncertain data. Guidelines for prophylactic antibiotics changed several times, contributing to confusion and mistrust. At the end of 60 days of taking antibiotics, people were offered an additional 40 days' supply of antibiotics, with or without the anthrax vaccine, the former constituting an investigational new drug protocol. Using data from interviews and focus groups with 65 postal workers in 3 sites and structured interviews with 16 public health professionals, this article examines the challenges for public health professionals who were responsible for communication with postal workers about the vaccine. Multiple factors affected the response, including a lack of trust, risk perception, disagreement about the recommendation, and the controversy over the military's use of the vaccine. Some postal workers reacted with suspicion to the vaccine offer, believing that they were the subjects of research, and some African American workers specifically drew an analogy to the Tuskegee syphilis study. The consent forms required for the protocol heightened mistrust. Postal workers also had complex and ambivalent responses to additional research on their health. The anthrax attacks present us with an opportunity to understand the challenges of communication in the context of uncertain science and suggest key strategies that may improve communications about vaccines and other drugs authorized for experimental use in future public health emergencies.

[Assessment of immunity and allergy after vaccination with dry combined anthrax vaccine].

Study of humoral immune response and allergy in recipients of dry combined anthrax vaccine was performed. Immune response was assessed by antibody titers to protective antigen and by index of preventive properties of blood serum (PPS) of recipients. Relation of index of PPS and antibody titers in blood serum of the donors was established. Distribution of erythrocyte antigens in recipients of live dry and combined anthraxvaccines depending on blood group, Rh-factor, and age was studied. It has been shown that 80% of recipients of dry combined anthrax vaccine formed potent immunity with its high level lasted for 8 months. Study of allergenic properties of the combined anthrax vaccine using registration of neutrophils chemiluminescence in vivo showed low level of sensitization of vacinees.

Project BioShield: what it is, why it is needed, and its accomplishments so far.

Project BioShield is a comprehensive effort involving the US Department of Health and Human Services (HHS), its component agencies, and other partner federal agencies to speed the research, development, acquisition, and availability of medical countermeasures to improve the government's preparedness for and ability to counter chemical, biological, radiological, and nuclear threat agents. The legislation authorizes use of the Special Reserve Fund, which makes available $5.6 billion over 10 years for the advanced development and purchase of medical countermeasures. This appropriation is intended to provide an economic incentive to the pharmaceutical industry to develop medical countermeasures for which the government is the only significant market. Acquisitions under Project BioShield are restricted to products in development that are potentially licensable within 8 years from the time of contract award. In exercising the procurement authorities under Project BioShield, HHS has launched acquisition programs to address each of the 4 threat agents, including Bacillus anthracis (anthrax), smallpox virus, botulinum toxins, and radiological/nuclear agents, originally deemed by the Department of Homeland Security to be threats to the US population sufficient to affect national security. At the time of writing, 7 contracts have been awarded: (1) recombinant protective antigen anthrax vaccine, the next-generation anthrax vaccine (contract terminated in December 2006 for default); (2) anthrax vaccine adsorbed, the currently licensed anthrax vaccine; (3) anthrax therapeutics (monoclonal); (4) anthrax therapeutics (human immune globulin); (5) the pediatric formulation of potassium iodide; (6) Ca- and Zn-diethylenetriaminepentaacetate (DTPA), chelating agents to treat ingestion of certain radiological particles; and (7) botulinum antitoxins. Additional acquisition contracts are expected to be awarded in 2007.

Assessment of anthrax vaccination data in the Defense Medical Surveillance System, 1998-2004.

PURPOSE: Understanding the completeness and accuracy of U.S. military anthrax vaccination data is important to the design and interpretation of studies to assess the safety of anthrax vaccine. We estimated the agreement between electronically recorded anthrax vaccination data in the Defense Medical Surveillance System (DMSS) versus anthrax vaccination data abstracted from hardcopy medical charts in a representative sample of the U.S. military from 1998 to 2004. METHODS: Medical chart abstractions were conducted at 28 military treatment facilities for 4201 personnel. Abstracted anthrax vaccination data for 1817 personnel, representing 7400 anthrax vaccine doses, were compared with electronically captured data in the DMSS from 1998 to 2004. Sensitivity, positive predictive value (PPV), specificity and negative predictive value (NPV) were calculated using weighted analyses. RESULTS: Weighted person-level analysis revealed DMSS sensitivity = 93.8% (95%CI = 91.1, 95.8), specificity = 87.0% (79.0, 92.3), PPV = 85.6% (77.2, 91.3) and NPV = 94.5% (91.7, 96.4). Report of anthrax vaccination within a +/-7 days window in both medical chart and DMSS electronic data had a sensitivity of 88.3% (85.4, 90.7) and a PPV of 86.6% (84.9, 88.2) in the vaccine dose-level analysis. CONCLUSIONS: These results support that anthrax vaccination data captured by the DMSS are adequate for post-marketing surveillance investigations in the U.S. military and are of comparable quality to data captured by other vaccine safety databases.

Responding to a small-scale bioterrorist anthrax attack: cost-effectiveness analysis comparing preattack vaccination with postattack antibiotic treatment and vaccination.

BACKGROUND: In 2001, a small-scale bioterrorism-related anthrax attack was perpetrated via the US mail. The optimal future response may require strategies different from those required in a large-scale attack. METHODS: We conducted a cost-effectiveness analysis using Monte Carlo simulation during a 10-year time frame from a societal perspective to determine the optimal response strategy for a small-scale anthrax attack perpetrated against US Postal Service distribution centers in a large metropolitan area. Three strategies were compared: preattack vaccination of all US distribution center postal workers, postattack antibiotic therapy followed by vaccination of exposed personnel, and postattack antibiotic therapy without vaccination of exposed personnel. Outcome measures were costs, quality-adjusted life-years, and incremental cost-effectiveness. The probabilities for anthrax exposure and infection; vaccine and antibiotic benefits, risks, and costs; and associated clinical outcomes were derived from the medical literature and from bioterrorism experts. RESULTS: Postattack antibiotic therapy and vaccination of exposed postal workers is the most cost-effective response compared with other strategies. The incremental cost-effectiveness is $59 558 per quality-adjusted life-year compared with postattack antibiotic therapy alone. Preattack vaccination of all distribution center workers is less effective and more costly than the other 2 strategies. Assuming complete adherence to preattack vaccination, the incremental cost-effectiveness compared with postattack antibiotic therapy alone is almost $2.6 million per quality-adjusted life-year. CONCLUSION: Despite uncertainties about a future anthrax attack and exposure risk, postattack antibiotic therapy and vaccination of exposed personnel seems to be the optimal response to an attack perpetrated through the US Postal Service.