Clinical Recognition and Management of Patients Exposed to Biological Warfare Agents

Comparative overview of emerging RNA viruses: Epidemiology, pathogenesis, diagnosis and current treatment

From many decades, emerging infections have threatened humanity. The pandemics caused by different CoVs have already claimed and will continue to claim millions of lives. The SARS, Ebola, MERS epidemics and the most recent emergence of COVID-19 pandemic have threatened populations across borders. Since a highly pathogenic CoV has been evolved into the human population in the twenty-first century known as SARS, scientific advancements and innovative methods to tackle these viruses have increased in order to improve response preparedness towards the unpredictable threat posed by these rapidly emerging pathogens. Recently published review articles on SARS-CoV-2 have mainly focused on its pathogenesis, epidemiology and available treatments. However, in this review, we have done a systematic comparison of all three CoVs i.e., SARS, MERS and SARS-CoV-2 along with Ebola and Zika in terms of their epidemiology, virology, clinical features and current treatment strategies. This review focuses on important emerging RNA viruses starting from Zika, Ebola and the CoVs which include SARS, MERS and SARS-CoV-2. Each of these viruses has been elaborated on the basis of their epidemiology, virulence, transmission and treatment. However, special attention has been given to SARS-CoV-2 and the disease caused by it i.e., COVID-19 due to current havoc caused worldwide. At the end, insights into the current understanding of the lessons learned from previous epidemics to combat emerging CoVs have been described. The travel-related viral spread, the unprecedented nosocomial outbreaks and the high case-fatality rates associated with these highly transmissible and pathogenic viruses highlight the need for new prophylactic and therapeutic actions which include but are not limited to clinical indicators, contact tracing, and laboratory investigations as important factors that need to be taken into account in order to arrive at the final conclusion.

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Recently published review articles on SARS-CoV-2 have mainly focused on its pathogenesis, epidemiology and available treatments.

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The pandemics caused by different CoVs have already claimed and will continue to claim millions of lives.

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This review focuses on important emerging RNA viruses starting from Zika, Ebola and the CoVs which include SARS, MERS and SARS-CoV-2.

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Globally, numerous studies and researchers have recently started fighting this virus.

A DNA vaccine targeting VEE virus delivered by needle-free jet-injection protects macaques against aerosol challenge

We have previously shown that DNA vaccines expressing codon optimized alphavirus envelope glycoprotein genes protect both mice and nonhuman primates from viral challenge when delivered by particle-mediated epidermal delivery (PMED) or intramuscular (IM) electroporation (EP). Another technology with fewer logistical drawbacks is disposable syringe jet injection (DSJI) devices developed by PharmaJet, Inc. These needle-free jet injection systems are spring-powered and capable of delivering vaccines either IM or into the dermis (ID). Here, we evaluated the immunogenicity of our Venezuelan equine encephalitis virus (VEEV) DNA vaccine delivered by either the IM- or ID-DSJI devices in nonhuman primates. The protective efficacy was assessed following aerosol challenge. We found that a prime and single boost by either the IM or ID route resulted in humoral and cellular immune responses that provided significant protection against disease and viremia. Although the ID route utilized one-fifth the DNA dose used in the IM route of vaccination, and the measured humoral and cellular immune responses trended lower, the level of protection was high and performed as well as the IM route for several clinical endpoints.

Development of Nanosensors Based Intelligent Packaging Systems: Food Quality and Medicine

The issue of medication noncompliance has resulted in major risks to public safety and financial loss. The new omnipresent medicine enabled by the Internet of things offers fascinating new possibilities. Additionally, an in-home healthcare station (IHHS), it is necessary to meet the rapidly increasing need for routine nursing and on-site diagnosis and prognosis. This article proposes a universal and preventive strategy to drug management based on intelligent and interactive packaging (I2Pack) and IMedBox. The controlled delamination material (CDM) seals and regulates wireless technologies in novel medicine packaging. As such, wearable biomedical sensors may capture a variety of crucial parameters via wireless communication. On-site treatment and prediction of these critical factors are made possible by high-performance architecture. The user interface is also highlighted to make surgery easier for the elderly, disabled, and patients. Land testing incorporates and validates an approach for prototyping I2Pack and iMedBox. Additionally, sustainability, increased product safety, and quality standards are crucial throughout the life sciences. To achieve these standards, intelligent packaging is also used in the food and pharmaceutical industries. These technologies will continuously monitor the quality of a product and communicate with the user. Data carriers, indications, and sensors are the three most important groups. They are not widely used at the moment, although their potential is well understood. Intelligent packaging should be used in these sectors and the functionality of the systems and the values presented in this analysis.

Neurologic Manifestations of the World Health Organization's List of Pandemic and Epidemic Diseases

The World Health Organization (WHO) monitors the spread of diseases globally and maintains a list of diseases with epidemic or pandemic potential. Currently listed diseases include Chikungunya, cholera, Crimean-Congo hemorrhagic fever, Ebola virus disease, Hendra virus infection, influenza, Lassa fever, Marburg virus disease, Neisseria meningitis, MERS-CoV, monkeypox, Nipah virus infection, novel coronavirus (COVID-19), plague, Rift Valley fever, SARS, smallpox, tularemia, yellow fever, and Zika virus disease. The associated pathogens are increasingly important on the global stage. The majority of these diseases have neurological manifestations. Those with less frequent neurological manifestations may also have important consequences. This is highlighted now in particular through the ongoing COVID-19 pandemic and reinforces that pathogens with the potential to spread rapidly and widely, in spite of concerted global efforts, may affect the nervous system. We searched the scientific literature, dating from 1934 to August 2020, to compile data on the cause, epidemiology, clinical presentation, neuroimaging features, and treatment of each of the diseases of epidemic or pandemic potential as viewed through a neurologist's lens. We included articles with an abstract or full text in English in this topical and scoping review. Diseases with epidemic and pandemic potential can be spread directly from human to human, animal to human, via mosquitoes or other insects, or via environmental contamination. Manifestations include central neurologic conditions (meningitis, encephalitis, intraparenchymal hemorrhage, seizures), peripheral and cranial nerve syndromes (sensory neuropathy, sensorineural hearing loss, ophthalmoplegia), post-infectious syndromes (acute inflammatory polyneuropathy), and congenital syndromes (fetal microcephaly), among others. Some diseases have not been well-characterized from a neurological standpoint, but all have at least scattered case reports of neurological features. Some of the diseases have curative treatments available while in other cases, supportive care remains the only management option. Regardless of the pathogen, prompt, and aggressive measures to control the spread of these agents are the most important factors in lowering the overall morbidity and mortality they can cause.

Comparative pathology study of Venezuelan, eastern, and western equine encephalitis viruses in non-human primates

Venezuelan, eastern, and western equine encephalitis viruses (VEEV, EEEV, and WEEV) are mosquito-borne viruses in the Americas that cause central nervous system (CNS) disease in humans and equids. In this study, we directly characterized the pathogenesis of VEEV, EEEV, and WEEV in cynomolgus macaques following subcutaneous exposure because this route more closely mimics natural infection via mosquito transmission or by an accidental needle stick. Our results highlight how EEEV is significantly more pathogenic compared to VEEV similarly to what is observed in humans. Interestingly, EEEV appears to be just as neuropathogenic by subcutaneous exposure as it was in previously completed aerosol exposure studies. In contrast, subcutaneous exposure of cynomolgus macaques with WEEV caused limited disease and is contradictory to what has been reported for aerosol exposure. Several differences in viremia, hematology, or tissue tropism were noted when animals were exposed subcutaneously compared to prior aerosol exposure studies. This study provides a more complete picture of the pathogenesis of the encephalitic alphaviruses and highlights how further defining the neuropathology of these viruses could have important implications for the development of medical countermeasures for the neurovirulent alphaviruses.

Nanoplasmid Vectors Co-expressing Innate Immune Agonists Enhance DNA Vaccines for Venezuelan Equine Encephalitis Virus and Ebola Virus

DNA vaccines expressing codon-optimized Venezuelan equine encephalitis virus (VEEV) and Ebola virus (EBOV) glycoprotein genes provide protective immunity to mice and nonhuman primates when delivered by intramuscular (IM) electroporation (EP). To achieve equivalent protective efficacy in the absence of EP, we evaluated VEEV and EBOV DNA vaccines constructed using minimalized Nanoplasmid expression vectors that are smaller than conventional plasmids used for DNA vaccination. These vectors may also be designed to co-express type I interferon inducing innate immune agonist genes that have an adjuvant effect. Nanoplasmid vaccinated mice had increased antibody responses as compared to those receiving our conventional pWRG7077-based vaccines when delivered by IM injection, and these responses were further enhanced by the inclusion of the innate immune agonist genes. The Nanoplasmid VEEV DNA vaccines also significantly increased protection against aerosol VEEV challenge as compared to the pWRG7077 VEEV DNA vaccine. Although all mice receiving the pWRG7077 and Nanoplasmid EBOV DNA vaccines at the dose tested survived EBOV challenge, only mice receiving the Nanoplasmid EBOV DNA vaccine that co-expresses the innate immune agonist genes failed to lose weight after challenge. Our results suggest that Nanoplasmid vectors can improve the immunogenicity and protective efficacy of alphavirus and filovirus DNA vaccines.

Nanoscale Phenotypic Textures of Yersinia pestis Across Environmentally-Relevant Matrices

The persistence of bacterial pathogens within environmental matrices plays an important role in the epidemiology of diseases, as well as impacts biosurveillance strategies. However, the adaptation potentials, mechanisms for survival, and ecological interactions of pathogenic bacteria such as Yersinia pestis are largely uncharacterized owing to the difficulty of profiling their phenotypic signatures. In this report, we describe studies on Y. pestis organisms cultured within soil matrices, which are among the most important reservoirs for their propagation. Morphological (nanoscale) and phenotypic analysis are presented at the single cell level conducted using Atomic Force Microscopy (AFM), coupled with biochemical profiles of bulk populations using Fatty Acid Methyl Ester Profiling (FAME). These studies are facilitated by a novel, customizable, 3D printed diffusion chamber that allows for control of the external environment and easy harvesting of cells. The results show that incubation within soil matrices lead to reduction of cell size and an increase in surface hydrophobicity. FAME profiles indicate shifts in unsaturated fatty acid compositions, while other fatty acid components of the phospholipid membrane or surface lipids remained consistent across culturing conditions, suggesting that phenotypic shifts may be driven by non-lipid components of Y. pestis.

Characterization of Brain Inflammation, Apoptosis, Hypoxia, Blood-Brain Barrier Integrity and Metabolism in Venezuelan Equine Encephalitis Virus (VEEV TC-83) Exposed Mice by In Vivo Positron Emission Tomography Imaging

Traditional pathogenesis studies of alphaviruses involves monitoring survival, viremia, and pathogen dissemination via serial necropsies; however, molecular imaging shifts this paradigm and provides a dynamic assessment of pathogen infection. Positron emission tomography (PET) with PET tracers targeted to study neuroinflammation (N,N-diethyl-2-[4-phenyl]-5,7-dimethylpyrazolo[1,5-a]pyrimidine-3-acetamide, [¹⁸F]DPA-714), apoptosis (caspase-3 substrate, [¹⁸F]CP-18), hypoxia (fluormisonidazole, [¹⁸F]FMISO), blood–brain barrier (BBB) integrity ([¹⁸F]albumin), and metabolism (fluorodeoxyglucose, [¹⁸F]FDG) was performed on C3H/HeN mice infected intranasally with 7000 plaque-forming units (PFU) of Venezuelan equine encephalitis virus (VEEV) TC-83. The main findings are as follows: (1) whole-brain [¹⁸F]DPA-714 and [¹⁸F]CP-18 uptake increased three-fold demonstrating, neuroinflammation and apoptosis, respectively; (2) [¹⁸F]albumin uptake increased by 25% across the brain demonstrating an altered BBB; (3) [¹⁸F]FMISO uptake increased by 50% across the whole brain indicating hypoxic regions; (4) whole-brain [¹⁸F]FDG uptake was unaffected; (5) [¹⁸F]DPA-714 uptake in (a) cortex, thalamus, striatum, hypothalamus, and hippocampus increased through day seven and decreased by day 10 post exposure, (b) olfactory bulb increased at day three, peaked day seven, and decreased day 10, and (c) brain stem and cerebellum increased through day 10. In conclusion, intranasal exposure of C3H/HeN mice to VEEV TC-83 results in both time-dependent and regional increases in brain inflammation, apoptosis, and hypoxia, as well as modest decreases in BBB integrity; however, it has no effect on brain glucose metabolism.

EGR1 upregulation following Venezuelan equine encephalitis virus infection is regulated by ERK and PERK pathways contributing to cell death

Venezuelan equine encephalitis virus (VEEV) is a neurotropic virus that causes significant disease in both humans and equines. Here we characterized the impact of VEEV on signaling pathways regulating cell death in human primary astrocytes. VEEV productively infected primary astrocytes and caused an upregulation of early growth response 1 (EGR1) gene expression at 9 and 18 h post infection. EGR1 induction was dependent on extracellular signal-regulated kinase1/2 (ERK1/2) and protein kinase R (PKR)-like endoplasmic reticulum kinase (PERK), but not on p38 mitogen activated protein kinase (MAPK) or phosphoinositide 3-kinase (PI3K) signaling. Knockdown of EGR1 significantly reduced VEEV-induced apoptosis and impacted viral replication. Knockdown of ERK1/2 or PERK significantly reduced EGR1 gene expression, dramatically reduced viral replication, and increased cell survival as well as rescued cells from VEEV-induced apoptosis. These data indicate that EGR1 activation and subsequent cell death are regulated through ERK and PERK pathways in VEEV infected primary astrocytes.

A Methodology for Determining Which Diseases Warrant Care in a High-Level Containment Care Unit

Although the concept of high-level containment care (HLCC or 'biocontainment'), dates back to 1969, the 2014-2016 outbreak of Ebola virus disease (EVD) brought with it a renewed emphasis on the use of specialized HLCC units in the care of patients with EVD. Employment of these units in the United States and Western Europe resulted in a significant decrease in mortality compared to traditional management in field settings. Moreover, this employment appeared to significantly lessen the risk of nosocomial transmission of disease; no secondary cases occurred among healthcare workers in these units. While many now accept the wisdom of utilizing HLCC units and principles in the management of EVD (and, presumably, of other transmissible and highly hazardous viral hemorrhagic fevers, such as those caused by Marburg and Lassa viruses), no consensus exists regarding additional diseases that might warrant HLCC. We propose here a construct designed to make such determinations for existing and newly discovered diseases. The construct examines infectivity (as measured by the infectious dose needed to infect 50% of a given population (ID50)), communicability (as measured by the reproductive number (R0)), and hazard (as measured by morbidity and mortality). Diseases fulfilling all three criteria (i.e., those that are highly infectious, communicable, and highly hazardous) are considered candidates for HLCC management if they also meet a fourth criterion, namely that they lack effective and available licensed countermeasures.

The genetic adjuvant IL-12 enhances the protective efficacy of a DNA vaccine for Venezuelan equine encephalitis virus delivered by intramuscular injection in mice

We have previously shown that DNA vaccines expressing codon-optimized alphavirus envelope glycoprotein genes protect both mice and non-human primates from viral challenge when delivered by intramuscular electroporation (IM-EP). To determine if we could achieve equivalent immunogenicity and protective efficacy in the absence of electroporation, we co-delivered our Venezuelan equine encephalitis virus (VEEV) DNA vaccine with DNA plasmids expressing genetic adjuvants designed to augment immune responses. We tested the T_h1-inducing cytokine IL-12 as well as the granulocyte growth factor GM-CSF, both of which have demonstrated significant adjuvant effect when included in clinical DNA vaccine formulations. Additionally, as multiple reports have described the necessity of IFN-αβ in DNA vaccine immunogenicity, we tested vaccine plasmids encoding a potent stimulator of the IFN-αβ pathway. Our data suggest that IM vaccination of mice with plasmid DNA encoding genetic adjuvants enhances VEEV vaccine immunogenicity, resulting in improved T cell responses, as well as skewing of the anti-VEEV IgG antibody isotype. Additionally, IM vaccination of VEEV DNA vaccine and IL-12 provided complete protection against aerosol VEEV challenge. Overall, our data suggest that co-delivery of genetic adjuvants with alphavirus DNA vaccines using IM delivery can influence the type of immune response obtained and provide comparable protective immunity to that achieved by IM-EP delivery of the vaccine without adjuvants.

A Multiagent Alphavirus DNA Vaccine Delivered by Intramuscular Electroporation Elicits Robust and Durable Virus-Specific Immune Responses in Mice and Rabbits and Completely Protects Mice against Lethal Venezuelan, Western, and Eastern Equine Encephalitis Virus Aerosol Challenges

There remains a need for vaccines that can safely and effectively protect against the biological threat agents Venezuelan (VEEV), western (WEEV), and eastern (EEEV) equine encephalitis virus. Previously, we demonstrated that a VEEV DNA vaccine that was optimized for increased antigen expression and delivered by intramuscular (IM) electroporation (EP) elicited robust and durable virus-specific antibody responses in multiple animal species and provided complete protection against VEEV aerosol challenge in mice and nonhuman primates. Here, we performed a comparative evaluation of the immunogenicity and protective efficacy of individual optimized VEEV, WEEV, and EEEV DNA vaccines with that of a 1 : 1 : 1 mixture of these vaccines, which we have termed the 3-EEV DNA vaccine, when delivered by IM EP. The individual DNA vaccines and the 3-EEV DNA vaccine elicited robust and durable virus-specific antibody responses in mice and rabbits and completely protected mice from homologous VEEV, WEEV, and EEEV aerosol challenges. Taken together, the results from these studies demonstrate that the individual VEEV, WEEV, and EEEV DNA vaccines and the 3-EEV DNA vaccine delivered by IM EP provide an effective means of eliciting protection against lethal encephalitic alphavirus infections in a murine model and represent viable next-generation vaccine candidates that warrant further development.

Highly sensitive detection of a bio-threat pathogen by gold nanoparticle-based oligonucleotide-linked immunosorbent assay

Francisella (F.) tularensis causes the zoonotic disease tularemia and categorized as one of the highest-priority biological agents. The sensing approaches utilized by conventional detection methods, including enzyme-linked immunosorbent assay (ELISA), are not sensitive enough to identify an infectious dose of this high-risk pathogen due to its low infective dose. As an attempt to detect F. tularensis with high sensitivity, we utilized the highly sensitive immunoassay system named gold nanoparticle-based oligonucleotide-linked immunosorbent assay (GNP-OLISA) which uses antibody-gold nanoparticles conjugated with DNA strands as a signal generator and RNA oligonucleotides appended with a fluorophore as a quencher for signal amplification. We modified the GNP-OLISA for the detection F. tularensis to utilize one antibody for both the capture of the target and for signal generation instead of using two different antibodies, which are usually employed to construct the antibody sandwich in the ELISA. The GNP-OLISA showed 37-fold higher sensitivity compared with ELISA and generated very consistent detection results in the sera. In addition, the detection specificity was not affected by the presence of non-target bacteria, suggesting that GNP-OLISA can be used as a sensitive detection platform for monitoring high-risk pathogens thereby overcoming the limit of the conventional assay system.

Elimination of bioweapons agents from forensic samples during extraction of human DNA

Collection of DNA for genetic profiling is a powerful means for the identification of individuals responsible for crimes and terrorist acts. Biologic hazards, such as bacteria, endospores, toxins, and viruses, could contaminate sites of terrorist activities and thus could be present in samples collected for profiling. The fate of these hazards during DNA isolation has not been thoroughly examined. Our goals were to determine whether the DNA extraction process used by the Royal Canadian Mounted Police eliminates or neutralizes these agents and if not, to establish methods that render samples safe without compromising the human DNA. Our results show that bacteria, viruses, and toxins were reduced to undetectable levels during DNA extraction, but endospores remained viable. Filtration of samples after DNA isolation eliminated viable spores from the samples but left DNA intact. We also demonstrated that contamination of samples with some bacteria, endospores, and toxins for longer than 1 h compromised the ability to complete genetic profiling.

Pathology and pathophysiology of inhalational anthrax in a guinea pig model

Nonhuman primates (NHPs) and rabbits are the animal models most commonly used to evaluate the efficacy of medical countermeasures against anthrax in support of licensure under the FDA's "Animal Rule." However, a need for an alternative animal model may arise in certain cases. The development of such an alternative model requires a thorough understanding of the course and manifestation of experimental anthrax disease induced under controlled conditions in the proposed animal species. The guinea pig, which has been used extensively for anthrax pathogenesis studies and anthrax vaccine potency testing, is a good candidate for such an alternative model. This study was aimed at determining the median lethal dose (LD50) of the Bacillus anthracis Ames strain in guinea pigs and investigating the natural history, pathophysiology, and pathology of inhalational anthrax in this animal model following nose-only aerosol exposure. The inhaled LD50 of aerosolized Ames strain spores in guinea pigs was determined to be 5.0 × 10(4) spores. Aerosol challenge of guinea pigs resulted in inhalational anthrax with death occurring between 46 and 71 h postchallenge. The first clinical signs appeared as early as 36 h postchallenge. Cardiovascular function declined starting at 20 h postexposure. Hematogenous dissemination of bacteria was observed microscopically in multiple organs and tissues as early as 24 h postchallenge. Other histopathologic findings typical of disseminated anthrax included suppurative (heterophilic) inflammation, edema, fibrin, necrosis, and/or hemorrhage in the spleen, lungs, and regional lymph nodes and lymphocyte depletion and/or lymphocytolysis in the spleen and lymph nodes. This study demonstrated that the course of inhalational anthrax disease and the resulting pathology in guinea pigs are similar to those seen in rabbits and NHPs, as well as in humans.

Differential accumulation of genetic and phenotypic changes in Venezuelan equine encephalitis virus and Japanese encephalitis virus following passage in vitro and in vivo

The requirement to replicate in both vertebrate and invertebrate hosts is thought to limit the introduction of genetic changes into the genome of arboviruses. Serial passage under laboratory conditions will overcome this limitation allowing for genetic changes to be introduced and affecting the virulence of the virus for animals. In the studies detailed here, the consequence of removing the restriction of alternate replication was demonstrated to be different depending on the virus. Passing Venezuelan equine encephalitis virus in tissue culture cells, eggs or mice resulted in up to 11 nucleotide or amino acid changes but no significant change in the virulence of the virus for mice. Passing Japanese encephalitis virus (JEV) under the identical conditions resulted in as many as 22 nucleotide or amino acid changes that often resulted in improved survival probabilities. For JEV, most genetic changes along with the attenuated phenotype were selected within 5 passes.

A DNA vaccine for venezuelan equine encephalitis virus delivered by intramuscular electroporation elicits high levels of neutralizing antibodies in multiple animal models and provides protective immunity to mice and nonhuman primates

We evaluated the immunogenicity and protective efficacy of a DNA vaccine expressing codon-optimized envelope glycoprotein genes of Venezuelan equine encephalitis virus (VEEV) when delivered by intramuscular electroporation. Mice vaccinated with the DNA vaccine developed robust VEEV-neutralizing antibody responses that were comparable to those observed after administration of the live-attenuated VEEV vaccine TC-83 and were completely protected from a lethal aerosol VEEV challenge. The DNA vaccine also elicited strong neutralizing antibody responses in rabbits that persisted at high levels for at least 6 months and could be boosted by a single additional electroporation administration of the DNA performed approximately 6 months after the initial vaccinations. Cynomolgus macaques that received the vaccine by intramuscular electroporation developed substantial neutralizing antibody responses and after an aerosol challenge had no detectable serum viremia and had reduced febrile reactions, lymphopenia, and clinical signs of disease compared to those of negative-control macaques. Taken together, our results demonstrate that this DNA vaccine provides a potent means of protecting against VEEV infections and represents an attractive candidate for further development.

Immunogenicity and protective efficacy of a DNA vaccine against Venezuelan equine encephalitis virus aerosol challenge in nonhuman primates

A study to evaluate the immunogenicity and protective efficacy of a Venezuelan equine encephalitis virus (VEEV) DNA vaccine in an aerosol model of nonhuman primate infection was performed. Cynomolgus macaques vaccinated with a plasmid expressing the 26S structural genes of VEEV subtype IAB by particle-mediated epidermal delivery (PMED) developed virus-neutralizing antibodies. No serum viremia was detected in two out of three macaques vaccinated with the VEEV DNA after aerosol challenge with homologous virus, while one displayed a low viremia on a single day postchallenge. In contrast, all three macaques vaccinated with empty vector DNA developed a high viremia that persisted for at least 3 days after challenge. In addition, macaques vaccinated with the VEEV DNA had reduced febrile reactions, lymphopenia, and clinical signs of disease postchallenge as compared to negative control macaques. Therefore, although the sample size was small in this pilot study, these results indicate that a VEEV DNA vaccine administered by PMED can at least partially protect nonhuman primates against an aerosol VEEV challenge.

A rhesus macaque (Macaca mulatta) model of aerosol-exposure brucellosis (Brucella suis): pathology and diagnostic implications

The US Centers for Disease Control and Prevention lists Brucella as a potential bioterrorism threat requiring enhanced diagnostic capacity and surveillance (http://emergency.cdc.gov/bioterrorism/). Successful treatment and management of patients after exposure to biological threat agents depends on accurate and timely diagnosis, but many biothreat agents present with similar, vague clinical signs – commonly referred to as ‘flu-like illness’. Diagnosis of brucellosis is notoriously challenging, especially early in infection, and definitive diagnosis may require invasive methods, e.g. bone marrow biopsy. We studied the pathogenesis of Brucella suis aerosol infection in rhesus macaques in an effort to guide the diagnostic algorithm in case of possible intentional exposure of humans. Rhesus proved to be an excellent model for human brucellosis; the data showed that PCR DNA amplification testing of non-invasive diagnostic samples has the potential to definitively detect a point-source outbreak immediately and for several days after exposure.

Directed molecular evolution improves the immunogenicity and protective efficacy of a Venezuelan equine encephalitis virus DNA vaccine

We employed directed molecular evolution to improve the cross-reactivity and immunogenicity of the Venezuelan equine encephalitis virus (VEEV) envelope glycoproteins. The DNA encoding the E1 and E2 proteins from VEEV subtypes IA/B and IE, Mucambo virus (MUCV), and eastern and western equine encephalitis viruses (EEEV and WEEV) were recombined in vitro to create libraries of chimeric genes expressing variant envelope proteins. ELISAs specific for all five parent viruses were used in high-throughput screening to identify those recombinant DNAs that demonstrated cross-reactivity to VEEV, MUCV, EEEV, and WEEV after administration as plasmid vaccines in mice. Selected variants were then used to vaccinate larger cohorts of mice and their sera were assayed by both ELISA and by plaque reduction neutralization test (PRNT). Representative variants from a library in which the E1 gene from VEEV IA/B was held constant and only the E2 genes of the five parent viruses were recombined elicited significantly increased neutralizing antibody titers to VEEV IA/B compared to the parent DNA vaccine and provided improved protection against aerosol VEEV IA/B challenge. Our results indicate that it is possible to improve the immunogenicity and protective efficacy of alphavirus DNA vaccines using directed molecular evolution.

Prophylaxis after exposure to Coxiella burnetii

Postexposure prophylaxis may avert Q fever illness and death when the probability of exposure is above the population-specific threshold point.

Coxiella burnetii is a category B bioterrorism agent. We numerically evaluated the risks and benefits from postexposure prophylaxis (PEP) after an intentional release of C. burnetii to the general population, pregnant women, and other high-risk populations. For each group, we constructed a decision tree to estimate illness and deaths averted by use of PEP/100,000 population. We calculated the threshold points at which the number of PEP-related adverse events was equal to the cases averted. PEP was defined as doxycycline (100 mg 2×/day for 5 days), except for pregnant women, where we assumed a PEP of trimethoprim-sulfamethoxazole (160 mg/800 mg 2×/day) for the duration of the pregnancy. PEP would begin 8–12 days postexposure. On the basis of upper-bound probability estimates of PEP-related adverse events for doxycycline, we concluded that the risk for Q fever illness outweighs the risk for antimicrobial drug–related adverse events when the probability of C. burnetii exposure is >7% (pregnant women using trimethoprim-sulfamethoxazole = 16%).

Combinatorial ribavirin and interferon alfacon-1 therapy of acute arenaviral disease in hamsters

Several arenaviruses endemic to South America (Junin, Machupo, and Guanarito) and Africa (Lassa) are known to cause frequently fatal haemorrhagic fever. With the exception of ribavirin, which has demonstrated efficacy in cases of Lassa fever, there is no other effective therapeutic for the treatment of arenaviral haemorrhagic fever. We have recently reported that consensus interferon-a (IFN alfacon-1) can protect hamsters from lethal Pichinde virus (PCV) infection, which serves as a model for acute arenaviral disease in humans. Here we demonstrate highly effective therapy through the combined use of ribavirin with IFN alfacon-1 for the treatment of PCV infection in hamsters. Ribavirin was given orally, twice per day for 7 days, and IFN alfacon-1 was administered intraperitoneally once per day for 10 days. Treatments were initiated 1-5 days post-virus challenge using various dose combinations, many of which were less than optimal when the drugs were given independently. Combining suboptimal doses of ribavirin (5-10 mg/kg/day) with IFN alfacon-1 (5-10 microg/kg/day), we were able to demonstrate increased protection from mortality, reduced viral burden and liver disease, and greatly extended survival times as compared to treatments where drugs were administered alone. Our data indicate that combination therapy results in synergistic activity that may slow down the progression of the disease and decrease fatality rates associated with severe arenaviral infections in humans. Further, combination therapy reduces the effective dosage of ribavirin, which would serve to limit its toxicity.

Water and bioterrorism: preparing for the potential threat to U.S. water supplies and public health

Water supplies and water distribution systems represent potential targets for terrorist activity in the United States because of the critical need for water in every sector of our industrialized society. Even short-term disruption of water service can significantly impact a community, and intentional contamination of a municipal water system as part of a terrorist attack could lead to serious medical, public health, and economic consequences. Most practicing physicians and public health professionals in the United States have received limited training in the recognition and evaluation of waterborne disease from either natural or intentional contamination of water. Therefore, they are poorly prepared to detect water-related disease resulting from intentional contamination and may not be adequately trained to respond appropriately to a terrorist assault on water. The purpose of this review is to address this critical information gap and present relevant epidemiologic and clinical information for public health and medical practitioners who may be faced with addressing the recognition, management, and prevention of water terrorism in their communities.

Human leukocyte antigen-DQ8 transgenic mice: a model to examine the toxicity of aerosolized staphylococcal enterotoxin B

Staphylococcal enterotoxins (SEs) belong to a large group of bacterial exotoxins that cause severe immunopathologies, especially when delivered as an aerosol. SEs elicit the release of lethal amounts of cytokines by binding to major histocompatibility complex (MHC) class II and cross-linking susceptible T-cell receptors. Efforts to develop effective therapeutic strategies to protect against SEs delivered as an aerosol have been hampered by the lack of small animal models that consistently emulate human responses to these toxins. Here, we report that human leukocyte antigen-DQ8 (HLA-DQ8) transgenic (Tg) mice, but not littermate controls, succumbed to lethal shock induced by SEB aerosols without potentiation. Substantial amounts of perivascular edema and inflammatory infiltrates were noted in the lungs of Tg mice, similar to the pathology observed in nonhuman primates exposed by aerosol to SEB. Furthermore, the observed pathologies and lethal shock correlated with an upsurge in proinflammatory cytokine mRNA gene expression in the lungs and spleens, as well as with marked increases in the levels of proinflammatory circulating cytokines in the Tg mice. Unlike the case for littermate controls, telemetric evaluation showed significant hypothermia in Tg mice exposed to lethal doses of SEB. Taken together, these results show that this murine model will allow for the examination of therapeutics and vaccines developed specifically against SEB aerosol exposure and possibly other bacterial superantigens in the context of human MHC class II receptors.

Bioterrorism and the nervous system

Recent events of war, terrorist attacks, and mail-borne anthrax exposure have produced increasing awareness of potential bioterrorism attacks in the United States and other parts of the world. Physicians and healthcare personnel play a key role in identifying potential bioterrorist attacks. Early recognition and preparedness for bioterrorism-associated illnesses is especially important for neurologists because most bioterrorism agents can directly or indirectly affect the nervous system. This article reviews the neurologic manifestations, diagnosis, and treatments of syndromes caused by potential bioterrorism agents, as well as the potential side effects of vaccines against some of these agents.

Smallpox and live-virus vaccination in transplant recipients

Recent bioterrorism raises the specter of reemergence of smallpox as a clinical entity. The mortality of variola major infection ('typical smallpox') was approximately 30% in past outbreaks. Programs for smallpox immunization for healthcare workers have been proposed. Atypical forms of smallpox presenting with flat or hemorrhagic skin lesions are most common in individuals with immune deficits with historic mortality approaching 100%. Smallpox vaccination, even after exposure, is highly effective. Smallpox vaccine contains a highly immunogenic live virus, vaccinia. Few data exist for the impact of variola or safety of vaccinia in immunocompromised hosts. Both disseminated infection by vaccinia and person-to-person spread after vaccination are uncommon. When it occurs, secondary vaccinia has usually affected individuals with pre-existing skin conditions (atopic dermatitis or eczema) or with other underlying immune deficits. Historically, disseminated vaccinia infection was uncommon but often fatal even in the absence of the most severe form of disease, "progressive vaccinia". Some responded to vaccinia immune globulin. Smallpox exposure would be likely to cause significant mortality among immunocompromised hosts. In the absence of documented smallpox exposures, immunocompromised hosts should not be vaccinated against smallpox. Planning for bioterrorist events must include consideration of uniquely susceptible hosts.

Generation of protective immunity by inactivated recombinant staphylococcal enterotoxin B vaccine in nonhuman primates and identification of correlates of immunity

At this time there are no vaccines or therapeutics to protect against staphylococcal enterotoxin B (SEB) exposure. Here, we report vaccine efficacy of an attenuated SEB in a nonhuman primate model following lethal aerosol challenge and identify several biomarkers of protective immunity. Initial in vitro results indicated that the mutation of key amino acid residues in the major histocompatibility complex (MHC) class II binding sites of SEB produced a nontoxic form of SEB, which had little to no detectable binding to MHC class II molecules, and lacked T-cell stimulatory activities. When examined in a mouse model, we found that the attenuated SEB retained antigenic structures and elicited protective immune responses against wild-type SEB challenge. Subsequently, a vaccine regimen against SEB in a nonhuman primate model was partially optimized, and investigations of immune biomarkers as indicators of protection were performed. SEB-naïve rhesus monkeys were vaccinated two or three times with 5 or 20 microg of the attenuated SEB and challenged by aerosol with wild-type SEB toxin. Unlike exposure to the native toxin, the vaccine did not trigger the release of inflammatory cytokines (TNF alpha, IL6, or IFN gamma). All rhesus monkeys that developed anti-SEB serum titers > or = 10(4) and elicited high levels of neutralizing antibody survived the aerosol challenge. These findings suggest that the attenuated SEB is fully protective against aerosolized toxin when administered to unprimed subjects. Moreover, experiments presented in this study identified various biomarkers that showed substantial promise as correlates of immunity and surrogate endpoints for assessing in vivo biological responses in primates, and possibly in humans, to vaccines against SEs.

Correlation of body temperature with protection against staphylococcal enterotoxin B exposure and use in determining vaccine dose-schedule

The immunoprotective potential of a recombinant vaccine against the incapacitating effect of aerosolized staphylococcal enterotoxin B (SEB) in nonhuman primates is reported. SEB belongs to a family of structurally related superantigens responsible for serious, life threatening pathologies. Injecting the recombinant SEB vaccine did not induce temperature elevation in rhesus monkeys, a classical symptom of toxic-shock syndrome. No temperature elevation was noted following injection with control tetanus toxoid. In addition to 100% survival, we observed a clear correlation between vaccine dose and mitigation of temperature elevation after a lethal SEB aerosol challenge. We conclude that the recombinant SEB vaccine is non-pyrogenic and that monitoring changes in body temperature is an important biomarker of toxic shock in a primate animal model.

Defending against viruses in biowarfare. How to respond to smallpox, encephalitides, hemorrhagic fevers

The threat of bioterrorism with use of viruses is increasing. Smallpox, encephalitis, and hemorrhagic fevers are the most likely diseases to result from viral deployment. It is critical that all healthcare professionals become familiar with the clinical presentation, diagnosis, management, and prevention of these diseases. Awareness and preparedness are instrumental in reducing viral transmission and improving survival of the victims.