Showing papers on "Anthrax vaccines published in 2015"

Bacillus anthracis and Other Bacillus Species

Abstract: The genus Bacillus is a diverse group of spore-forming bacteria. Bacillus species have implications in both medical and biodefence aspects of microbiology. This chapter attempts to summarize key molecular aspects of these bacteria (with an emphasis on B. anthracis ). Topics discussed include bacteriology (sporulation and germination), pathogenesis and disease progression, species differentiation and detection, virulence factors (toxin and capsule), vaccines (current and next-generation anthrax vaccines), and animal models of anthrax. As evidenced by the breadth of information covered within this chapter, there has been a great deal of research performed on Bacillus species for more than a century.

Efficacy and immunogenicity of single-dose AdVAV intranasal anthrax vaccine compared to anthrax vaccine absorbed in an aerosolized spore rabbit challenge model.

Abstract: AdVAV is a replication-deficient adenovirus type 5-vectored vaccine expressing the 83-kDa protective antigen (PA83) from Bacillus anthracis that is being developed for the prevention of disease caused by inhalation of aerosolized B. anthracis spores. A noninferiority study comparing the efficacy of AdVAV to the currently licensed Anthrax Vaccine Absorbed (AVA; BioThrax) was performed in New Zealand White rabbits using postchallenge survival as the study endpoint (20% noninferiority margin for survival). Three groups of 32 rabbits were vaccinated with a single intranasal dose of AdVAV (7.5 × 10(7), 1.5 × 10(9), or 3.5 × 10(10) viral particles). Three additional groups of 32 animals received two doses of either intranasal AdVAV (3.5 × 10(10) viral particles) or intramuscular AVA (diluted 1:16 or 1:64) 28 days apart. The placebo group of 16 rabbits received a single intranasal dose of AdVAV formulation buffer. All animals were challenged via the inhalation route with a targeted dose of 200 times the 50% lethal dose (LD50) of aerosolized B. anthracis Ames spores 70 days after the initial vaccination and were followed for 3 weeks. PA83 immunogenicity was evaluated by validated toxin neutralizing antibody and serum anti-PA83 IgG enzyme-linked immunosorbent assays (ELISAs). All animals in the placebo cohort died from the challenge. Three of the four AdVAV dose cohorts tested, including two single-dose cohorts, achieved statistical noninferiority relative to the AVA comparator group, with survival rates between 97% and 100%. Vaccination with AdVAV also produced antibody titers with earlier onset and greater persistence than vaccination with AVA.

Enhanced Immune Response to DNA Vaccine Encoding Bacillus anthracis PA-D4 Protects Mice against Anthrax Spore Challenge.

Abstract: Anthrax has long been considered the most probable bioweapon-induced disease. The protective antigen (PA) of Bacillus anthracis plays a crucial role in the pathogenesis of anthrax. In the current study, we evaluated the efficiency of a genetic vaccination with the fourth domain (D4) of PA, which is responsible for initial binding of the anthrax toxin to the cellular receptor. The eukaryotic expression vector was designed with the immunoglobulin M (IgM) signal sequence encoding for PA-D4, which contains codon-optimized genes. The expression and secretion of recombinant protein was confirmed in vitro in 293T cells transfected with plasmid and detected by western blotting, confocal microscopy, and enzyme-linked immunosorbent assay (ELISA). The results revealed that PA-D4 protein can be efficiently expressed and secreted at high levels into the culture medium. When plasmid DNA was given intramuscularly to mice, a significant PA-D4-specific antibody response was induced. Importantly, high titers of antibodies were maintained for nearly 1 year. Furthermore, incorporation of the SV40 enhancer in the plasmid DNA resulted in approximately a 15-fold increase in serum antibody levels in comparison with the plasmid without enhancer. The antibodies produced were predominantly the immunoglobulin G2 (IgG2) type, indicating the predominance of the Th1 response. In addition, splenocytes collected from immunized mice produced PA-D4-specific interferon gamma (IFN-γ). The biodistribution study showed that plasmid DNA was detected in most organs and it rapidly cleared from the injection site. Finally, DNA vaccination with electroporation induced a significant increase in immunogenicity and successfully protected the mice against anthrax spore challenge. Our approach to enhancing the immune response contributes to the development of DNA vaccines against anthrax and other biothreats.

Generation and Characterization of Human Monoclonal Antibodies Targeting Anthrax Protective Antigen following Vaccination with a Recombinant Protective Antigen Vaccine.

Abstract: The anthrax protective antigen (PA) is the central component of the three-part anthrax toxin, and it is the primary immunogenic component in the approved AVA anthrax vaccine and the "next-generation" recombinant PA (rPA) anthrax vaccines. Animal models have indicated that PA-specific antibodies (AB) are sufficient to protect against infection with Bacillus anthracis. In this study, we investigated the PA domain specificity, affinity, mechanisms of neutralization, and synergistic effects of PA-specific antibodies from a single donor following vaccination with the rPA vaccine. Antibody-secreting cells were isolated 7 days after the donor received a boost vaccination, and 34 fully human monoclonal antibodies (hMAb) were identified. Clones 8H6, 4A3, and 22F1 were able to neutralize lethal toxin (LeTx) both in vitro and in vivo. Clone 8H6 neutralized LeTx by preventing furin cleavage of PA in a dose-dependent manner. Clone 4A3 enhanced degradation of nicked PA, thereby interfering with PA oligomerization. The mechanism of 22F1 is still unclear. A fourth clone, 2A6, that was protective only in vitro was found to be neutralizing in vivo in combination with a toxin-enhancing antibody, 8A7, which binds to domain 3 of PA and PA oligomers. These results provide novel insights into the antibody response elicited by the rPA vaccine and may be useful for PA-based vaccine and immunotherapeutic cocktail design.

Combinations of various CpG motifs cloned into plasmid backbone modulate and enhance protective immunity of viral replicon DNA anthrax vaccines

Abstract: DNA vaccines are generally weak stimulators of the immune system. Fortunately, their efficacy can be improved using a viral replicon vector or by the addition of immunostimulatory CpG motifs, although the design of these engineered DNA vectors requires optimization. Our results clearly suggest that multiple copies of three types of CpG motifs or combinations of various types of CpG motifs cloned into a viral replicon vector backbone with strong immunostimulatory activities on human PBMC are efficient adjuvants for these DNA vaccines to modulate and enhance protective immunity against anthrax, although modifications with these different CpG forms in vivo elicited inconsistent immune response profiles. Modification with more copies of CpG motifs elicited more potent adjuvant effects leading to the generation of enhanced immunity, which indicated a CpG motif dose-dependent enhancement of antigen-specific immune responses. Notably, the enhanced and/or synchronous adjuvant effects were observed in modification with combinations of two different types of CpG motifs, which provides not only a contribution to the knowledge base on the adjuvant activities of CpG motifs combinations but also implications for the rational design of optimal DNA vaccines with combinations of CpG motifs as "built-in" adjuvants. We describe an efficient strategy to design and optimize DNA vaccines by the addition of combined immunostimulatory CpG motifs in a viral replicon DNA plasmid to produce strong immune responses, which indicates that the CpG-modified viral replicon DNA plasmid may be desirable for use as vector of DNA vaccines.

A Review on Anthrax and its Public Health and Economic Importance

Abstract: 2 Abstract: Anthrax is an infectious disease caused by the bacteria Bacillus anthracis. The disease can affect both humans and animals although it is more common among livestock and wild animals with high economic significance. The disease occurs in herbivorous animals either through inhalation or by direct consumption of the spores during grazing in the wild. Carnivorous animals are infected by consuming the affected herbivorous animals, whereas, infection in humans usually occurs through contact with the spores either through ingestion, inhalation or direct contact. The disease does not spread from infected persons directly and spores are the source of infection; since the spores of Bacillus anthracisis is extremely resistant to natural condition and can survive for several decades in the environment. The spore enters in to the body and causes a serious outbreaks in tropical and sub tropical countries with high rainfall. It is evident that control of the infected animals, prevention of contact with the infected animals and contaminated animal products are quite important to disease control. It is recommended that if an animal anthrax case is confirmed, the affected property is quarantined, potentially exposed stock vaccinated; dead animals buried and contaminated sites disinfected. The quarantine is not released until occurrences of anthrax cases have ceased and at least six weeks have elapsed since the last round of vaccinations on the property and people who are exposed might be given anthrax vaccine to prevent disease. Bacillus anthraces are susceptible to different antibiotics like penicillin, chloramphenicol, streptomycin, tetracycline and erythromycin

Source tracking of an anthrax outbreak in northeastern China using complete genome analysis and MLVA genotyping

Abstract: Anthrax is caused by Bacillus anthracis, an etiological agent behind zoonotic diseases worldwide. B. anthracis is also one of the most dangerous bioterrorism agents. An anthrax outbreak took place in Liaoning Province in northeastern China in August 2012. It resulted in seven human infections and dozens of dead cows. One B. anthracis strain, named Han, was isolated from a dead cow. This strain showed minor pathogenicity in mice and was suspected to be derived from the locally administered vaccine strain, Vac. In order to determine if the Han isolate was derived from the vaccine strain Vac and to track the source of the anthrax outbreak and, so, exclude the possibility of terrorism attack, a complete genome sequencing of these two B. anthracis strains was conducted. With the genome sequencing data, canonical single nucleotide polymorphism (SNP) analysis and whole-genome SNP screening were performed. The results indicate that the Han strain was markedly different from the Vac strain. Further analysis by multiple-locus variable-number tandem repeat analysis (MLVA) showed that Han clustered with previously reported Chinese strains. The result of MLVA15 confirmed that the Han strain is a naturally occurring isolate instead of an engineered agent deliberately distributed by terrorists or other parties. In conclusion, our method used in this study not only facilitates epidemiological studies but also made it easier to distinguish naturally occurring outbreaks from intentionally released pathogens.

Immunization with a Recombinant, Pseudomonas fluorescens-Expressed, Mutant Form of Bacillus anthracis-Derived Protective Antigen Protects Rabbits from Anthrax Infection

Abstract: Protective antigen (PA), one of the components of the anthrax toxin, is the major component of human anthrax vaccine (Biothrax). Human anthrax vaccines approved in the United States and Europe consist of an alum-adsorbed or precipitated (respectively) supernatant material derived from cultures of toxigenic, non-encapsulated strains of Bacillus anthracis. Approved vaccination schedules in humans with either of these vaccines requires several booster shots and occasionally causes adverse injection site reactions. Mutant derivatives of the protective antigen that will not form the anthrax toxins have been described. We have cloned and expressed both mutant (PA SNKE167-ΔFF-315-E308D) and native PA molecules recombinantly and purified them. In this study, both the mutant and native PA molecules, formulated with alum (Alhydrogel), elicited high titers of anthrax toxin neutralizing anti-PA antibodies in New Zealand White rabbits. Both mutant and native PA vaccine preparations protected rabbits from lethal, aerosolized, B. anthracis spore challenge subsequent to two immunizations at doses of less than 1 μg.

Whole genome protein microarrays for serum profiling of immunodominant antigens of Bacillus anthracis

Abstract: A commercial Bacillus anthracis (Anthrax) whole genome protein microarray has been used to identify immunogenic Anthrax proteins (IAP) using sera from groups of donors with (a) confirmed B. anthracis naturally acquired cutaneous infection, (b) confirmed B. anthracis intravenous drug use-acquired infection, (c) occupational exposure in a wool-sorters factory, (d) humans and rabbits vaccinated with the UK Anthrax protein vaccine and compared to naive unexposed controls. Anti-IAP responses were observed for both IgG and IgA in the challenged groups; however the anti-IAP IgG response was more evident in the vaccinated group and the anti-IAP IgA response more evident in the B. anthracis-infected groups. Infected individuals appeared somewhat suppressed for their general IgG response, compared with other challenged groups. Immunogenic protein antigens were identified in all groups, some of which were shared between groups whilst others were specific for individual groups. The toxin proteins were immunodominant in all vaccinated, infected or other challenged groups. However, a number of other chromosomally-located and plasmid encoded open reading frame proteins were also recognized by infected or exposed groups in comparison to controls. Some of these antigens e.g., BA4182 are not recognized by vaccinated individuals, suggesting that there are proteins more specifically expressed by live Anthrax spores in vivo that are not currently found in the UK licensed Anthrax Vaccine (AVP). These may perhaps be preferentially expressed during infection and represent expression of alternative pathways in the B. anthracis "infectome." These may make highly attractive candidates for diagnostic and vaccine biomarker development as they may be more specifically associated with the infectious phase of the pathogen. A number of B. anthracis small hypothetical protein targets have been synthesized, tested in mouse immunogenicity studies and validated in parallel using human sera from the same study.

Natural cutaneous anthrax infection, but not vaccination, induces a CD4+ T cell response involving diverse cytokines

Abstract: Background Whilst there have been a number of insights into the subsets of CD4+ T cells induced by pathogenic Bacillus anthracis infections in animal models, how these findings relate to responses generated in naturally infected and vaccinated humans has yet to be fully established. We describe the cytokine profile produced in response to T cell stimulation with a previously defined immunodominant antigen of anthrax, lethal factor (LF), domain IV, in cohorts of individuals with a history of cutaneous anthrax, compared with vaccinees receiving the U.K. licenced Anthrax Vaccine Precipitated (AVP) vaccine.

Investigation of Anthrax Cases in North-East China, 2010-2014.

Abstract: We determined the genotypes of seven Bacillus anthracis strains that were recovered from nine anthrax outbreaks in North-East China from 2010 to 2014, and two approved vaccine strains that are currently in use in China. The causes of these cases were partly due to local farmers being unaware of the presence of anthrax, and butchers with open wounds having direct contact with anthrax-contaminated meat products. The genotype of five of the seven recovered strains was A.Br.001/002 sub-lineage, which was concordant with previously published research. The remaining two cases belongs to the A.Br.Ames sub-lineage. Both of these strains displayed an identical SNR pattern, which was the first time that this genotype was identified in North-East China. Strengthening education in remote villages of rural China is an important activity aimed at fostering attempts to prevent and control anthrax. The genotype of the vaccine strain Anthrax Spore Vaccine No.II was A.Br.008/009 and A.Br.001/002 for the vaccine strain Anthrax Spore Vaccine Non-capsulated. Further studies of their characteristics are clearly warranted.

Bacillus anthracis capsular conjugates elicit chimpanzee polyclonal antibodies that protect mice from pulmonary anthrax

Abstract: The immunogenicity of Bacillus anthracis capsule (poly-γ-d-glutamic acid [PGA]) conjugated to recombinant B. anthracis protective antigen (rPA) or to tetanus toxoid (TT) was evaluated in two anthrax-naive juvenile chimpanzees. In a previous study of these conjugates, highly protective monoclonal antibodies (MAbs) against PGA were generated. This study examines the polyclonal antibody response of the same animals. Preimmune antibodies to PGA with titers of >103 were detected in the chimpanzees. The maximal titer of anti-PGA was induced within 1 to 2 weeks following the 1st immunization, with no booster effects following the 2nd and 3rd immunizations. Thus, the anti-PGA response in the chimpanzees resembled a secondary immune response. Screening of sera from nine unimmunized chimpanzees and six humans revealed antibodies to PGA in all samples, with an average titer of 103. An anti-PA response was also observed following immunization with PGA-rPA conjugate, similar to that seen following immunization with rPA alone. However, in contrast to anti-PGA, preimmune anti-PA antibody titers and those following the 1st immunization were ≤300, with the antibodies peaking above 104 following the 2nd immunization. The polyclonal anti-PGA shared the MAb 11D epitope and, similar to the MAbs, exerted opsonophagocytic killing of B. anthracis. Most important, the PGA-TT–induced antibodies protected mice from a lethal challenge with virulent B. anthracis spores. Our data support the use of PGA conjugates, especially PGA-rPA targeting both toxin and capsule, as expanded-spectrum anthrax vaccines.

Immunization of Mice with Anthrax Protective Antigen Limits Cardiotoxicity but Not Hepatotoxicity Following Lethal Toxin Challenge.

Abstract: Protective immunity against anthrax is inferred from measurement of vaccine antigen-specific neutralizing antibody titers in serum samples. In animal models, in vivo challenges with toxin and/or spores can also be performed. However, neither of these approaches considers toxin-induced damage to specific organ systems. It is therefore important to determine to what extent anthrax vaccines and existing or candidate adjuvants can provide organ-specific protection against intoxication. We therefore compared the ability of Alum, CpG DNA and the CD1d ligand α-galactosylceramide (αGC) to enhance protective antigen-specific antibody titers, to protect mice against challenge with lethal toxin, and to block cardiotoxicity and hepatotoxicity. By measurement of serum cardiac Troponin I (cTnI), and hepatic alanine aminotransferase (ALT), and aspartate aminotransferase (AST), it was apparent that neither vaccine modality prevented hepatic intoxication, despite high Ab titers and ultimate survival of the subject. In contrast, cardiotoxicity was greatly diminished by prior immunization. This shows that a vaccine that confers survival following toxin exposure may still have an associated morbidity. We propose that organ-specific intoxication should be monitored routinely during research into new vaccine modalities.

Anthrax vaccine associated deaths in miniature horses.

Abstract: During a widespread anthrax outbreak in Canada, miniature horses were vaccinated using a live spore anthrax vaccine. Several of these horses died from an apparent immune-mediated vasculitis temporally associated with this vaccination. During the course of the outbreak, other miniature horses from different regions with a similar vaccination history, clinical signs, and necropsy findings were found.

US disaster planners' attitudes regarding preevent vaccine for first responders and point-of-dispensing workers.

Abstract: Disaster planners' attitudes toward preevent anthrax and smallpox vaccine for first responders and point-of-dispensing (POD) workers have not been examined. An online questionnaire was sent to US Cities Readiness Initiative (CRI) and non-CRI public health disaster planners in 2013. Multivariate logistic regressions were used to assess determinants of belief that first responders and POD workers should be offered the anthrax and/or smallpox vaccine before an event. A total of 301 disaster planners participated. Only half (50.6%, n=126) were aware of the ACIP recommendation that first responders could be offered preevent anthrax vaccine. Many (66.0%, n=164) believed that preevent anthrax vaccine should be offered to first responders. The oldest respondents were least likely to believe anthrax vaccine should be given (OR: 0.27, 0.12, 0.63, p<.001). Fewer disaster planners believed that preevent anthrax vaccine should be offered to POD workers compared to first responders (55.0% vs 66.0%, X2=151, p<.001). Alm...

Design and Testing of Novel Anthrax Vaccines Utilizing a Tobacco Mosaic Virus Expression System

Abstract: This Restricted to Claremont Colleges Dissertation is brought to you for free and open access by the KGI Student Scholarship at Scholarship @ Claremont. It has been accepted for inclusion in KGI Theses and Dissertations by an authorized administrator of Scholarship @ Claremont. For more information, please contact scholarship@cuc.claremont.edu. Recommended Citation McComb, Ryan C., "Design and Testing of Novel Anthrax Vaccines Utilizing a Tobacco Mosaic Virus Expression System" (2015). KGI Theses and Dissertations. Paper 3. http://scholarship.claremont.edu/kgi__theses/3