Chemical and Biological Threats to Public Safety
Frank A. Barile in Barile’s Clinical Toxicology, 2019
The anthrax vaccine is an effective control measure and was developed from an attenuated strain of B. anthracis. Clinical studies have calculated the efficacy level of the vaccine at about 92.5%. The vaccine derives from cell-free culture filtrates of this strain and in its final formulation, is adsorbed onto an aluminum salt. The licensed anthrax vaccine, anthrax vaccine adsorbed (AVA),* is recommended for individuals at risk for occupational exposure and persons involved with diagnostic, clinical, or investigational activities with B. anthracis spores. Vaccination is not available to the general public and is not recommended to prevent disease.
Vaccines against anthrax based on recombinant protective antigen: problems and solutions
Published in Expert Review of Vaccines, 2019
Olga A. Kondakova, Nikolai A. Nikitin, Ekaterina A. Evtushenko, Ekaterina M. Ryabchevskaya, Joseph G. Atabekov, Olga V. Karpova
Live attenuated strains of Salmonella spp. are a promising platform for antigen delivery and anthrax vaccine design. Recombinant strains of S. Typhi, expressing PA plasmids and using different approaches to enable stable expression of anthrax toxin protective antigen, were engineered [68–71]. Vaccinating mice and non-human primates with recombinant strains individually, or in a prime-boost scheme with licensed AVA vaccine or purified PA, demonstrated the efficacy of this approach in ensuring protection against B. аnthracis (Table 1). In a number of studies, the PA gene was integrated into a bacterial chromosome to increase the stability of the bacterial vector [72,73]. Recently, Sim et al. [73] engineered a genetically stable recombinant strain with a codon-optimized PA integrated into the chromosome of the licensed vaccine strain of S. Typhi Ty21a. Immunized mice were completely protected against intranasal challenge with avirulent (pXO1+/pXO2-) B. anthracis Sterne strain spores (5 LD50), and 70% of vaccinated rabbits were protected against aerosol virulent (pXO1+/pXO2+) Ames strain spore (200 LD50) challenge. The vaccine was foam-dried, and the dried product retained ~50% viability for 20 months at ambient temperature [73].
Vaccines, Military Culture, and Cynicism: Exploring COVID-19 Vaccination Attitudes among Veterans in Homeless Transitional Housing
Published in Military Behavioral Health, 2022
June L. Gin, Michelle D. Balut, Aram Dobalian
When asked about their willingness to accept the COVID-19 vaccine, six of the 20 Veterans noted that they had received mandatory vaccines in the military. Four of these six Veterans had either received the vaccine or wanted to receive it, while two were reluctant. Of the Veterans who mentioned mandatory military vaccinations and were willing to be vaccinated for COVID-19, two of them mentioned that they had also received the anthrax vaccine as part of the Operation Enduring Freedom/Operation Iraqi Freedom (OEF/OIF) cohort that served in the U.S. wars in Afghanistan and/or Iraq that began in 2001 and 2003, respectively. The anthrax vaccine, mandatory for personnel serving in the Middle East, became controversial, as it was found to cause severe adverse reactions in 85% of U.S. Air Force members who were vaccinated and led to a 16% attrition rate among those required to receive it (U.S. Government Accountability Office, September 20, 2002). “Massachusetts4,” who eagerly received the COVID-19 vaccine in January 2021, recounted the widespread cynicism and distrust that the anthrax vaccine generated from himself and other military members:
Efficacy assessment of a triple anthrax chimeric antigen as a vaccine candidate in guinea pigs: challenge test with Bacillus anthracis 17 JB strain spores
Published in Immunopharmacology and Immunotoxicology, 2021
Masoud Abdous, Sadegh Hasannia, Ali Hatef Salmanian, Seyed-Shahryar Arab
Anthrax is an acute infection in humans and animals caused by B. anthracis. There are commercial anthrax vaccines consisting of Bacillus anthracis spore and protective antigen (PA) to prevent veterinary and human infection, respectively. Veterinary anthrax vaccine has many limitations. First, sick, weak, and young (under three months of age) cattle should not be vaccinated; second, the cattle should be slaughtered at least 3 weeks after vaccination (6 weeks for pregnant animals) and third, there is a possibility of anaphylactic reactions after vaccination of some sensitive livestock breeds requiring veterinary care and adrenaline injection [18]. Furthermore, the FDA approved human anthrax vaccine has a 92.5% efficacy for protection in both cutaneous and inhalational anthrax cases and may not protect all individuals [22]. Therefore, improved methods should be used in order to reduce or eliminate common problems of veterinary and human anthrax vaccines. Many studies found that fusion of different domains of anthrax antigens could be considered a more efficient potential candidate subunit vaccine compared to single antigen vaccines, and also showed the functional role of antibodies in protection against microbial infections [23,24]. Some studies showed that not only the protective antigen (PA) could play an important role in protection against anthrax but also the lethal factor (LF) and the edema factor (EF) stimulate the production of toxin neutralizing antibodies. In addition, PA with LF/EF separately or in the fusion form has synergistic effects as a potential subunit vaccine. It has been reported that a combination of antibodies against PA and LF increases the efficiency of the anthrax toxins neutralization capacity, offers 100% protection against B. anthracis challenges in immunized mice models, and has synergistic protective efficacy [4,25]. Moreover, EF plays a role in eliciting protective immunity against anthrax and should be included in the new generation of multi-component subunit vaccines [26]. EF neutralizing antibodies may cross-react with LF and further protect host cells from anthrax toxins because of the structural similarities between the first domains of EF (EFD1) and the first domains of LF (LFD1) [26]. Furthermore, neutralization of EF and PA could produce synergistic beneficial effects [27]. Previous studies found that chimeric protein produced by fuzing the protective antigen (PA)-binding domain of lethal factor (LFn) to dominant-negative inhibitory PA (DPA) called LFn-DPA. LFn-DPA exhibits a strong potency in rescuing mice from challenge with LeTx. Anti-LF monoclonal antibodies also could cross-react with EF [28,29]. Other study showed that a chimeric vaccine comprising LFD1 and the C-terminal domain of PA (PAD4) would offer a broader spectrum of protection compared to PA alone [4]. Another study displayed that the use of PA-LFD1 chimeric protein enhanced the humoral and cellular immune response in mice, and concluded that this protein could be a better alternative to the PA-based recombinant anthrax vaccine [12].
Related Knowledge Centers
- Anthrax
- Bacillus Anthracis
- Bacteria
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- Fever
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- Vaccine
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