Passive immunotherapy of Bacillus anthracis pulmonary infection in mice with antisera produced by DNA immunization

High-dimensional analysis of 16 SARS-CoV-2 vaccine combinations reveals lymphocyte signatures correlating with immunogenicity

The range of vaccines developed against severe acute respiratory syndrome coronavirus 2 (SARS‑CoV‑2) provides a unique opportunity to study immunization across different platforms. In a single-center cohort, we analyzed the humoral and cellular immune compartments following five coronavirus disease 2019 (COVID-19) vaccines spanning three technologies (adenoviral, mRNA and inactivated virus) administered in 16 combinations. For adenoviral and inactivated-virus vaccines, heterologous combinations were generally more immunogenic compared to homologous regimens. The mRNA vaccine as the second dose resulted in the strongest antibody response and induced the highest frequency of spike-binding memory B cells irrespective of the priming vaccine. Priming with the inactivated-virus vaccine increased the SARS-CoV-2-specific T cell response, whereas boosting did not. Distinct immune signatures were elicited by the different vaccine combinations, demonstrating that the immune response is shaped by the type of vaccines applied and the order in which they are delivered. These data provide a framework for improving future vaccine strategies against pathogens and cancer.

Revival of the heterologous prime-boost technique in COVID-19: An outlook from the history of outbreaks

BACKGROUND

The heterologous prime-boost vaccination technique is not novel as it has a history of deployment in previous outbreaks.

AIM

Hence, this narrative review aims to provide critical insight for reviving the heterologous prime-boost immunization strategy for SARS-CoV-2 vaccination relative to a brief positive outlook on the mix-dose approach deployed in previous and existing outbreaks (ie, Ebola virus disease (EVD), malaria, tuberculosis, hepatitis B, HIV and influenza virus).

METHODOLOGY AND MATERIALS

A Boolean search was carried out to find the literature in MEDLINE-PubMed, Clinicaltrials, and Cochrane Central Register of Controlled Trials databases up till December 22, 2021, using the specific keywords that include "SARS-CoV2", "COVID-19", "Ebola," "Malaria," "Tuberculosis," "Human Immunodeficiency Virus," "Hepatitis B," "Influenza," "Mix and match," "Heterologous prime-boost," with interposition of "OR" and "AND." Full text of all the related articles in English language with supplementary appendix was retrieved. In addition, the full text of relevant cross-references was also retrieved.

RESULTS

Therefore, as generally evident by the primary outcomes, that is, safety, reactogenicity, and immunogenicity reported and updated by preclinical and clinical studies for addressing previous and existing outbreaks so far, including COVID-19, it is understood that heterologous prime-boost immunization has been proven successful for eliciting a more efficacious immune response as of yet in comparison to the traditional homologous prime-boost immunization regimen.

DISCUSSION

Accordingly, with increasing cases of COVID-19, many countries such as Germany, Pakistan, Canada, Thailand, and the United Kingdom have started administering the heterologous vaccination as the technique aids to rationalize the usage of the available vaccines to aid in the global race to vaccinate majority to curb the spread of COVID-19 efficiently. However, the article emphasizes the need for more large controlled trials considering demographic details of vaccine recipients, which would play an essential role in clearing the mistrust about safety concerns to pace up the acceptance of the technique across the globe.

CONCLUSION

Consequently, by combatting the back-to-back waves of COVID-19 and other challenging variants of concerns, including Omicron, the discussed approach can also help in addressing the expected evolution of priority outbreaks as coined by WHO, that is, "Disease X" in 2018 with competency, which according to WHO can turn into the "next pandemic" or the "next public health emergency," thus would eventually lead to eradicating the risk of "population crisis."

The potential of the CMB305 vaccine regimen to target NY-ESO-1 and improve outcomes for synovial sarcoma and myxoid/round cell liposarcoma patients

INTRODUCTION

Synovial Sarcoma (SS) and Myxoid Round Cell Liposarcoma (MRCL) are devastating sarcoma subtypes with few treatment options and poor outcomes in the advanced setting. However, both these diseases may be ideal for novel immunotherapies targeting the cancer-testis antigen, NY-ESO-1.

AREAS COVERED

In this review, we discuss the novel NY-ESO-1 targeted vaccine regimen, CMB305. This regimen uses a unique integration-deficient, dendritic-cell targeting lentiviral vector from the ZVex® platform, LV305, in order to prime NY-ESO-1 specific T cells. LV305 has single agent activity, and, in one case, caused a durable partial response in a refractory SS patient. CMB305 also includes a boost from a NY-ESO-1 protein vaccine given along with a potent toll-like-4 receptor agonist, glycopyranosyl lipid A. CMB305 induces NY-ESO-1 specific T cell responses in both SS and MRC patients and these patients had excellent overall survival (OS) outcomes in the initial phase I study.

EXPERT COMMENTARY

CMB305 is a therapeutic vaccine regimen targeting NY-ESO-1 based on the lentiviral vaccine vector, LV305. Phase I studies have proven this vaccine is active immunologically. Data suggesting this vaccine may improve OS for SS and MRCL patients is exciting but early, and on-going work is testing the impact of CMB305 on patient outcomes.

Potential biological targets ofBacillus anthracisin anti-infective approaches against the threat of bioterrorism

The terrorist attacks of 2001 involving anthrax underscore the imperative that safe and effective medical countermeasures should be readily available. Vaccination appears to be the most effective form of mass protection against a biological attack, but the current vaccines have drawbacks that justify the enormous amount of effort currently being put into developing more effective vaccines and other treatment modalities. After providing a comprehensive overview of the organism Bacillus anthracis as a biological weapon and its pathogenicity, this review briefly summarizes the current knowledge vital to the management of anthrax disease. This knowledge has been acquired since 2001 as a result of the progress on anthrax research and focuses on the possible development of improved human anti-infective strategies targeting B. anthracis spore components, as well as strategies based on host-pathogen interactions.

DNA immunization

DNA immunization was discovered in early 1990s, and its use has been expanded from vaccine studies to a broader range of biomedical research areas, such as the generation of high-quality polyclonal and monoclonal antibodies as research reagents. In this unit, three common DNA immunization methods are described: needle injection, electroporation, and gene gun. In addition, several common considerations related to DNA immunization are discussed.

Antigen engineering can play a critical role in the protective immunity elicited by Yersinia pestis DNA vaccines

The use of a DNA immunization approach to deliver protective antigens against Yersinia pestis (Y. pestis) has been successful in previously reported studies. In the current study, the gene designs for V and F1, two well-studied virulent factors serving as main targets for vaccine development, were altered to explore additional options in hopes of improving the protective immunity of DNA vaccines expressing these two antigens. Compared to the wild type V gene DNA vaccines, the use of codon optimized V gene sequences was effective in improving the antigen expression, titers of anti-V antibody responses, and survival against a mucosal lethal challenge. For the F1 DNA vaccine, removal of the N-terminal hydrophobic region was able to improve protective immunity. However, adding a mammalian signal peptide sequence to F1 actually led to reduced protection despite it inducing slightly higher anti-F1 antibody responses. The F1 gene can be fused with a gene coding for YscF, a newly confirmed partial protective antigen for Y. pestis, to produce DNA vaccines that express fused F1 and YscF antigens. One design, in particular, that had YscF fused to the downstream sequence of F1, produced better protection than separate F1 or YscF DNA vaccines, suggesting a potential synergistic effect between these two antigens. Findings from the above studies indicated that there are multiple approaches to optimize the protective immunity for plague DNA vaccines. Most importantly, proper antigen engineering to produce optimal antigen gene inserts in DNA vaccines can clearly play a major role in the future designs of a wide range of DNA vaccines.

Anthrax prevention and treatment: utility of therapy combining antibiotic plus vaccine

The intentional release of anthrax spores in 2001 confirmed this pathogen's ability to cause widespread panic, morbidity and mortality. While individuals exposed to anthrax can be successfully treated with antibiotics, pre-exposure vaccination can reduce susceptibility to infection-induced illness. Concern over the safety and immunogenicity of the licensed US vaccine (Anthrax Vaccine Adsorbed (AVA)) has fueled research into alternatives. Second-generation anthrax vaccines based on purified recombinant protective antigen (rPA) have entered clinical trials. These rPA vaccines induce neutralizing antibodies that prevent illness, but the magnitude and duration of the resultant protective response is modest. Efforts are underway to bolster the immunogenicity of rPA by combining it with adjuvants and other immunostimulatory agents. Third generation vaccines are under development that utilize a wide variety of immunization platforms, antigens, adjuvants, delivery methods and routes of delivery to optimize the induction of a protective immunity. For the foreseeable future, vaccination will rely on first and second generation vaccines co-administered with immune adjuvants. Optimal post-exposure treatment of immunologically naive individuals should include a combination of vaccine plus antibiotic therapy.

Technical transformation of biodefense vaccines

Biodefense vaccines are developed against a diverse group of pathogens. Vaccines were developed for some of these pathogens a long time ago but they are facing new challenges to move beyond the old manufacturing technologies. New vaccines to be developed against other pathogens have to determine whether to follow traditional vaccination strategies or to seek new approaches. Advances in basic immunology and recombinant DNA technology have fundamentally transformed the process of formulating a vaccine concept, optimizing protective antigens, and selecting the most effective vaccine delivery approach for candidate biodefense vaccines.

Heterologous prime-boost vaccination

An effective vaccine usually requires more than one time immunization in the form of prime-boost. Traditionally the same vaccines are given multiple times as homologous boosts. New findings suggested that prime-boost can be done with different types of vaccines containing the same antigens. In many cases such heterologous prime-boost can be more immunogenic than homologous prime-boost. Heterologous prime-boost represents a new way of immunization and will stimulate better understanding on the immunological basis of vaccines.

Transcriptomic basis for an antiserum against Micrurus corallinus (coral snake) venom

BACKGROUND

Micrurus corallinus (coral snake) is a tropical forest snake belonging to the family Elapidae. Its venom shows a high neurotoxicity associated with pre- and post-synaptic toxins, causing diaphragm paralysis, which may result in death. In spite of a relatively small incidence of accidents, serum therapy is crucial for those bitten. However, the adequate production of antiserum is hampered by the difficulty in obtaining sufficient amounts of venom from a small snake with demanding breeding conditions. In order to elucidate the molecular basis of this venom and to uncover possible immunogens for an antiserum, we generated expressed sequences tags (ESTs) from its venom glands and analyzed the transcriptomic profile. In addition, their immunogenicity was tested using DNA immunization.

RESULTS

A total of 1438 ESTs were generated and grouped into 611 clusters. Toxin transcripts represented 46% of the total ESTs. The two main toxin classes consisted of three-finger toxins (3FTx) (24%) and phospholipases A(2) (PLA(2)s) (15%). However, 8 other classes of toxins were present, including C-type lectins, natriuretic peptide precursors and even high-molecular mass components such as metalloproteases and L-amino acid oxidases. Each class included an assortment of isoforms, some showing evidence of alternative splicing and domain deletions. Five antigenic candidates were selected (four 3FTx and one PLA(2)) and used for a preliminary study of DNA immunization. The immunological response showed that the sera from the immunized animals were able to recognize the recombinant antigens.

CONCLUSION

Besides an improvement in our knowledge of the composition of coral snake venoms, which are very poorly known when compared to Old World elapids, the expression profile suggests abundant and diversified components that may be used in future antiserum formulation. As recombinant production of venom antigens frequently fails due to complex disulfide arrangements, DNA immunization may be a viable alternative. In fact, the selected candidates provided an initial evidence of the feasibility of this approach, which is less costly and not dependent on the availability of the venom.

A single-dose combination therapy that both prevents and treats anthrax infection

Exposure to anthrax leaves susceptible hosts at prolonged risk of infection since spores can persist in vivo for months before germinating to cause life-threatening disease. Anthrax vaccine adsorbed (AVA, the licensed US vaccine) induces immunity too slowly to protect susceptible individuals post-exposure. Antibiotics prevent the proliferation of vegetative bacilli but do not block latent spores from germinating. Thus, anthrax-exposed individuals must remain on antibiotic therapy for months to eliminate the threat posed by delayed spore germination. Unfortunately, long-term antibiotic treatment is poorly tolerated and frequently discontinued. This work explores whether administering a single dose of a long-acting antibiotic (Dalbavancin) combined with a rapidly immunogenic vaccine/adjuvant combination can provide seamless protection from anthrax with minimal patient compliance. Results show that significant protection is achieved by delivering a single dose of this therapeutic combination any time before through 3 days after anthrax exposure.

Bacillus anthracis: interactions with the host and establishment of inhalational anthrax

Due to its potential as a bioweapon, Bacillus anthracis has received a great deal of attention in recent years, and a significant effort has been devoted to understanding how this organism causes anthrax. There has been a particular focus on the inhalational form of the disease, and studies over the past several years have painted an increasingly complex picture of how B. anthracis enters the mammalian host, survives the host's defense mechanisms, disseminates throughout the body and causes death. This article reviews recent advances in these areas, with a focus on how the bacterium interacts with its host in establishing infection and causing anthrax.

Rapid generation of an anthrax immunotherapeutic from goats using a novel non-toxic muramyl dipeptide adjuvant

BACKGROUND

There is a clear need for vaccines and therapeutics for potential biological weapons of mass destruction and emerging diseases. Anthrax, caused by the bacterium Bacillus anthracis, has been used as both a biological warfare agent and bioterrorist weapon previously. Although antibiotic therapy is effective in the early stages of anthrax infection, it does not have any effect once exposed individuals become symptomatic due to B. anthracis exotoxin accumulation. The bipartite exotoxins are the major contributing factors to the morbidity and mortality observed in acute anthrax infections.

METHODS

Using recombinant B. anthracis protective antigen (PA83), covalently coupled to a novel non-toxic muramyl dipeptide (NT-MDP) derivative we hyper-immunized goats three times over the course of 14 weeks. Goats were plasmapheresed and the IgG fraction (not affinity purified) and F(ab')2 derivatives were characterized in vitro and in vivo for protection against lethal toxin mediated intoxication.

RESULTS

Anti-PA83 IgG conferred 100% protection at 7.5 mug in a cell toxin neutralization assay. Mice exposed to 5 LD50 of Bacillus anthracis Ames spores by intranares inoculation demonstrated 60% survival 14 d post-infection when administered a single bolus dose (32 mg/kg body weight) of anti-PA83 IgG at 24 h post spore challenge. Anti-PA83 F(ab')2 fragments retained similar neutralization and protection levels both in vitro and in vivo.

CONCLUSION

The protection afforded by these GMP-grade caprine immunotherapeutics post-exposure in the pilot murine model suggests they could be used effectively to treat post-exposure, symptomatic human anthrax patients following a bioterrorism event. These results also indicate that recombinant PA83 coupled to NT-MDP is a potent inducer of neutralizing antibodies and suggest it would be a promising vaccine candidate for anthrax. The ease of production, ease of covalent attachment, and immunostimulatory activity of the NT-MDP indicate it would be a superior adjuvant to alum or other traditional adjuvants in vaccine formulations.