Plague vaccine: recent progress and prospects

A bacteriophage cocktail targeting Yersinia pestis provides strong post-exposure protection in a rat pneumonic plague model

Yersinia pestis, one of the deadliest bacterial pathogens ever known, is responsible for three plague pandemics and several epidemics, with over 200 million deaths during recorded history. Due to high genomic plasticity, Y. pestis is amenable to genetic mutations as well as genetic engineering that can lead to the emergence or intentional development of pan-drug-resistant strains. Indeed, antibiotic-resistant strains (e.g., strains carrying multidrug-resistant or MDR plasmids) have been isolated in various countries and endemic areas. Thus, there is an urgent need to develop novel, safe, and effective treatment approaches for managing Y. pestis infections. This includes infections by antigenically distinct strains for which vaccines (none FDA approved yet) may not be effective and those that cannot be managed by currently available antibiotics. Lytic bacteriophages provide one such alternative approach. In this study, we examined post-exposure efficacy of a bacteriophage cocktail, YPP-401, to combat pneumonic plague caused by Y. pestis CO92. YPP-401 is a four-phage preparation effective against a panel of at least 68 genetically diverse Y. pestis strains. Using a pneumonic plague aerosol challenge model in gender-balanced Brown Norway rats, YPP-401 demonstrated ~88% protection when delivered 18 h post-exposure for each of two administration routes (i.e., intraperitoneal and intranasal) in a dose-dependent manner. Our studies provide proof-of-concept that YPP-401 could be an innovative, safe, and effective approach for managing Y. pestis infections, including those caused by naturally occurring or intentionally developed multidrug-resistant strains.IMPORTANCECurrently, there are no FDA-approved plague vaccines. Since antibiotic-resistant strains of Y. pestis have emerged or are being intentionally developed to be used as a biothreat agent, new treatment modalities are direly needed. Phage therapy provides a viable option against potentially antibiotic-resistant strains. Additionally, phages are nontoxic and have been approved by the FDA for use in the food industry. Our study provides the first evidence of the protective effect of a cocktail of four phages against pneumonic plague, the most severe form of disease. When treatment was initiated 18 h post infection by either the intranasal or intraperitoneal route in Brown Norway rats, up to 87.5% protection was observed. The phage cocktail had a minimal impact on a representative human microbiome panel, unlike antibiotics. This study provides strong proof-of-concept data for the further development of phage-based therapy to treat plague.

Nanodisc assembly from bacterial total lipid extracts

Nanodiscs are discoidal lipoproteins that have often been used as vehicles to study membrane proteins in their native configuration. Nanodiscs have been primarily made from synthetic lipids. However, nanodiscs also offer a format by which native lipids can be studied in their natural configuration. Here, we present a method to synthesize nanodiscs from bacterial total lipid extracts using the biothreat agent, Yersinia pestis, as a proof-of-concept. The creation of nanoparticles entirely composed of bacterial lipids supports membrane characterization and vaccine antigen discovery without the inherent safety concerns associated with live bacterial cells of this Tier 1 select agent pathogen.

Delivery of Yersinia pestis antigens via Escherichia coli outer membrane vesicles offered improved protection against plague

Outer membrane vesicles (OMVs) from Gram-negative bacteria can be used as a vaccine platform to deliver heterologous antigens. Here, the major protective antigens of Yersinia pestis, F1 and LcrV, were fused either with the leader sequence or the transmembrane domain of the outer membrane protein A (OmpA), resulting in chimeric proteins OmpA-ls-F1V and OmpA46-159-F1V, respectively. We show that OmpA-ls-F1V and OmpA46-159-F1V can be successfully delivered into the lumen and membrane of the OMVs of Escherichia coli, respectively. Mutation of ompA but not tolR in E. coli enhanced the delivery efficiency of OmpA-ls-F1V into OMVs. The OmpA-ls-F1V protein comprises up to 20% of the total protein in OMVs derived from the ompA mutant (OMVdA-ALS-F1V), a proportion significantly higher than the 1% observed for OmpA46-159-F1V in OMVs produced by an ompA mutant that expresses OmpA46-159-F1V, referred to as OMVdA-LATM5-F1V. Intramuscular (i.m.) immunization of mice with OMVdA-ALS-F1V induced significantly higher levels of serum anti-LcrV and anti-F1 IgG, and provided higher efficacy in protection against subcutaneous (s.c.) Y. pestis infection compared to OMVdA-LATM5-F1V and the purified recombinant F1V (rF1V) protein adsorbed to aluminum hydroxide. The three-dose i.m. immunization with OMVdA-ALS-F1V, administered at 14-day intervals, provides complete protection to mice against s.c. infection with 130 LD50 of Y. pestis 201 and conferred 80% against intranasal (i.n.) challenge with 11.4 LD50 of Y. pestis 201. Taken together, our findings indicate that the engineered OMVs containing F1V fused with the leader sequence of OmpA provide significantly higher protection than rF1V against both s.c. and i.n. infection of Y. pestis and more balanced Th1/Th2 responses.IMPORTANCEThe two major protective antigens of Y. pestis, LcrV and F1, have demonstrated the ability to elicit systemic and local mucosal immune responses as subunit vaccines. However, these vaccines have failed to provide adequate protection against pneumonic plague in African green monkeys. Here, Y. pestis F1 and LcrV antigens were successfully incorporated into the lumen and the surface of the outer membrane vesicles (OMVs) of E. coli by fusion either with the leader sequence or the transmembrane domain of OmpA. We compared the humoral immune response elicited by these OMV formulations and their protective efficacy in mice against Y. pestis. Our results demonstrate that the plague OMV vaccine candidates can induce robust protective immunity against both s.c. and i.n. Y. pestis infections, surpassing the effectiveness of rF1V. In addition, immunization with OMVs generated a relatively balanced Th1/Th2 immune response compared to rF1V immunization. These findings underscore the potential of OMVs-based plague vaccines for further development.

Progress on the research and development of plague vaccines with a call to action

There is a compelling demand for approved plague vaccines due to the endemicity of Yersinia pestis and its potential for pandemic spread. Whilst substantial progress has been made, we recommend that the global funding and health security systems should work urgently to translate some of the efficacious vaccines reviewed herein to expedite clinical development and to prevent future disastrous plague outbreaks, particularly caused by antimicrobial resistant Y. pestis strains.Content includes material subject to Crown Copyright © 2024.This is an open access article under the Open Government License ( http://www.nationalarchives.gov.uk/doc/open-government-licence/version/3/ ).

Advancing Vaccinology Capacity: Education and Efforts in Vaccine Development and Manufacturing across Africa

Africa, home to the world's second-largest population of approximately 1.3 billion, grapples with significant challenges in meeting its medical needs, particularly in accessing quality healthcare services and products. The continent faces a continuous onslaught of emerging infectious diseases, exacerbating the strain on its already fragile public health infrastructure. The COVID-19 crisis highlighted the urgency to build local vaccine production capacity and strengthen the health infrastructure in general. The risks associated with a heavy reliance on imported vaccines were exposed during the COVID-19 pandemic, necessitating the need to nurture and strengthen the local manufacturing of vaccines and therapeutic biologics. Various initiatives addressing training, manufacturing, and regulatory affairs are underway, and these require increasing dedicated and purposeful financial investment. Building vaccine manufacturing capacity requires substantial investment in training and infrastructure. This manuscript examines the current state of education in vaccinology and related sciences in Africa. It also provides an overview of the continent's efforts to address educational needs in vaccine development and manufacturing. Additionally, it evaluates the initiatives aimed at strengthening vaccine education and literacy, highlighting successful approaches and ongoing challenges. By assessing the progress made and identifying the remaining obstacles, this review offers insights into how Africa can enhance its vaccine manufacturing capacity to respond to vaccine-preventable disease challenges.

Antimicrobial therapies administrated during the Third Plague Pandemic in Europe

Plague raged in Europe for over 1400 years and was responsible for three major pandemics. Today, plague still poses a serious threat to global public health and surveillance is imperative. Plague is still present in natural reservoirs on several continents, including Africa, Asia and the Americas, and sometimes causes local cases and epidemics. The Third Plague Pandemic caused millions of deaths worldwide, including in Europe. Plague arrived in Europe in the autumn of 1896 mostly through maritime trade routes, where it spread with several epidemic events until 1945, when, in the port city of Taranto, the last known outbreak was recorded. In this paper, we present an overview of the natural history and pathogenicity of Yersinia pestis, the bacterium responsible for plague, its spread from Asia to Europe during the Third Pandemic, and the therapies used to treat and prevent the disease in Europe, with particular focus on the case of Taranto. In Taranto, the Pasteur Institute's antiserum antimicrobial therapy, and vaccination were used to treat and stop the advance of the bacterium, with mixed results.

Decrypting the multi-genome data for chimeric vaccine designing against the antibiotic resistant Yersinia pestis

Yersinia pestis, the causative agent of plague, is a gram-negative bacterium that can be fatal if not treated properly. Three types of plague are currently known: bubonic, septicemic, and pneumonic plague, among which the fatality rate of septicemic and pneumonic plague is very high. Bubonic plague can be treated, but only if antibiotics are used at the initial stage of the infection. But unfortunately, Y. pestis has also shown resistance to certain antibiotics such as kanamycin, minocycline, tetracycline, streptomycin, sulfonamides, spectinomycin, and chloramphenicol. Despite tremendous progress in vaccine development against Y. pestis, there is no proper FDA-approved vaccine available to protect people from its infections. Therefore, effective broad-spectrum vaccine development against Y. pestis is indispensable. In this study, vaccinomics-assisted immunoinformatics techniques were used to find possible vaccine candidates by utilizing the core proteome prepared from 58 complete genomes of Y. pestis. Human non-homologous, pathogen-essential, virulent, and extracellular and membrane proteins are potential vaccine targets. Two antigenic proteins were prioritized for the prediction of lead epitopes by utilizing reverse vaccinology approaches. Four vaccine designs were formulated using the selected B- and T-cell epitopes coupled with appropriate linkers and adjuvant sequences capable of inducing potent immune responses. The HLA allele population coverage of the T-cell epitopes selected for vaccine construction was also analyzed. The V2 constructs were top-ranked and selected for further analysis on the basis of immunological, physicochemical, and immune-receptor docking interactions and scores. Docking and molecular dynamic simulations confirmed the stability of construct V2 interactions with the host immune receptors. Immune simulation analysis anticipated the strong immune profile of the prioritized construct. In silico restriction cloning ensured the feasible cloning ability of the V2 construct in the expression system of E. coli strain K12. It is anticipated that the designed vaccine construct may be safe, effective, and able to elicit strong immune responses against Y. pestis infections and may, therefore, merit investigation using in vitro and in vivo assays.

Pneumonic Plague Protection Induced by a Monophosphoryl Lipid A Decorated Yersinia Outer-Membrane-Vesicle Vaccine

A new Yersinia pseudotuberculosis mutant strain, YptbS46, carrying the lpxE insertion and pmrF-J deletion is constructed and shown to exclusively produce monophosphoryl lipid A (MPLA) having adjuvant properties. Outer membrane vesicles (OMVs) isolated from YptbS46 harboring an lcrV expression plasmid, pSMV13, are designated OMV46-LcrV, which contained MPLA and high amounts of LcrV (Low Calcium response V) and displayed low activation of Toll-like receptor 4 (TLR4). Intramuscular prime-boost immunization with 30 µg of of OMV46-LcrV exhibited substantially reduced reactogenicity than the parent OMV44-LcrV and conferred complete protection to mice against a high-dose of respiratory Y. pestis challenge. OMV46-LcrV immunization induced robust adaptive responses in both lung mucosal and systemic compartments and orchestrated innate immunity in the lung, which are correlated with rapid bacterial clearance and unremarkable lung damage during Y. pestis challenge. Additionally, OMV46-LcrV immunization conferred long-term protection. Moreover, immunization with reduced doses of OMV46-LcrV exhibited further lower reactogenicity and still provided great protection against pneumonic plague. The studies strongly demonstrate the feasibility of OMV46-LcrV as a new type of plague vaccine candidate.

A Bacteriophage Cocktail Targeting Yersinia pestis Provides Strong Post-Exposure Protection in a Rat Pneumonic Plague Model

Yersinia pestis , one of the deadliest bacterial pathogens ever known, is responsible for three plague pandemics and several epidemics, with over 200 million deaths during recorded history. Due to high genomic plasticity, Y. pestis is amenable to genetic mutations as well as genetic engineering that can lead to the emergence or intentional development of pan-drug resistant strains. The dissemination of such Y. pestis strains could be catastrophic, with public health consequences far more daunting than those caused by the recent COVID-19 pandemic. Thus, there is an urgent need to develop novel, safe, and effective treatment approaches for managing Y. pestis infections. This includes infections by antigenically distinct strains for which vaccines, none FDA approved yet, may not be effective, and those that cannot be controlled by approved antibiotics. Lytic bacteriophages provide one such alternative approach. In this study, we examined post-exposure efficacy of a bacteriophage cocktail, YPP-401, to combat pneumonic plague caused by Y. pestis CO92. YPP-401 is a four-phage preparation with a 100% lytic activity against a panel of 68 genetically diverse Y. pestis strains. Using a pneumonic plague aerosol challenge model in gender-balanced Brown Norway rats, YPP-401 demonstrated ∼88% protection when delivered 18 hours post-exposure for each of two administration routes (i.e., intraperitoneal and intranasal) in a dose-dependent manner. Our studies suggest that YPP-401 could provide an innovative, safe, and effective approach for managing Y. pestis infections, including those caused by naturally occurring or intentionally developed strains that cannot be managed by vaccines in development and antibiotics.

A self-amplifying RNA vaccine provides protection in a murine model of bubonic plague

Mice were immunized with a combination of self-amplifying (sa) RNA constructs for the F1 and V antigens of Yersinia pestis at a dose level of 1 μg or 5 μg or with the respective protein sub-units as a reference vaccine. The immunization of outbred OF1 mice on day 0 and day 28 with the lowest dose used (1 μg) of each of the saRNA constructs in lipid nanoparticles protected 5/7 mice against subsequent sub-cutaneous challenge on day 56 with 180 cfu (2.8 MLD) of a 2021 clinical isolate of Y. pestis termed 10-21/S whilst 5/7 mice were protected against 1800cfu (28MLD) of the same bacteria on day 56. By comparison, only 1/8 or 1/7 negative control mice immunized with 10 μg of irrelevant haemagglutin RNA in lipid nanoparticles (LNP) survived the challenge with 2.8 MLD or 28 MLD Y. pestis 10-21/S, respectively. BALB/c mice were also immunized with the same saRNA constructs and responded with the secretion of specific IgG to F1 and V, neutralizing antibodies for the V antigen and developed a recall response to both F1 and V. These data represent the first report of an RNA vaccine approach using self-amplifying technology and encoding both of the essential virulence antigens, providing efficacy against Y. pestis. This saRNA vaccine for plague has the potential for further development, particularly since its amplifying nature can induce immunity with less boosting. It is also amenable to rapid manufacture with simpler downstream processing than protein sub-units, enabling rapid deployment and surge manufacture during disease outbreaks.

The efficacy, safety, and immunogenicity of plague vaccines: A systematic literature review

Plague remains endemic in many parts of the world, and despite efforts, no preventative vaccine is available. We performed a systemic review of available randomised controlled trials (RCTs) of live, attenuated, or killed plague vaccines vs. placebo, no intervention, or other plague vaccine to evaluate their efficacy, safety, and immunogenicity. Data sources included MEDLINE, Embase, and the Cochrane Library; clinical trial registers; and reference lists of included studies. Primary outcomes were efficacy, safety, and immunogenicity. Risk of bias was assessed using the Cochrane Collaborations tool. Only 2 RCTs, both on subunit vaccines, were included out of the 75 screened articles. The 2 trials included 240 participants with a follow-up of 3 months and 60 participants with a follow-up of 13 months, respectively. Safety evidence was limited, but both vaccines were well tolerated, with only mild to moderate adverse events. Both vaccines were immunogenic in a dose-dependent manner. However, given the limited data identified in this systematic review, we are unable to quantify the efficacy of vaccines to prevent plague, as well as their long-term safety and immunogenicity. More trials of plague vaccines are needed to generate additional evidence of their long-term effects.

Pneumonic plague protection induced by a monophosphoryl lipid A decorated Yersinia outer-membrane-vesicle vaccine

A newly constructed Yersinia pseudotuberculosis mutant (YptbS46) carrying the lpxE insertion and pmrF-J deletion exclusively synthesized an adjuvant form of lipid A, monophosphoryl lipid A (MPLA). Outer membrane vesicles (OMVs) isolated from YptbS46 harboring an lcrV expression plasmid, pSMV13, were designated OMV 46 -LcrV, which contained MPLA and high amounts of LcrV and displayed low activation of Toll-like receptor 4 (TLR4). Similar to the previous OMV 44 -LcrV, intramuscular prime-boost immunization with 30 µg of OMV 46 -LcrV exhibited substantially reduced reactogenicity and conferred complete protection to mice against a high-dose of respiratory Y. pestis challenge. OMV 46 -LcrV immunization induced robust adaptive responses in both lung mucosal and systemic compartments and orchestrated innate immunity in the lung, which were correlated with rapid bacterial clearance and unremarkable lung damage during Y. pestis challenge. Additionally, OMV 46 -LcrV immunization conferred long-term protection. Moreover, immunization with reduced doses of OMV 46 -LcrV exhibited further lower reactogenicity and still provided great protection against pneumonic plague. Our studies strongly demonstrate the feasibility of OMV 46 -LcrV as a new type of plague vaccine candidate.

Interplays of mutations in waaA, cmk, and ail contribute to phage resistance in Yersinia pestis

Plague caused by Yersinia pestis remains a public health threat worldwide. Because multidrug-resistant Y. pestis strains have been found in both humans and animals, phage therapy has attracted increasing attention as an alternative strategy against plague. However, phage resistance is a potential drawback of phage therapies, and the mechanism of phage resistance in Y. pestis is yet to be investigated. In this study, we obtained a bacteriophage-resistant strain of Y. pestis (S56) by continuously challenging Y. pestis 614F with the bacteriophage Yep-phi. Genome analysis identified three mutations in strain S56: waaA* (9-bp in-frame deletion ₂₄₉GTCATCGTG₂₅₇), cmk* (10-bp frameshift deletion ₁₅CCGGTGATAA₂₄), and ail* (1-bp frameshift deletion A₅₃₈). WaaA (3-deoxy-D-manno-octulosonic acid transferase) is a key enzyme in lipopolysaccharide biosynthesis. The waaA* mutation leads to decreased phage adsorption because of the failure to synthesize the lipopolysaccharide core. The mutation in cmk (encoding cytidine monophosphate kinase) increased phage resistance, independent of phage adsorption, and caused in vitro growth defects in Y. pestis. The mutation in ail inhibited phage adsorption while restoring the growth of the waaA null mutant and accelerating the growth of the cmk null mutant. Our results confirmed that mutations in the WaaA-Cmk-Ail cascade in Y. pestis contribute to resistance against bacteriophage. Our findings help in understanding the interactions between Y. pestis and its phages.

[The role of the pulmonologist in an armed conflict]

INTRODUCTION

Recent news points to the eventuality of an armed conflict on the national territory.

STATE OF THE ART

In this situation, pulmonologists will in all likelihood have a major role to assume in caring for the injured, especially insofar as chest damage is a major cause of patient death.

PERSPECTIVES

The main injuries that pulmonologists may be called upon to treat stem not only from explosions, but also from chemical, biological and nuclear hazards. In this article, relevant organizational and pedagogical aspects are addressed. Since exhaustiveness on this subject is unattainable, we are proposing training on specific subjects for interested practitioners.

CONCLUSION

The resilience of the French health system in a situation of armed conflict depends on the active participation of all concerned parties. With this in mind, it is of prime importance that the pneumological community be sensitized to the potential predictable severity of war-related injuries.

Lung Resident Memory T Cells Activated by Oral Vaccination Afford Comprehensive Protection against Pneumonic Yersinia pestis Infection

A growing body of evidence has shown that resident memory T (TRM) cells formed in tissue after mucosal infection or vaccination are crucial for counteracting reinfection by pathogens. However, whether lung TRM cells activated by oral immunization with Yptb1(pYA5199) play a protective role against pneumonic plague remains unclear. In this study, we demonstrated that lung CD4+ and CD8+ TRM cells significantly accumulated in the lungs of orally Yptb1(pYA5199)-vaccinated mice and dramatically expanded with elevated IL-17A, IFN-γ, and/or TNF-α production after pulmonary Yersinia pestis infection and afforded significant protection. Short-term or long-term treatment of immunized mice with FTY720 did not affect lung TRM cell formation and expansion or protection against pneumonic plague. Moreover, the intratracheal transfer of both lung CD4+ and CD8+ TRM cells conferred comprehensive protection against pneumonic plague in naive recipient mice. Lung TRM cell-mediated protection was dramatically abolished by the neutralization of both IFN-γ and IL-17A. Our findings reveal that lung TRM cells can be activated via oral Yptb1(pYA5199) vaccination, and that IL-17A and IFN-γ production play an essential role in adaptive immunity against pulmonary Y. pestis infection. This study highlights an important new target for developing an effective pneumonic plague vaccine.

Diversity in Genetic Regulation of Bacterial Fimbriae Assembled by the Chaperone Usher Pathway

Bacteria express different types of hair-like proteinaceous appendages on their cell surface known as pili or fimbriae. These filamentous structures are primarily involved in the adherence of bacteria to both abiotic and biotic surfaces for biofilm formation and/or virulence of non-pathogenic and pathogenic bacteria. In pathogenic bacteria, especially Gram-negative bacteria, fimbriae play a key role in bacteria-host interactions which are critical for bacterial invasion and infection. Fimbriae assembled by the Chaperone Usher pathway (CUP) are widespread within the Enterobacteriaceae, and their expression is tightly regulated by specific environmental stimuli. Genes essential for expression of CUP fimbriae are organised in small blocks/clusters, which are often located in proximity to other virulence genes on a pathogenicity island. Since these surface appendages play a crucial role in bacterial virulence, they have potential to be harnessed in vaccine development. This review covers the regulation of expression of CUP-assembled fimbriae in Gram-negative bacteria and uses selected examples to demonstrate both dedicated and global regulatory mechanisms.

<i>In silico</i> Research at the Stages of Designing Modern Means for Prevention of Plague (by the Example of Subunit Vaccines)

The purpose of this review was to analyze the findings of domestic and foreign researchers on the development of modern drugs for the specific prevention of plague and to illustrate the possibilities of using bioinformatics analysis at the design stages to create an effective and safe vaccine. Work on the creation of an effective new-generation plague vaccine is hampered by several factors associated primarily with the presence of mechanisms of evasion from the immune system of the macroorganism, as well as a large number of pathogenicity determinants in the plague agent. Due to the development of approaches that are based on in silico studies, there is a progressive development of vaccine technologies oriented primarily to the use of the most important immunogens of the plague microbe (F1 and V antigen). Studies aimed at improving the antigenic properties of F1 and LcrV, as well as work on bioinformatic search and analysis of additional promising components to be included in the composition of subunit vaccines are considered as topical applications of bioinformatics data analysis in developing the tools for enhancing the effectiveness of protection through vaccination with subunit preparations.

The magnitude of the germinal center B cell and T follicular helper cell response predicts long-lasting antibody titers to plague vaccination

The development of a safe and effective vaccine against Yersinia pestis, the causative organism for plague disease, remains an important global health priority. Studies have demonstrated effective immune-based protection against plague challenge that is induced by plague antigen subunit vaccination in an aqueous alhydrogel formulation; however, whether these candidate vaccines in this formulation and presentation, induce long-lasting immunological memory in the form of durable cellular and antibody recall responses has not been fully demonstrated. In this study, we analyzed germinal center T follicular helper and germinal center B cell responses following F1V and F1 + V plague subunit immunization of mice with vaccines formulated in various adjuvants. Our data demonstrate that recombinant plague protein immunization formulated with IL-2/GM-CSF cytokines bound to alhydrogel adjuvant drive an increase in the magnitude of the germinal center T follicular helper and germinal center B cell responses following primary immunization, compared to vaccines formulated with Alhydrogel adjuvant alone. In contrast, plague protein subunit immunization combined with CpG ODN bound to alhydrogel increased the magnitude and duration of the germinal center Tfh and B cell responses following booster immunization. Importantly, enhanced germinal center Tfh and B cell responses correlated with long-lasting and high F1V-specific antibody titers and more robust antibody recall responses to F1V re-exposure. These findings indicate that vaccine formulations that drive enhancement of the germinal center Tfh and B cell responses are critical for inducing durable plague-specific humoral immunity.

A Historical Review of Military Medical Strategies for Fighting Infectious Diseases: From Battlefields to Global Health

The environmental conditions generated by war and characterized by poverty, undernutrition, stress, difficult access to safe water and food as well as lack of environmental and personal hygiene favor the spread of many infectious diseases. Epidemic typhus, plague, malaria, cholera, typhoid fever, hepatitis, tetanus, and smallpox have nearly constantly accompanied wars, frequently deeply conditioning the outcome of battles/wars more than weapons and military strategy. At the end of the nineteenth century, with the birth of bacteriology, military medical researchers in Germany, the United Kingdom, and France were active in discovering the etiological agents of some diseases and in developing preventive vaccines. Emil von Behring, Ronald Ross and Charles Laveran, who were or served as military physicians, won the first, the second, and the seventh Nobel Prize for Physiology or Medicine for discovering passive anti-diphtheria/tetanus immunotherapy and for identifying mosquito Anopheline as a malaria vector and plasmodium as its etiological agent, respectively. Meanwhile, Major Walter Reed in the United States of America discovered the mosquito vector of yellow fever, thus paving the way for its prevention by vector control. In this work, the military relevance of some vaccine-preventable and non-vaccine-preventable infectious diseases, as well as of biological weapons, and the military contributions to their control will be described. Currently, the civil-military medical collaboration is getting closer and becoming interdependent, from research and development for the prevention of infectious diseases to disasters and emergencies management, as recently demonstrated in Ebola and Zika outbreaks and the COVID-19 pandemic, even with the high biocontainment aeromedical evacuation, in a sort of global health diplomacy.

Protection Induced by Oral Vaccination with a Recombinant Yersinia pseudotuberculosis Delivering Yersinia pestis LcrV and F1 Antigens in Mice and Rats against Pneumonic Plague

A newly attenuated Yersinia pseudotuberculosis strain (designated Yptb1) with triple mutation Δasd ΔyopK ΔyopJ and chromosomal insertion of the Y. pestis caf1R-caf1M-caf1A-caf1 operon was constructed as a live vaccine platform. Yptb1 tailored with an Asd⁺ plasmid (pYA5199) (designated Yptb1[pYA5199]) simultaneously delivers Y. pestis LcrV and F1. The attenuated Yptb1(pYA5199) localized in the Peyer's patches, lung, spleen, and liver for a few weeks after oral immunization without causing any disease symptoms in immunized rodents. An oral prime-boost Yptb1(pYA5199) immunization stimulated potent antibody responses to LcrV, F1, and Y. pestis whole-cell lysate (YPL) in Swiss Webster mice and Brown Norway rats. The prime-boost Yptb1(pYA5199) immunization induced higher antigen-specific humoral and cellular immune responses in mice than a single immunization did, and it provided complete short-term and long-term protection against a high dose of intranasal Y. pestis challenge in mice. Moreover, the prime-boost immunization afforded substantial protection for Brown Norway rats against an aerosolized Y. pestis challenge. Our study highlights that Yptb1(pYA5199) has high potential as an oral vaccine candidate against pneumonic plague.

Perception of Professionals from Different Healthcare Units Regarding the Use of Spray Technology for the Instantaneous Decontamination of Personal Protective Equipment during the Coronavirus Disease Pandemic: A Short Analysis

Within the context of the coronavirus disease (COVID-19) pandemic, different disinfection technologies have been developed to efficiently exercise microbial control, especially to minimize the potential risks that are associated with transmission and infection among healthcare professionals. Thus, the aim of this work was to evaluate the perception of professionals regarding the use of a new technology (chamber) for the instantaneous decontamination of personal protective equipment before the doffing stage. This was a cross-sectional descriptive study where the study data were obtained by using a questionnaire with qualitative questions. In total, 245 professionals participated in the study in three hospitals. Healthcare professionals represented 72.24% (n = 177) of the investigated sample. Approximately 69% of the professionals considered the disinfection chamber as a safe technology, and 75.10% considered it as an important and effective protective barrier for healthcare professionals in view of its application before the doffing process. The results found in this study demonstrate that the use of spray technology in the stage prior to the doffing process is acceptable to professionals, and that it can be an important tool for ensuring the additional protection of the professionals who work directly with patients who are diagnosed with COVID-19.

Recent Trends in Protective Textiles against Biological Threats: A Focus on Biological Warfare Agents

The rising threats to worldwide security (affecting the military, first responders, and civilians) urge us to develop efficient and versatile technological solutions to protect human beings. Soldiers, medical personnel, firefighters, and law enforcement officers should be adequately protected, so that their exposure to biological warfare agents (BWAs) is minimized, and infectious microorganisms cannot be spread so easily. Current bioprotective military garments include multilayered fabrics integrating activated carbon as a sorptive agent and a separate filtrating layer for passive protection. However, secondary contaminants emerge following their accumulation within the carbon filler. The clothing becomes too heavy and warm to wear, not breathable even, preventing the wearer from working for extended hours. Hence, a strong need exists to select and/or create selectively permeable layered fibrous structures with bioactive agents that offer an efficient filtering capability and biocidal skills, ensuring lightweightness, comfort, and multifunctionality. This review aims to showcase the main possibilities and trends of bioprotective textiles, focusing on metal-organic frameworks (MOFs), inorganic nanoparticles (e.g., ZnO-based), and organic players such as chitosan (CS)-based small-scale particles and plant-derived compounds as bioactive agents. The textile itself should be further evaluated as the foundation for the barrier effect and in terms of comfort. The outputs of a thorough, standardized characterization should dictate the best elements for each approach.

Remodeling Yersinia pseudotuberculosis to generate a highly immunogenic outer membrane vesicle vaccine against pneumonic plague

SignificanceYersinia pestis, the etiologic agent of plague, has been responsible for high mortality in several epidemics throughout human history. This plague bacillus has been used as a biological weapon during human history and is currently one of the deadliest biological threats. Currently, no licensed plague vaccines are available in the Western world. Since an array of immunogens are enclosed in outer membrane vesicles (OMVs), immune responses elicited by OMVs against a diverse range of antigens may reduce the likelihood of antigen circumvention. Therefore, self-adjuvanting OMVs from a remodeled Yersinia pseudotuberculosis strain as a type of plague vaccine could diversify prophylactic choices and solve current vaccine limitations.

Non-Canonical Host Intracellular Niche Links to New Antimicrobial Resistance Mechanism

Globally, infectious diseases are one of the leading causes of death among people of all ages. The development of antimicrobials to treat infectious diseases has been one of the most significant advances in medical history. Alarmingly, antimicrobial resistance is a widespread phenomenon that will, without intervention, make currently treatable infections once again deadly. In an era of widespread antimicrobial resistance, there is a constant and pressing need to develop new antibacterial drugs. Unraveling the underlying resistance mechanisms is critical to fight this crisis. In this review, we summarize some emerging evidence of the non-canonical intracellular life cycle of two priority antimicrobial-resistant bacterial pathogens: Pseudomonas aeruginosa and Staphylococcus aureus. The bacterial factors that modulate this unique intracellular niche and its implications in contributing to resistance are discussed. We then briefly discuss some recent research that focused on the promises of boosting host immunity as a combination therapy with antimicrobials to eradicate these two particular pathogens. Finally, we summarize the importance of various strategies, including surveillance and vaccines, in mitigating the impacts of antimicrobial resistance in general.

Predictors of Survival after Vaccination in a Pneumonic Plague Model

Background: The need for an updated plague vaccine is highlighted by outbreaks in endemic regions together with the pandemic potential of this disease. There is no easily available, approved vaccine. Methods: Here we have used a murine model of pneumonic plague to examine the factors that maximise immunogenicity and contribute to survival following vaccination. We varied vaccine type, as either a genetic fusion of the F1 and V protein antigens or a mixture of these two recombinant antigens, as well as antigen dose-level and formulation in order to correlate immune response to survival. Results: Whilst there was interaction between each of the variables of vaccine type, dose level and formulation and these all contributed to survival, vaccine formulation in protein-coated microcrystals (PCMCs) was the key contributor in inducing antibody titres. From these data, we propose a cut-off in total serum antibody titre to the F1 and V proteins of 100 µg/mL and 200 µg/mL, respectively. At these thresholds, survival is predicted in this murine pneumonic model to be >90%. Within the total titre of antibody to the V antigen, the neutralising antibody component correlated with dose level and was enhanced when the V antigen in free form was formulated in PCMCs. Antibody titre to F1 was limited by fusion to V, but this was compensated for by PCMC formulation. Conclusions: These data will enable clinical assessment of this and other candidate plague vaccines that utilise the same vaccine antigens by identifying a target antibody titre from murine models, which will guide the evaluation of clinical titres as serological surrogate markers of efficacy.

Peptidoglycan-Free Bacterial Ghosts Confer Enhanced Protection against Yersinia pestis Infection

To develop a modern plague vaccine, we used hypo-endotoxic Yersinia&nbsp;pestis bacterial ghosts (BGs) with combinations of genes encoding the bacteriophage ɸX174 lysis-mediating protein E and/or holin-endolysin systems from λ or L-413C phages. Expression of the protein E gene resulted in the BGs that retained the shape of the original bacterium. Co-expression of this gene with genes coding for holin-endolysin system of the phage L-413C caused formation of structures resembling collapsed sacs. Such structures, which have lost their rigidity, were also formed as a result of the expression of only the L-413C holin-endolysin genes. A similar holin-endolysin system from phage λ containing mutated holin gene S and intact genes R-Rz coding for the endolysins caused generation of mixtures of BGs that had (i) practically preserved and (ii) completely lost their original rigidity. The addition of protein E to the work of this system shifted the equilibrium in the mixture towards the collapsed sacs. The collapse of the structure of BGs can be explained by endolysis of peptidoglycan sacculi. Immunizations of laboratory animals with the variants of BGs followed by infection with a wild-type Y. pestis strain showed that bacterial envelopes protected only cavies. BGs with maximally hydrolyzed peptidoglycan had a greater protectivity compared to BGs with a preserved peptidoglycan skeleton.

Facilitating Antiviral Drug Discovery Using Genetic and Evolutionary Knowledge

Over the course of human history, billions of people worldwide have been infected by various viruses. Despite rapid progress in the development of biomedical techniques, it is still a significant challenge to find promising new antiviral targets and drugs. In the past, antiviral drugs mainly targeted viral proteins when they were used as part of treatment strategies. Since the virus mutation rate is much faster than that of the host, such drugs feature drug resistance and narrow-spectrum antiviral problems. Therefore, the targeting of host molecules has gradually become an important area of research for the development of antiviral drugs. In recent years, rapid advances in high-throughput sequencing techniques have enabled numerous genetic studies (such as genome-wide association studies (GWAS), clustered regularly interspersed short palindromic repeats (CRISPR) screening, etc.) for human diseases, providing valuable genetic and evolutionary resources. Furthermore, it has been revealed that successful drug targets exhibit similar genetic and evolutionary features, which are of great value in identifying promising drug targets and discovering new drugs. Considering these developments, in this article the authors propose a host-targeted antiviral drug discovery strategy based on knowledge of genetics and evolution. We first comprehensively summarized the genetic, subcellular location, and evolutionary features of the human genes that have been successfully used as antiviral targets. Next, the summarized features were used to screen novel druggable antiviral targets and to find potential antiviral drugs, in an attempt to promote the discovery of new antiviral drugs.

Plague Prevention and Therapy: Perspectives on Current and Future Strategies

Plague, caused by the bacterial pathogen Yersinia pestis, is a vector-borne disease that has caused millions of human deaths over several centuries. Presently, human plague infections continue throughout the world. Transmission from one host to another relies mainly on infected flea bites, which can cause enlarged lymph nodes called buboes, followed by septicemic dissemination of the pathogen. Additionally, droplet inhalation after close contact with infected mammals can result in primary pneumonic plague. Here, we review research advances in the areas of vaccines and therapeutics for plague in context of Y. pestis virulence factors and disease pathogenesis. Plague continues to be both a public health threat and a biodefense concern and we highlight research that is important for infection mitigation and disease treatment.

Yersinia pseudotuberculosis YopJ Limits Macrophage Response by Downregulating COX-2-Mediated Biosynthesis of PGE2 in a MAPK/ERK-Dependent Manner

Prostaglandin E2 (PGE2) is an essential immunomodulatory lipid released by cells in response to infection with many bacteria, yet its function in macrophage-mediated bacterial clearance is poorly understood. Yersinia overall inhibits the inflammatory circuit, but its effect on PGE2 production is unknown. We hypothesized that one of the Yersinia effector proteins is responsible for the inhibition of PGE2 biosynthesis. We identified that yopB-deficient Y. enterocolitica and Y. pseudotuberculosis deficient in the secretion of virulence proteins via a type 3 secretion system (T3SS) failed to inhibit PGE2 biosynthesis in macrophages. Consistently, COX-2-mediated PGE2 biosynthesis is upregulated in cells treated with heat-killed or T3SS-deficient Y. pseudotuberculosis but diminished in the presence of a MAPK/ERK inhibitor. Mutants expressing catalytically inactive YopJ induce similar levels of PGE2 as heat-killed or ΔyopB Y. pseudotuberculosis, reversed by YopJ complementation. Shotgun proteomics discovered host pathways regulated in a YopJ-mediated manner, including pathways regulating PGE2 synthesis and oxidative phosphorylation. Consequently, this study identified that YopJ-mediated inhibition of MAPK signal transduction serves as a mechanism targeting PGE2, an alternative means of inflammasome inhibition by Yersinia. Finally, we showed that EP4 signaling supports macrophage function in clearing intracellular bacteria. In summary, our unique contribution was to determine a bacterial virulence factor that targets COX-2 transcription, thereby enhancing the intracellular survival of yersiniae. Future studies should investigate whether PGE2 or its stable synthetic derivatives could serve as a potential therapeutic molecule to improve the outcomes of specific bacterial infections. Since other pathogens encode YopJ homologs, this mechanism is expected to be present in other infections. IMPORTANCE PGE2 is a critical immunomodulatory lipid, but its role in bacterial infection and pathogen clearance is poorly understood. We previously demonstrated that PGE2 leads to macrophage polarization toward the M1 phenotype and stimulates inflammasome activation in infected macrophages. Finally, we also discovered that PGE2 improved the clearance of Y. enterocolitica. The fact that Y. enterocolitica hampers PGE2 secretion in a type 3 secretion system (T3SS)-dependent manner and because PGE2 appears to assist macrophage in the clearance of this bacterium indicates that targeting of the eicosanoid pathway by Yersinia might be an adaption used to counteract host defenses. Our study identified a mechanism used by Yersinia that obstructs PGE2 biosynthesis in human macrophages. We showed that Y. pseudotuberculosis interferes with PGE2 biosynthesis by using one of its T3SS effectors, YopJ. Specifically, YopJ targets the host COX-2 enzyme responsible for PGE2 biosynthesis, which happens in a MAPK/ER-dependent manner. Moreover, in a shotgun proteomics study, we also discovered other pathways that catalytically active YopJ targets in the infected macrophages. YopJ was revealed to play a role in limiting host LPS responses, including repression of EGR1 and JUN proteins, which control transcriptional activation of proinflammatory cytokine production such as interleukin-1β. Since YopJ has homologs in other bacterial species, there are likely other pathogens that target and inhibit PGE2 biosynthesis. In summary, our study's unique contribution was to determine a bacterial virulence factor that targets COX-2 transcription. Future studies should investigate whether PGE2 or its stable synthetic derivatives could serve as a potential therapeutic target.

Impact of Toll-Like Receptor-Specific Agonists on the Host Immune Response to the Yersinia pestis Plague rF1V Vaccine

Relatively recent advances in plague vaccinology have produced the recombinant fusion protein F1-V plague vaccine. This vaccine has been shown to readily protect mice from both bubonic and pneumonic plague. The protection afforded by this vaccine is solely based upon the immune response elicited by the F1 or V epitopes expressed on the F1-V fusion protein. Accordingly, questions remain surrounding its efficacy against infection with non-encapsulated (F1-negative) strains. In an attempt to further optimize the F1-V elicited immune response and address efficacy concerns, we examined the inclusion of multiple toll-like receptor agonists into vaccine regimens. We examined the resulting immune responses and also any protection afforded to mice that were exposed to aerosolized Yersinia pestis. Our data demonstrate that it is possible to further augment the F1-V vaccine strategy in order to optimize and augment vaccine efficacy.

Antimicrobial Treatment and Prophylaxis of Plague: Recommendations for Naturally Acquired Infections and Bioterrorism Response

This report provides CDC recommendations to U.S. health care providers regarding treatment, pre-exposure prophylaxis, and postexposure prophylaxis of plague. Yersinia pestis, the bacterium that causes plague, leads to naturally occurring disease in the United States and other regions worldwide and is recognized as a potential bioterrorism weapon. A bioweapon attack with Y. pestis could potentially infect thousands, requiring rapid and informed decision making by clinicians and public health agencies. The U.S. government stockpiles a variety of medical countermeasures to mitigate the effects of a bioterrorism attack (e.g., antimicrobials, antitoxins, and vaccines) for which the 21st Century Cures Act mandates the development of evidence-based guidelines on appropriate use. Guidelines for treatment and postexposure prophylaxis of plague were published in 2000 by a nongovernmental work group; since then, new human clinical data, animal study data, and U.S. Food and Drug Administration approvals of additional countermeasures have become available. To develop a comprehensive set of updated guidelines, CDC conducted a series of systematic literature reviews on human treatment of plague and other relevant topics to collect a broad evidence base for the recommendations in this report. Evidence from CDC reviews and additional sources were presented to subject matter experts during a series of forums. CDC considered individual expert input while developing these guidelines, which provide recommended best practices for treatment and prophylaxis of human plague for both naturally occurring disease and following a bioterrorism attack. The guidelines do not include information on diagnostic testing, triage decisions, or logistics involved in dispensing medical countermeasures. Clinicians and public health officials can use these guidelines to prepare their organizations, hospitals, and communities to respond to a plague mass-casualty event and as a guide for treating patients affected by plague.

Regional Rodent-Borne Infectious Diseases in North America: What Wilderness Medicine Providers Need to Know

Rodents can transmit infectious diseases directly to humans and other animals via bites and exposure to infectious salivary aerosols and excreta. Arthropods infected while blood-feeding on rodents can also transmit rodent-borne pathogens indirectly to humans and animals. Environmental events, such as wet winters, cooler summers, heavy rains, and flooding, have precipitated regional rodent-borne infectious disease outbreaks; these outbreaks are now increasing with climate change. The objectives of this review are to inform wilderness medicine providers about the environmental conditions that can precipitate rodent-borne infectious disease outbreaks; to describe the regional geographic distributions of rodent-borne infectious diseases in North America; and to recommend prophylactic treatments and effective prevention and control strategies for rodent-borne infectious diseases. To meet these objectives, Internet search engines were queried with keywords to identify scientific articles on outbreaks of the most common regional rodent-borne infectious diseases in North America. Wilderness medicine providers should maintain high levels of suspicion for regional rodent-borne diseases in patients who develop febrile illnesses after exposure to contaminated freshwater after heavy rains or floods and after swimming, rafting, or paddling in endemic areas. Public health education strategies should encourage limiting human contact with rodents; avoiding contact with or safely disposing of rodent excreta; avoiding contact with contaminated floodwaters, especially contact with open wounds; securely containing outdoor food stores; and modifying wilderness cabins and campsites to deter rodent colonization.

Chronicle down memory lane: India's sixty years of plague experience

BACKGROUND

This perspective documents the historical aspects of outbreaks of plague of last six decades, establishment of plague surveillance network in India with detailed insights about its activities and recent developments requiring focus on plague surveillance. Human plague was reported in Mulbagal area of Karnataka in 1966-67 only to re-emerge in the country in 1994 in Beed district (Maharashtra) and subsequently in Surat (Gujarat). Later Plague outbreak has been reported in the year 2002 with index case from Village Hatkoti, Shimla District in Himachal Pradesh. The last outbreak reported from India was in 2004 from Village Dangaud, Uttarkashi District in Uttarakhand followed by a period of quiescent since last 17 years.

OBJECTIVES

During the last few decades, at least three geographical areas experienced outbreaks of plague after silent period of 28 years. We recapitulate the response mechanism for containing outbreaks during the last three outbreaks of plague held in Maharashtra & Gujarat (1994), Himachal Pradesh (2002) and Uttarakhand (2004). We also document the Plague surveillance network of India and its activities which is a comprehensive surveillance system comprising of rodent, flea, canine and human surveillance whose foundation was started in 1964. The recent developments of last decade in terms of revised Human plague surveillance case definitions, Plague surveillance sites, vector control, novel diagnostics and vaccines in our country are also mentioned.

CONCLUSION

The thrust areas in control of plague outbreak are early detection and isolation of cases, timely effective antibiotic treatment, chemoprophylaxis to contacts, strengthening of surveillance system and massive IEC campaign in infected areas. Yersinia pestis (causative agent of Plague) also being an important bioterrorism agent, clinicians need to pay special attention to diagnose and microbiologists must be provided skilled training for laboratory confirmation to this pestilential disease for effective and timely management.

Secretory System Components as Potential Prophylactic Targets for Bacterial Pathogens

Bacterial secretory systems are essential for virulence in human pathogens. The systems have become a target of alternative antibacterial strategies based on small molecules and antibodies. Strategies to use components of the systems to design prophylactics have been less publicized despite vaccines being the preferred solution to dealing with bacterial infections. In the current review, strategies to design vaccines against selected pathogens are presented and connected to the biology of the system. The examples are given for Y. pestis, S. enterica, B. anthracis, S. flexneri, and other human pathogens, and discussed in terms of effectiveness and long-term protection.

Plague vaccines: new developments in an ongoing search

As the reality of pandemic threats challenges humanity, exemplified during the ongoing SARS-CoV-2 infections, the development of vaccines targeting these etiological agents of disease has become increasingly critical. Of paramount concern are novel and reemerging pathogens that could trigger such events, including the plague bacterium Yersinia pestis. Y. pestis is responsible for more human deaths than any other known pathogen and exists globally in endemic regions of the world, including the four corners region and Northern California in the USA. Recent cases have been scattered throughout the world, including China and the USA, with serious outbreaks in Madagascar during 2008, 2013-2014, and, most recently, 2017-2018. This review will focus on recent advances in plague vaccine development, a seemingly necessary endeavor, as there is no Food and Drug Administration-licensed vaccine available for human distribution in western nations, and that antibiotic-resistant strains are recovered clinically or intentionally developed. Progress and recent development involving subunit, live-attenuated, and nucleic acid-based plague vaccine candidates will be discussed in this review. KEY POINTS: • Plague vaccine development remains elusive yet critical. • DNA, animal, and live-attenuated vaccine candidates gain traction.

Finafloxacin Is an Effective Treatment for Inhalational Tularemia and Plague in Mouse Models of Infection

Infection with aerosolized Francisella tularensis or Yersinia pestis can lead to lethal disease in humans if treatment is not initiated promptly. Finafloxacin is a novel fluoroquinolone which has demonstrated broad-spectrum activity against a range of bacterial species in vitro, in vivo, and in humans, activity which is superior in acidic, infection-relevant conditions. Human-equivalent doses of finafloxacin or ciprofloxacin were delivered at 24 h (representing prophylaxis) or at 72 or 38 h (representing treatment) postchallenge with F. tularensis or Y. pestis, respectively, in BALB/c mouse models. In addition, a short course of therapy (3 days) was compared to a longer course (7 days). Both therapies provided a high level of protection against both infections when administered at 24 h postchallenge, irrespective of the length of the dosing regimen; however, differences were observed when therapy was delayed. A benefit was demonstrated with finafloxacin compared to ciprofloxacin in both models when therapy was delivered later in the infection. These studies suggest that finafloxacin is an effective alternative therapeutic for the prophylaxis and treatment of inhalational infections with F. tularensis or Y. pestis.

Two fatal cases of plague after consumption of raw marmot organs

Marmots are an important reservoir of Yersinia pestis and a source of human plague in Mongolia. We present two fatal cases of plague after consumption of raw marmot organs and discuss the distribution of natural foci of Y. pestis in Mongolia.

Lack of Molecular Mimicry between Nonhuman Primates and Infectious Pathogens: The Possible Genetic Bases

Recently, it was found that proteomes from poliovirus, measles virus, dengue virus, and severe acute respiratory syndrome-related Coronavirus 2 (SARS-CoV-2) have high molecular mimicry at the heptapeptide level with the human proteome, while heptapeptide commonality is minimal or absent with proteomes from nonhuman primates, that is, gorilla, chimpanzee, and rhesus macaque. To acquire more data on the issue, analyses here have been expanded to Ebola virus, Francisella tularensis , human immunodeficiency virus-1 (HIV-1), Toxoplasma gondii , Variola virus, and Yersinia pestis . Results confirm that heptapeptide overlap is high between pathogens and Homo sapiens , but not between pathogens and primates. Data are discussed in light of the possible genetic bases that differently model primate phenomes, thus possibly underlying the zero/low level of molecular mimicry between infectious agents and primates. Notably, this study might help address preclinical vaccine tests that currently utilize primates as animal models, since autoimmune cross-reactions and the consequent adverse events cannot occur in absentia of shared sequences.

COVID-19 Vaccines: Preparing for Vaccination in the Context of Clinical Oncology Care

BACKGROUND

In the environment of an infectious pandemic, vaccines are a primary public health strategy to prevent the spread of disease. With the COVID-19 pandemic, there is heightened interest in safe and effective vaccines and their use in the context of clinical oncology practice.

OBJECTIVES

This article provides foundational information about vaccines in general and vaccines developed to protect against the SARS-CoV-2 virus in the United States, as well as clinical nurse strategies to apply vaccines in clinical oncology practice.

METHODS

The article is based on a review of public health literature and reputable websites about vaccines and their development in clinical care.

FINDINGS

This foundational information about vaccines reviews their history and development, as well as the development of COVID-19 vaccines specifically, and discusses COVID-19 vaccines as part of clinical oncology care. Supporting best practices in clinical oncology care, nurses can provide factual, evidence-based information about vaccine safety, effectiveness, and safe administration.

Single-dose intranasal subunit vaccine rapidly clears secondary sepsis in a high-dose pneumonic plague infection

Yersinia pestis, the causative agent of plague, has killed millions throughout human history. Though public health initiatives have reduced the number of plague cases, it remains endemic in many areas of the world. It also remains a significant threat for use as a biological weapon. Naturally occurring multi-drug antibiotic resistance has been observed in Y. pestis, and resistant strains have been engineered for use as a biological weapon. Vaccines represent our best means of protection against the threat of antibiotic resistant plague. We have developed a vaccine consisting of two Y. pestis virulence factors, LcrV (V) and F1, conjugated to Tobacco Mosaic Virus (TMV), a safe, non-replicating plant virus that can be administered mucosally, providing complete protection against pneumonic plague, the deadliest form of the disease and the one most likely to be seen in a biological attack. A single intranasal (i.n.) dose of TMV-F1 + TMV-V (TMV-F1/V) protected 88% of mice against lethal challenge with 100 LD₅₀ of Y. pestis CO92pgm-, while immunization with rF1 + rV without TMV was not protective. Serum and tissues were collected at various timepoints after challenge to assess bacterial clearance, histopathology, cytokine production, and antibody production. Overall, TMV-F1/V immunized mice showed a significant reduction in histopathology, bacterial burden, and inflammatory cytokine production following challenge compared to rF1 + rV vaccinated and unvaccinated mice. Pneumonic challenge resulted in systemic dissemination of the bacteria in all groups, but only TMV-F1/V immunized mice rapidly cleared bacteria from the spleen and liver. There was a direct correlation between pre-challenge serum F1 titers and recovery in all immunized mice, strongly suggesting a role for antibody in the neutralization and/or opsonization of Y. pestis in this model. Mucosal administration of a single dose of a Y. pestis TMV-based subunit vaccine, without any additional adjuvant, can effectively protect mice from lethal infection.

A new generation needle- and adjuvant-free trivalent plague vaccine utilizing adenovirus-5 nanoparticle platform

A plague vaccine with a fusion cassette of YscF, F1, and LcrV encoding genes in an adenovirus-5 vector (rAd5-YFV) is evaluated for efficacy and immune responses in mice. Two doses of the vaccine provides 100% protection when administered intranasally against challenge with Yersinia pestis CO92 or its isogenic F1 mutant in short- or long- term immunization in pneumonic/bubonic plague models. The corresponding protection rates drop in rAd5-LcrV monovalent vaccinated mice in plague models. The rAd5-YFV vaccine induces superior humoral, mucosal and cell-mediated immunity, with clearance of the pathogen. Immunization of mice with rAd5-YFV followed by CO92 infection dampens proinflammatory cytokines and neutrophil chemoattractant production, while increasing Th1- and Th2-cytokine responses as well as macrophage/monocyte chemo-attractants when compared to the challenge control animals. This is a first study showing complete protection of mice from pneumonic/bubonic plague with a viral vector-based vaccine without the use of needles and the adjuvant.

Pandemics Throughout History

The emergence and spread of infectious diseases with pandemic potential occurred regularly throughout history. Major pandemics and epidemics such as plague, cholera, flu, severe acute respiratory syndrome coronavirus (SARS-CoV) and Middle East respiratory syndrome coronavirus (MERS-CoV) have already afflicted humanity. The world is now facing the new coronavirus disease 2019 (COVID-19) pandemic. Many infectious diseases leading to pandemics are caused by zoonotic pathogens that were transmitted to humans due to increased contacts with animals through breeding, hunting and global trade activities. The understanding of the mechanisms of transmission of pathogens to humans allowed the establishment of methods to prevent and control infections. During centuries, implementation of public health measures such as isolation, quarantine and border control helped to contain the spread of infectious diseases and maintain the structure of the society. In the absence of pharmaceutical interventions, these containment methods have still been used nowadays to control COVID-19 pandemic. Global surveillance programs of water-borne pathogens, vector-borne diseases and zoonotic spillovers at the animal-human interface are of prime importance to rapidly detect the emergence of infectious threats. Novel technologies for rapid diagnostic testing, contact tracing, drug repurposing, biomarkers of disease severity as well as new platforms for the development and production of vaccines are needed for an effective response in case of pandemics.

Potential human immunotherapeutics for plague

Two monoclonal antibodies directed to the V antigen of Yersinia pestis have been tested for protective efficacy in a murine model of bubonic plague. Mice were infected with a current clinical isolate from Madagascar, designated Y. pestis 10-21/S. Mab7.3, delivered to mice intra-periteoneally at either 24 h prior to, or 24 h post-infection, was fully protective, building on many studies which have demonstrated the protective efficacy of this Mab against a number of different clinical isolates of Y. pestis. Mab 29.3, delivered intra-peritoneally at either -24 h or +24 h, protected 4/5 mice in either condition; this has demonstrated the protective efficacy of this Mab in vivo for the first time. These results add to the cumulative data about Mab7.3, which is currently being humanized and highlight its potential as a human immunotherapeutic for plague, which is an enduring endemic disease in Madagascar and other regions of Africa, Asia, and South America.

Yersinia Outer Membrane Vesicles as Potential Vaccine Candidates in Protecting against Plague

Despite the relatively low incidence of plague, its etiological agent, Yersinia pestis, is an exceptional epidemic danger due to the high infectivity and mortality of this infectious disease. Reports on the isolation of drug-resistant Y. pestis strains indicate the advisability of using asymmetric responses, such as phage therapy and vaccine prophylaxis in the fight against this problem. The current relatively effective live plague vaccine is not approved for use in most countries because of its ability to cause heavy local and system reactions and even a generalized infectious process in people with a repressed immune status or metabolic disorders, as well as lethal infection in some species of nonhuman primates. Therefore, developing alternative vaccines is of high priority and importance. However, until now, work on the development of plague vaccines has mainly focused on screening for the potential immunogens. Several investigators have identified the protective potency of bacterial outer membrane vesicles (OMVs) as a promising basis for bacterial vaccine candidates. This review is aimed at presenting these candidates of plague vaccine and the results of their analysis in animal models.

Factors influencing the re-emergence of plague in Madagascar

Plague is an infectious disease found worldwide and has been responsible for pandemics throughout history. Yersinia pestis, the causative bacterium, survives in rodent hosts with flea vectors that also transmit it to humans. It has been endemic in Madagascar for a century but the 1990s saw major outbreaks and in 2006 the WHO described the plague as re-emerging in Madagascar and the world. This review highlights the variety of factors leading to plague re-emergence in Madagascar, including climate events, insecticide resistance, and host and human behaviour. It also addresses areas of concern for future epidemics and ways to mitigate these. Pinpointing and addressing current and future drivers of plague re-emergence in Madagascar will be essential to controlling future outbreaks both in Madagascar and worldwide.

Shaping Modern Vaccines: Adjuvant Systems Using MicroCrystalline Tyrosine (MCT®)

The concept of adjuvants or adjuvant systems, used in vaccines, exploit evolutionary relationships associated with how the immune system may initially respond to a foreign antigen or pathogen, thus mimicking natural exposure. This is particularly relevant during the non-specific innate stage of the immune response; as such, the quality of this response may dictate specific adaptive responses and conferred memory/protection to that specific antigen or pathogen. Therefore, adjuvants may optimise this response in the most appropriate way for a specific disease. The most commonly used traditional adjuvants are aluminium salts; however, a biodegradable adjuvant, MCT®, was developed for application in the niche area of allergy immunotherapy (AIT), also in combination with a TLR-4 adjuvant-Monophosphoryl Lipid A (MPL®)-producing the first adjuvant system approach for AIT in the clinic. In the last decade, the use and effectiveness of MCT® across a variety of disease models in the preclinical setting highlight it as a promising platform for adjuvant systems, to help overcome the challenges of modern vaccines. A consequence of bringing together, for the first time, a unified view of MCT® mode-of-action from multiple experiments and adjuvant systems will help facilitate future rational design of vaccines while shaping their success.

Vaccine Potential of a Recombinant Bivalent Fusion Protein LcrV-HSP70 Against Plague and Yersiniosis

To counteract the deadly pathogens, i.e., Y. pestis, Y. enetrocolitica, and Y. pseudotuberculosis, we prepared a recombinant DNA construct lcrV-hsp70 encoding the bivalent fusion protein LcrV-HSP70. The lcrV gene of Y. pestis and hsp70 domain II DNA fragment of M. tuberculosis were amplified by PCR. The lcrV amplicon was first ligated in the pET vector using NcoI and BamHI restriction sites. Just downstream to the lcrV gene, the hsp70 domain II was ligated using BamHI and Hind III restriction sites. The in-frame and the orientation of cloned lcrV-hsp70 were checked by restriction analysis and nucleotide sequencing. The recombinant bivalent fusion protein LcrV-HSP70 was expressed in E. coli and purified by affinity chromatography. The vaccine potential of LcrV-HSP70 fusion protein was evaluated in formulation with alum. BALB/c mice were vaccinated, and the humoral and cellular immune responses were studied. The fusion protein LcrV-HSP70 induced a strong and significant humoral immune response in comparison to control animals. We also observed a significant difference in the expression levels of IFN-γ and TNF-α in LcrV–HSP70-immunized mice in comparison to control, HSP70, and LcrV groups. To test the protective efficacy of the LcrV–HSP70 fusion protein against plague and Yersiniosis, the vaccinated mice were challenged with Y. pestis, Y. enterocolitica, and Y. pseudotuberculosis separately. The bivalent fusion protein LcrV–HSP70 imparted 100% protection against the plague. In the case of Yersiniosis, on day 2 post challenge, there was a significant reduction in the number of CFU of Y. enterocolitica and Y. pseudotuberculosis in the blood (CFU/ml) and the spleen (CFU/g) of vaccinated animals in comparison to the LcrV, HSP70, and control group animals.

Current Challenges in Vaccinology

The development of vaccines, which prime the immune system to respond to future infections, has led to global declines in morbidity and mortality from dreadful infectious communicable diseases. However, many pathogens of public health importance are highly complex and/or rapidly evolving, posing unique challenges to vaccine development. Several of these challenges include an incomplete understanding of how immunity develops, host and pathogen genetic variability, and an increased societal skepticism regarding vaccine safety. In particular, new high-dimensional omics technologies, aided by bioinformatics, are driving new vaccine development (vaccinomics). Informed by recent insights into pathogen biology, host genetic diversity, and immunology, the increasing use of genomic approaches is leading to new models and understanding of host immune system responses that may provide solutions in the rapid development of novel vaccine candidates.

Climate drivers of plague epidemiology in British India, 1898-1949

Plague, caused by Yersinia pestis infection, continues to threaten low- and middle-income countries throughout the world. The complex interactions between rodents and fleas with their respective environments challenge our understanding of human plague epidemiology. Historical long-term datasets of reported plague cases offer a unique opportunity to elucidate the effects of climate on plague outbreaks in detail. Here, we analyse monthly plague deaths and climate data from 25 provinces in British India from 1898 to 1949 to generate insights into the influence of temperature, rainfall and humidity on the occurrence, severity and timing of plague outbreaks. We find that moderate relative humidity levels of between 60% and 80% were strongly associated with outbreaks. Using wavelet analysis, we determine that the nationwide spread of plague was driven by changes in humidity, where, on average, a one-month delay in the onset of rising humidity translated into a one-month delay in the timing of plague outbreaks. This work can inform modern spatio-temporal predictive models for the disease and aid in the development of early-warning strategies for the deployment of prophylactic treatments and other control measures.