Controlled Human Infection With Bordetella pertussis Induces Asymptomatic, Immunizing Colonization.

BACKGROUND: Bordetella pertussis is among the leading causes of vaccine-preventable deaths and morbidity globally. Human asymptomatic carriage as a reservoir for community transmission of infections might be a target of future vaccine strategies, but has not been demonstrated. Our objective was to demonstrate that asymptomatic nasopharyngeal carriage of Bordetella pertussis is inducible in humans and to define the microbiological and immunological features of presymptomatic infection. METHODS: Healthy subjects aged 18-45 years with an antipertussis toxin immunoglobin G (IgG) concentration of <20 international units/ml were inoculated intranasally with nonattenuated, wild-type Bordetella pertussis strain B1917. Safety, colonization, and shedding were monitored over 17 days in an inpatient facility. Colonization was assessed by culture and quantitative polymerase chain reaction. Azithromycin was administered from Day 14. The inoculum dose was escalated, aiming to colonize at least 70% of participants. Immunological responses were measured. RESULTS: There were 34 participants challenged, in groups of 4 or 5. The dose was gradually escalated from 103 colony-forming units (0% colonized) to 105 colony-forming units (80% colonized). Minor symptoms were reported in a minority of participants. Azithromycin eradicated colonization in 48 hours in 88% of colonized individuals. Antipertussis toxin IgG seroconversion occurred in 9 out of 19 colonized participants and in none of the participants who were not colonized. Nasal wash was a more sensitive method to detect colonization than pernasal swabs. No shedding of Bordetella pertussis was detected in systematically collected environmental samples. CONCLUSIONS: Bordetella pertussis colonization can be deliberately induced and leads to a systemic immune response without causing pertussis symptoms. CLINICAL TRIALS REGISTRATION: NCT03751514.

The antimicrobial resistance monitoring and research (ARMoR) program: the US Department of Defense response to escalating antimicrobial resistance.

Responding to escalating antimicrobial resistance (AMR), the US Department of Defense implemented an enterprise-wide collaboration, the Antimicrobial Resistance Monitoring and Research Program, to aid in infection prevention and control. It consists of a network of epidemiologists, bioinformaticists, microbiology researchers, policy makers, hospital-based infection preventionists, and healthcare providers who collaborate to collect relevant AMR data, conduct centralized molecular characterization, and use AMR characterization feedback to implement appropriate infection prevention and control measures and influence policy. A particularly concerning type of AMR, carbapenem-resistant Enterobacteriaceae, significantly declined after the program was launched. Similarly, there have been no further reports or outbreaks of another concerning type of AMR, colistin resistance in Acinetobacter, in the Department of Defense since the program was initiated. However, bacteria containing AMR-encoding genes are increasing. To update program stakeholders and other healthcare systems facing such challenges, we describe the processes and impact of the program.

A CD4(+) T-cell immune response to a conserved epitope in the circumsporozoite protein correlates with protection from natural Plasmodium falciparum infection and disease.

Many human T-cell responses specific for epitopes in Plasmodium falciparum have been described, but none has yet been shown to be predictive of protection against natural malaria infection. Here we report a peptide-specific T-cell assay that is strongly associated with protection of humans in The Gambia, West Africa, from both malaria infection and disease. The assay detects interferon-gamma-secreting CD4(+) T cells specific for a conserved sequence from the circumsporozoite protein, which binds to many human leukocyte antigen (HLA)-DR types. The correlation was observed using a cultured, rather than an ex vivo, ELISPOT assay that measures central memory-'type T cells rather than activated effector T cells. These findings provide direct evidence for a protective role for CD4(+) T cells in humans, and a precise target for the design of improved vaccines against P. falciparum.

Enhanced T-cell immunogenicity of plasmid DNA vaccines boosted by recombinant modified vaccinia virus Ankara in humans.

In animals, effective immune responses against malignancies and against several infectious pathogens, including malaria, are mediated by T cells. Here we show that a heterologous prime-boost vaccination regime of DNA either intramuscularly or epidermally, followed by intradermal recombinant modified vaccinia virus Ankara (MVA), induces high frequencies of interferon (IFN)-gamma-secreting, antigen-specific T-cell responses in humans to a pre-erythrocytic malaria antigen, thrombospondin-related adhesion protein (TRAP). These responses are five- to tenfold higher than the T-cell responses induced by the DNA vaccine or recombinant MVA vaccine alone, and produce partial protection manifest as delayed parasitemia after sporozoite challenge with a different strain of Plasmodium falciparum. Such heterologous prime-boost immunization approaches may provide a basis for preventative and therapeutic vaccination in humans.

Executive summary: Guidelines for the prevention of infections associated with combat-related injuries: 2011 update: endorsed by the Infectious Diseases Society of America and the Surgical Infection Society.

Despite advances in resuscitation and surgical management of combat wounds, infection remains a concerning and potentially preventable complication of combat-related injuries. Interventions currently used to prevent these infections have not been either clearly defined or subjected to rigorous clinical trials. Current infection prevention measures and wound management practices are derived from retrospective review of wartime experiences, from civilian trauma data, and from in vitro and animal data. This update to the guidelines published in 2008 incorporates evidence that has become available since 2007. These guidelines focus on care provided within hours to days of injury, chiefly within the combat zone, to those combat-injured patients with open wounds or burns. New in this update are a consolidation of antimicrobial agent recommendations to a backbone of high-dose cefazolin with or without metronidazole for most postinjury indications and recommendations for redosing of antimicrobial agents, for use of negative pressure wound therapy, and for oxygen supplementation in flight.

Guidelines for the prevention of infections associated with combat-related injuries: 2011 update: endorsed by the Infectious Diseases Society of America and the Surgical Infection Society.

Despite advances in resuscitation and surgical management of combat wounds, infection remains a concerning and potentially preventable complication of combat-related injuries. Interventions currently used to prevent these infections have not been either clearly defined or subjected to rigorous clinical trials. Current infection prevention measures and wound management practices are derived from retrospective review of wartime experiences, from civilian trauma data, and from in vitro and animal data. This update to the guidelines published in 2008 incorporates evidence that has become available since 2007. These guidelines focus on care provided within hours to days of injury, chiefly within the combat zone, to those combat-injured patients with open wounds or burns. New in this update are a consolidation of antimicrobial agent recommendations to a backbone of high-dose cefazolin with or without metronidazole for most postinjury indications, and recommendations for redosing of antimicrobial agents, for use of negative pressure wound therapy, and for oxygen supplementation in flight.

Expression of genes associated with immunoproteasome processing of major histocompatibility complex peptides is indicative of protection with adjuvanted RTS,S malaria vaccine.

BACKGROUND: Patterns of expressed genes in the peripheral blood mononuclear cells of persons who were receiving RTS,S/AS01 or RTS,S/AS02 malaria vaccine and were undergoing experimental challenge with mosquito-borne falciparum malaria were examined to identify markers associated with protection. METHODS: Thirty-nine vaccine recipients were assessed at study entry; on the day of the third vaccination; at 24 h, 72 h, and 2 weeks after vaccination; and on day 5 after challenge. Of 39 vaccine recipients, 13 were protected and 26 were not. Eleven vaccine recipients exhibited delayed onset of parasitemia. All infectivity control subjects developed parasitemia. Prediction analysis of microarrays identified genes corresponding with protection. Gene set enrichment analysis identified sets of genes associated with protection after the third vaccination and before challenge. RESULTS: After the third vaccination and before challenge, differential expression of genes in the immunoproteasome pathway distinguished protected and nonprotected persons. At 5 days after challenge, differential expression of genes associated with programmed cell death distinguished between subjects protected and not protected from malaria blood-stage infection. CONCLUSIONS: The up-regulation of genes associated with the efficient processing of major histocompatibility complex peptides suggests a potential role of the vaccine in conferring major histocompatibility complex class 1-mediated protection and may represent a useful surrogate marker of vaccine efficacy without the need for challenge.

The promise of mRNA vaccines: a biotech and industrial perspective.

mRNA technologies have the potential to transform areas of medicine, including the prophylaxis of infectious diseases. The advantages for vaccines range from the acceleration of immunogen discovery to rapid response and multiple disease target manufacturing. A greater understanding of quality attributes that dictate translation efficiency, as well as a comprehensive appreciation of the importance of mRNA delivery, are influencing a new era of investment in development activities. The application of translational sciences and growing early-phase clinical experience continue to inform candidate vaccine selection. Here we review the state of the art for the prevention of infectious diseases by using mRNA and pertinent topics to the biotechnology and pharmaceutical industries.

Summit proceedings: Biomedical countermeasure development for emerging vector-borne viral diseases.

Emerging and re-emerging infectious diseases are an expanding global threat to public health, security, and economies. Increasing populations, urbanization, deforestation, climate change, anti-vaccination movements, war, and international travel are some of the contributing factors to this trend. The recent Ebola, MERS-CoV, and Zika outbreaks demonstrated we are insufficiently prepared to respond with proven safe and effective countermeasures (i.e., vaccines and therapeutics). The State University of New York Upstate Medical University and the Trudeau Institute convened a summit of key opinion and thought leaders in the life sciences and biomedical research and development enterprises to explore global biopreparedness challenges, take an inventory of existing capabilities and capacities related to preparation and response, assess current "gaps," and prospect what could be done to improve our position. Herein we describe the summit proceedings, "Translational Immunology Supporting Biomedical Countermeasure Development for Emerging Vector-borne Viral Diseases," held October 2-3, 2018, at the Trudeau Institute in Saranac Lake, NY.

Cholesterol-conjugated stapled peptides inhibit Ebola and Marburg viruses in vitro and in vivo.

Filoviridae currently includes five official and one proposed genera. Genus Ebolavirus includes five established and one proposed ebolavirus species for Bombali virus (BOMV), Bundibugyo virus (BDBV), Ebola virus (EBOV), Reston virus (RESTV), Sudan virus (SUDV) and Taï Forest virus (TAFV), and genus Marburgvirus includes a single species for Marburg virus (MARV) and Ravn virus (RAVV). Ebola virus (EBOV) has emerged as a significant public health concern since the 2013-2016 Ebola Virus Disease outbreak in Western Africa. Currently, there are no therapeutics approved and the need for Ebola-specific therapeutics remains a gap. In search for anti-Ebola therapies we tested the idea of using inhibitory properties of peptides corresponding to the C-terminal heptad-repeat (HR2) domains of class I fusion proteins against EBOV infection. The fusion protein GP2 of EBOV belongs to class I, suggesting that a similar strategy to HIV may be applied to inhibit EBOV infection. The serum half-life of peptides was expanded by cholesterol conjugation to allow daily dosing. The peptides were further constrained to stabilize a helical structure to increase the potency of inhibition. The EC50s of lead peptides were in low micromolar range, as determined by a high-content imaging test of EBOV-infected cells. Lead peptides were tested in an EBOV lethal mouse model and efficacy of the peptides were determined following twice-daily administration of peptides for 9 days. The most potent peptide was able to protect mice from lethal challenge of mouse-adapted Ebola virus. These data show that engineered peptides coupled with cholesterol can inhibit viral production, protect mice against lethal EBOV infection, and may be used to build novel therapeutics against EBOV.

Characterization of potential biomarkers of reactogenicity of licensed antiviral vaccines: randomized controlled clinical trials conducted by the BIOVACSAFE consortium.

Biomarkers predictive of inflammatory events post-vaccination could accelerate vaccine development. Within the BIOVACSAFE framework, we conducted three identically designed, placebo-controlled inpatient/outpatient clinical studies (NCT01765413/NCT01771354/NCT01771367). Six antiviral vaccination strategies were evaluated to generate training data-sets of pre-/post-vaccination vital signs, blood changes and whole-blood gene transcripts, and to identify putative biomarkers of early inflammation/reactogenicity that could guide the design of subsequent focused confirmatory studies. Healthy adults (N = 123; 20-21/group) received one immunization at Day (D)0. Alum-adjuvanted hepatitis B vaccine elicited vital signs and inflammatory (CRP/innate cells) responses that were similar between primed/naive vaccinees, and low-level gene responses. MF59-adjuvanted trivalent influenza vaccine (ATIV) induced distinct physiological (temperature/heart rate/reactogenicity) response-patterns not seen with non-adjuvanted TIV or with the other vaccines. ATIV also elicited robust early (D1) activation of IFN-related genes (associated with serum IP-10 levels) and innate-cell-related genes, and changes in monocyte/neutrophil/lymphocyte counts, while TIV elicited similar but lower responses. Due to viral replication kinetics, innate gene activation by live yellow-fever or varicella-zoster virus (YFV/VZV) vaccines was more suspended, with early IFN-associated responses in naïve YFV-vaccine recipients but not in primed VZV-vaccine recipients. Inflammatory responses (physiological/serum markers, innate-signaling transcripts) are therefore a function of the vaccine type/composition and presence/absence of immune memory. The data reported here have guided the design of confirmatory Phase IV trials using ATIV to provide tools to identify inflammatory or reactogenicity biomarkers.

Investigating Bordetella pertussis colonisation and immunity: protocol for an inpatient controlled human infection model.

INTRODUCTION: We summarise an ethically approved protocol for the development of an experimental human challenge colonisation model. Globally Bordetella pertussis is one of the leading causes of vaccine-preventable death. Many countries have replaced whole cell vaccines with acellular vaccines over the last 20 years during which pertussis appears to be resurgent in a number of countries in the developed world that boast high immunisation coverage. The acellular vaccine provides relatively short-lived immunity and, in contrast to whole cell vaccines, may be less effective against colonisation and subsequent transmission. To improve vaccine strategies, a greater understanding of human B. pertussis colonisation is required. This article summarises a protocol and does not contain any results. METHODS AND ANALYSIS: A controlled human colonisation model will be developed over two phases. In phase A, a low dose of the inoculum will be given intranasally to healthy participants. This dose will be escalated or de-escalated until colonisation is achieved in approximately 70% (95% CI 47% to 93%) of the exposed volunteers without causing disease. The colonisation period, shedding and exploratory immunology will be assessed during a 17-day inpatient stay and follow-up over 1 year. The dose of inoculum that achieves 70% colonisation will then be confirmed in phase B, comparing healthy participants exposed to B. pertussis with a control group receiving a sham inoculum. ETHICS AND DISSEMINATION: This study has been approved by the ethical committee reference: 17/SC/0006, 24 February 2017. Findings will be published in peer-reviewed open access journals as soon as possible.

Predicting RTS,S Vaccine-Mediated Protection from Transcriptomes in a Malaria-Challenge Clinical Trial.

The RTS,S candidate malaria vaccine can protect against controlled human malaria infection (CHMI), but how protection is achieved remains unclear. Here, we have analyzed longitudinal peripheral blood transcriptome and immunogenicity data from a clinical efficacy trial in which healthy adults received three RTS,S doses 4 weeks apart followed by CHMI 2 weeks later. Multiway partial least squares discriminant analysis (N-PLS-DA) of transcriptome data identified 110 genes that could be used in predictive models of protection. Among the 110 genes, 42 had known immune-related functions, including 29 that were related to the NF-κB-signaling pathway and 14 to the IFN-γ-signaling pathway. Post-dose 3 serum IFN-γ concentrations were also correlated with protection; and N-PLS-DA of IFN-γ-signaling pathway transcriptome data selected almost all (44/45) of the representative genes for predictive models of protection. Hence, the identification of the NF-κB and IFN-γ pathways provides further insight into how vaccine-mediated protection may be achieved.

Phase 1 safety and immunogenicity trial of malaria vaccine RTS,S/AS02A in adults in a hyperendemic region of western Kenya.

We conducted a phase 1 trial of candidate malaria vaccine RTS,S/AS02A in western Kenya to determine its safety and immunogenicity in healthy adults in an area hyperendemic for malaria. Twenty adults were enrolled and received RTS,S/AS02A (50 microg of RTS,S in 0.5 mL of AS02A) by intramuscular injection on a 0-, 28-, and 178-day schedule. All 60 scheduled immunizations were given, and 18 of 20 volunteers completed the last study visit on day 210. The vaccine was safe and well-tolerated. There were no vaccine-related severe adverse events. The most common solicited adverse events associated with immunization were injection site pain and headache. The geometric mean concentration of antibodies to circumsporozoite protein was 1.9 microg/mL at baseline and it increased 2-4 weeks after each dose to 16, 17.8, and 36.6 microg/mL, respectively. These safety and immunogenicity data from adults in hyperendemic Kenya are comparable to data reported earlier from two trials in west African adults in hypo-endemic and meso-endemic areas of The Gambia. We conclude that in this small study, RTS,S/AS02A is safe and similarly immunogenic in malaria-exposed African adults of different ethnicity in different transmission settings.

Development and pre-clinical analysis of a Plasmodium falciparum Merozoite Surface Protein-1(42) malaria vaccine.

Merozoite Surface Protein-1(42) (MSP-1(42)) is a leading vaccine candidate against erythrocytic malaria parasites. We cloned and expressed Plasmodium falciparum MSP-1(42) (3D7 clone) in Escherichia coli. The antigen was purified to greater than 95% homogeneity by using nickel-, Q- and carboxy-methyl (CM)-substituted resins. The final product, designated Falciparum Merozoite Protein-1 (FMP1), had endotoxin levels significantly lower than FDA standards. It was structurally correct based on binding conformation-dependent mAbs, and was stable. Functional antibodies from rabbits vaccinated with FMP1 in Freund's adjuvant inhibited parasite growth in vitro and also inhibited secondary processing of MSP-1(42). FMP1 formulated with GlaxoSmithKline Biologicals (GSK) adjuvant, AS02A or alum was safe and immunogenic in rhesus (Macaca mulatta) monkeys.

Safety and immunogenicity of rts,s+trap malaria vaccine, formulated in the as02a adjuvant system, in infant rhesus monkeys.

Malaria vaccine RTS,S combined with thrombospondin-related anonymous protein (TRAP) and formulated with AS02A (RTS,S+TRAP/AS02A) is safe and immunogenic in adult humans and rhesus monkeys (Macaca mulatta). Here, RTS,S+TRAP/AS02A was administered on a 0-, 1-, and 3-month schedule to three cohorts of infant monkeys, along with adult comparators. Cohort 1 evaluated 1/5, 1/2, and full adult doses, with the first dose administration at one month of age; cohort 2 monkeys received full adult doses, with the first dose administration at one versus three months of age; and, cohort 3 compared infants gestated in mothers with or without previous RTS,S/AS02A immunization. Immunization site reactogenicity was mild. Some infants, including the phosphate-buffered saline only recipient, developed transient iron-deficiency anemia, which is considered a result of repeated phlebotomies. All RTS,S+TRAP/AS02A regimens induced vigorous antibody responses that persisted through 12 weeks after the last vaccine dose. Modest lymphoproliferative and ELISPOT (interferon-gamma and interleukin-5) responses, particularly to TRAP, approximated adult comparators. RTS,S+TRAP/AS02A was safe and well tolerated. Vigorous antibody production and modest, selective cell-mediated immune responses suggest that RTS,S+TRAP/AS02A may be immunogenic in human infants.

Update on the clinical development of candidate malaria vaccines.

The recent availability of significantly increased levels of funding for unmet medical needs in the developing world, made available by newly created public-private-partnerships, has proven to be a powerful driver for stimulating clinical development of candidate vaccines for malaria. This new way forward promises to greatly increase the likelihood of bringing a safe and effective vaccine to licensure. The investigators bring together important published and unpublished information that illuminates the status of malaria vaccine development. They focus their comments on those candidate vaccines that are currently in or expected to enter clinical trials in the next 12 months.

Sequential Phase 1 and Phase 2 randomized, controlled trials of the safety, immunogenicity and efficacy of combined pre-erythrocytic vaccine antigens RTS,S and TRAP formulated with AS02 Adjuvant System in healthy, malaria naïve adults.

In an attempt to improve the efficacy of the candidate malaria vaccine RTS,S/AS02, two studies were conducted in 1999 in healthy volunteers of RTS,S/AS02 in combination with recombinant Plasmodium falciparum thrombospondin-related anonymous protein (TRAP). In a Phase 1 safety and immunogenicity study, volunteers were randomized to receive TRAP/AS02 (N=10), RTS,S/AS02 (N=10), or RTS,S+TRAP/AS02 (N=20) at 0, 1 and 6-months. In a Phase 2 challenge study, subjects were randomized to receive either RTS,S+TRAP/AS02 (N=25) or TRAP/AS02 (N=10) at 0 and 1-month, or to a challenge control group (N=8). In both studies, the combination vaccine had an acceptable safety profile and was acceptably tolerated. Antigen-specific antibodies, lymphoproliferative responses, and IFN-γ production by ELISPOT assay elicited with the combination vaccine were qualitatively similar to those generated by the single component vaccines. However, post-dose 2 anti-CS antibodies in the RTS,S+TRAP/AS02 vaccine recipients were lower than in the RTS,S/AS02 vaccine recipients. After challenge, 10 of 11 RTS,S+TRAP/AS02 vaccinees, 5 of 5 TRAP/AS02 vaccinees, and 8 of 8 infectivity controls developed parasitemia, with median pre-patent periods of 13.0, 11.0, and 12.0 days, respectively. The absence of any prevention or delay of parasitemia by TRAP/AS02 suggests no apparent added value of TRAP/AS02 as a candidate vaccine. The absence of significant protection or delay of parasitemia in the 11 RTS,S+TRAP/AS02 vaccine recipients contrasts with previous 2 dose studies of RTS,S/AS02. The small sample size did not permit identifying statistically significant differences between the study arms. However, we speculate, within the constraints of the challenge study, that the presence of the TRAP antigen may have interfered with the vaccine efficacy previously observed with this regimen of RTS,S/AS02, and that any future TRAP-based vaccines should consider employing alternative vaccine platforms.

Significance of infectious agents in colorectal cancer development.

Colorectal cancer (CRC) is a major burden to healthcare systems worldwide accounting for approximately one million of new cancer cases worldwide. Even though, CRC mortality has decreased over the last 20 years, it remains the third most common cause of cancer-related mortality, accounting for approximately 600,000 deaths in 2008 worldwide. A multitude of risk factors have been linked to CRC, including hereditary factors, environmental factors and inflammatory syndromes affecting the gastrointestinal tract. Recently, various pathogens were added to the growing list of risk factors for a number of common epithelial cancers, but despite the multitude of correlative studies, only suggestions remain about the possible relationship between selected viruses and bacteria of interest and the CRC risk. United States military service members are exposed to various risk factors impacting the incidence of cancer development. These exposures are often different from that of many sectors of the civilian population. Thereby, cancer risk identification, screening and early detection are imperative for both the military health care beneficiaries and the population as a whole. In this review, we will focus on several pathogens and their potential roles in development of CRC, highlighting the clinical trials evaluating this correlation and provide our personal opinion about the importance of risk reduction, health promotion and disease prevention for military health care beneficiaries.

The relationship between RTS,S vaccine-induced antibodies, CD4⁺ T cell responses and protection against Plasmodium falciparum infection.

Vaccination with the pre-erythrocytic malaria vaccine RTS,S induces high levels of antibodies and CD4(+) T cells specific for the circumsporozoite protein (CSP). Using a biologically-motivated mathematical model of sporozoite infection fitted to data from malaria-naive adults vaccinated with RTS,S and subjected to experimental P. falciparum challenge, we characterised the relationship between antibodies, CD4(+) T cell responses and protection from infection. Both anti-CSP antibody titres and CSP-specific CD4(+) T cells were identified as immunological surrogates of protection, with RTS,S induced anti-CSP antibodies estimated to prevent 32% (95% confidence interval (CI) 24%-41%) of infections. The addition of RTS,S-induced CSP-specific CD4(+) T cells was estimated to increase vaccine efficacy against infection to 40% (95% CI, 34%-48%). This protective efficacy is estimated to result from a 96.1% (95% CI, 93.4%-97.8%) reduction in the liver-to-blood parasite inoculum, indicating that in volunteers who developed P. falciparum infection, a small number of parasites (often the progeny of a single surviving sporozoite) are responsible for breakthrough blood-stage infections.