A novel outer membrane vesicle adjuvant improves vaccine protection against Bordetella pertussis.

Pertussis is a vaccine-preventable respiratory disease caused by the Gram negative coccobacillus Bordetella pertussis. The licensed acellular pertussis (aP) vaccines protect against disease but do not prevent bacterial colonization and transmission. Here, we developed and tested an intranasal vaccine composed of aP antigens combined with T-vant, a novel adjuvant derived from bacterial outer membrane vesicles, that elicits both mucosal and systemic immune responses.

Non-mucosal vaccination strategies to enhance mucosal immunity.

The SARS-CoV-2 pandemic has highlighted the need for improved vaccines that can elicit long-lasting mucosal immunity. Although mucosal delivery of vaccines represents a plausible method to enhance mucosal immunity, recent studies utilizing intradermal vaccine delivery or incorporation of unique adjuvants suggest that mucosal immunity may be achieved by vaccination via non-mucosal routes. In this expert insight, we highlight emerging evidence from pre-clinical studies that warrant further mechanistic investigation to improve next-generation vaccines against mucosal pathogens, especially those with pandemic potential.

Establishment of isotype-switched, antigen-specific B cells in multiple mucosal tissues using non-mucosal immunization.

Although most pathogens infect the human body via mucosal surfaces, very few injectable vaccines can specifically target immune cells to these tissues where their effector functions would be most desirable. We have previously shown that certain adjuvants can program vaccine-specific helper T cells to migrate to the gut, even when the vaccine is delivered non-mucosally. It is not known whether this is true for antigen-specific B cell responses.

Optimization of Host Cell-Compatible, Antimicrobial Peptides Effective against Biofilms and Clinical Isolates of Drug-Resistant Bacteria.

Here, we describe the continued synthetic molecular evolution of a lineage of host-compatible antimicrobial peptides (AMP) intended for the treatment of wounds infected with drug-resistant, biofilm-forming bacteria. The peptides tested are variants of an evolved AMP called d-amino acid CONsensus with Glycine Absent (d-CONGA), which has excellent antimicrobial activities and . In this newest generation of rational d-CONGA variants, we tested multiple sequence-structure-function hypotheses that had not been tested in previous generations.

The role of the hypermutator phenotype on the shift from acute to chronic virulence during respiratory infection.

Chronic respiratory infection (CRI) with (Pa) presents many unique challenges that complicate treatment. One notable challenge is the hypermutator phenotype which is present in up to 60% of sampled CRI patient isolates. Hypermutation can be caused by deactivating mutations in DNA mismatch repair (MMR) genes including , , and .

SARS-CoV-2 Epitopes following Infection and Vaccination Overlap Known Neutralizing Antibody Sites.

Identification of epitopes targeted following virus infection or vaccination can guide vaccine design and development of therapeutic interventions targeting functional sites, but can be laborious. Herein, we employed peptide microarrays to map linear peptide epitopes (LPEs) recognized following SARS-CoV-2 infection and vaccination. LPEs detected by nonhuman primate (NHP) and patient IgMs after SARS-CoV-2 infection extensively overlapped, localized to functionally important virus regions, and aligned with reported neutralizing antibody binding sites.

The Remarkable Innate Resistance of Burkholderia bacteria to Cationic Antimicrobial Peptides: Insights into the Mechanism of AMP Resistance.

Gram-negative bacteria belonging to the genus Burkholderia are remarkably resistant to broad-spectrum, cationic, antimicrobial peptides (AMPs). It has been proposed that this innate resistance is related to changes in the outer membrane lipopolysaccharide (OM LPS), including the constitutive, essential modification of outer membrane Lipid A phosphate groups with cationic 4-amino-4-deoxy-arabinose. This modification reduces the overall negative charge on the OM LPS which may change the OM structure and reduce the binding, accumulation, and permeation of cationic AMPs.

Vaccination to Prevent Bloodstream Infections.

The bacterium (Pa) is ubiquitous in the environment and causes opportunistic infections in humans. Pa is increasingly becoming one of the most difficult to treat microorganisms due to its intrinsic and acquired resistance to multiple antibiotics. The World Health Organization estimates that at least 700,000 people die each year from drug resistant microbial infections and have listed Pa as one of three bacterial species for which there is the most critical need for the development of novel therapeutics.

Mycobacterium bovis bacille Calmette-Guerin-derived extracellular vesicles as an alternative to live BCG immunotherapy.

For over 40 years, the gold standard treatment for non-muscular invasive bladder cancer (NMIBC) has been repeated administration of Mycobacterium bovis bacille Calmette-Guerin (BCG). Upon administration, BCG initiates a cascade of immunological events that lead to the recruitment of immune cells to the bladder that eliminates NMIBC cells in a multi-mechanistic, yet incompletely defined manner. Despite its effectiveness, live BCG immunotherapy is often impacted by limited supply and availability and can cause rare but serious side effects.

Inhibition of Streptococcus mutans biofilms with bacterial-derived outer membrane vesicles.

Background: Biofilms are microbial communities surrounded by a self-produced extracellular matrix which protects them from environmental stress. Bacteria within biofilms are 10- to 1000-fold more resistant to antibiotics, making it challenging but imperative to develop new therapeutics that can disperse biofilms and eradicate infection. Gram-negative bacteria produce outer membrane vesicles (OMV) that play critical roles in communication, genetic exchange, cargo delivery, and pathogenesis.

An Outer Membrane Vesicle-Adjuvanted Oral Vaccine Protects Against Lethal, Oral Infection.

Non-typhoidal salmonellosis, caused by serovar Typhimurium is a common fecal-oral disease characterized by mild gastrointestinal distress resulting in diarrhea, chills, fever, abdominal cramps, head and body aches, nausea, and vomiting. Increasing incidences of antibiotic resistant invasive non-typhoidal infections makes this a global threat requiring novel treatment strategies including next-generation vaccines. The goal of the current study was to formulate a novel vaccine platform against infection that could be delivered orally.

Burkholderia pseudomallei OMVs derived from infection mimicking conditions elicit similar protection to a live-attenuated vaccine.

Burkholderia pseudomallei is a Gram-negative, facultative intracellular bacillus that causes the disease melioidosis. B. pseudomallei expresses a number of proteins that contribute to its intracellular survival in the mammalian host.

Bacterial-Derived Outer Membrane Vesicles are Potent Adjuvants that Drive Humoral and Cellular Immune Responses.

Discovery and development of novel adjuvants that can improve existing or next generation vaccine platforms have received considerable interest in recent years. In particular, adjuvants that can elicit both humoral and cellular immune responses would be particularly advantageous because the majority of licensed vaccines are formulated with aluminum hydroxide (alum) which predominantly promotes antibodies. We previously demonstrated that bacterial-derived outer membrane vesicles (OMV) possess inherent adjuvanticity and drive antigen-specific antibody and cellular immune responses to OMV components.

Recent Advances in the Pursuit of an Effective Vaccine.

has been a major cause of nosocomial infections for decades. The absence of an available vaccine coupled with emerging multidrug resistance has prevented the medical community from effectively controlling this human pathogen. Furthermore, the ongoing pandemic caused by SARS-CoV-2 has increased the risk of hospitalized patients developing ventilator-associated pneumonia caused by bacterial opportunists including .

Persistence and Host Immunity Are Dictated by the Anatomical Microenvironment.

The intracellular bacterial pathogen is able to evade the immune system and persist within the host. In some cases, these persistent infections are asymptomatic for long periods and represent a significant public health hazard because the hosts are potential chronic carriers, yet the mechanisms that control persistence are incompletely understood. Using a mouse model of chronic typhoid fever combined with major histocompatibility complex (MHC) class II tetramers to interrogate endogenous, -specific CD4 helper T cells, we show that certain host microenvironments may favorably contribute to a pathogen's ability to persist We demonstrate that the environment in the hepatobiliary system may contribute to the persistence of subsp.

Burkholderia thailandensis outer membrane vesicles exert antimicrobial activity against drug-resistant and competitor microbial species.

Gram-negative bacteria secrete outer membrane vesicles (OMVs) that play critical roles in intraspecies, interspecies, and bacteria-environment interactions. Some OMVs, such as those produced by Pseudomonas aeruginosa, have previously been shown to possess antimicrobial activity against competitor species. In the current study, we demonstrate that OMVs from Burkholderia thailandensis inhibit the growth of drug-sensitive and drug-resistant bacteria and fungi.

Synthetic molecular evolution of host cell-compatible, antimicrobial peptides effective against drug-resistant, biofilm-forming bacteria.

Novel classes of antibiotics and new strategies to prevent and treat infections are urgently needed because the rapid rise in drug-resistant bacterial infections in recent decades has been accompanied by a parallel decline in development of new antibiotics. Membrane permeabilizing antimicrobial peptides (AMPs) have long been considered a potentially promising, novel class of antibiotic, especially for wound protection and treatment to prevent the development of serious infections. Yet, despite thousands of known examples, AMPs have only infrequently proceeded as far as clinical trials, especially the chemically simple, linear examples.

Treatment With Novel Microbiocide Inhibits Methicillin Resistant in a Murine Wound Infection Model.

Increased prevalence of antibiotic resistance in skin and soft tissue infections is a concerning public health challenge currently facing medical science. A combinatory, broad spectrum biocidal antiseptic has been developed ("ASP") as a topically applied solution to potential resistant and polymicrobial infected wounds that may be encountered in this context. The ASP-105 designate was evaluated by determining the minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC), against different strains of methicillin-resistant (MRSA), resulting estimates of which approximated the positive control (bacitracin).

Immunological considerations in the development of vaccines.

is an opportunistic human pathogen capable of causing a wide range of potentially life-threatening infections. With multidrug-resistant infections on the rise, the need for a rationally-designed vaccine against this pathogen is critical. A number of vaccine platforms have shown promising results in pre-clinical studies, but no vaccine has successfully advanced to licensure.

Intradermal vaccination with a Pseudomonas aeruginosa vaccine adjuvanted with a mutant bacterial ADP-ribosylating enterotoxin protects against acute pneumonia.

Respiratory infections are a leading cause of morbidity and mortality globally. This is partially due to a lack of effective vaccines and a clear understanding of how vaccination route and formulation influence protective immunity in mucosal tissues such as the lung. Pseudomonas aeruginosa is an opportunistic pathogen capable of causing acute pulmonary infections and is a leading cause of hospital-acquired and ventilator-associated pneumonia.

A Burkholderia pseudomallei Outer Membrane Vesicle Vaccine Provides Cross Protection against Inhalational Glanders in Mice and Non-Human Primates.

is a Gram-negative, non-motile, facultative intracellular bacillus and the causative agent of glanders, a highly contagious zoonotic disease. is naturally resistant to multiple antibiotics and there is concern for its potential use as a bioweapon, making the development of a vaccine against of critical importance. We have previously demonstrated that immunization with multivalent outer membrane vesicles (OMV) derived from provide significant protection against pneumonic melioidosis.

Immunomodulatory effects of tick saliva on dermal cells exposed to Borrelia burgdorferi, the agent of Lyme disease.

Background: The prolonged feeding process of ixodid ticks, in combination with bacterial transmission, should lead to a robust inflammatory response at the blood-feeding site. Yet, factors present in tick saliva may down-regulate such responses, which may be beneficial to spirochete transmission. The primary goal of this study was to test the hypothesis that tick saliva, in the context of Borrelia burgdorferi, can have widespread effects on the production of immune mediators in skin.

A novel approach for emerging and antibiotic resistant infections: Innate defense regulators as an agnostic therapy.

Innate Defense Regulators (IDRs) are short synthetic peptides that target the host innate immune system via an intracellular adaptor protein which functions at key signaling nodes. In this work, further details of the mechanism of action of IDRs have been discovered. The studies reported here show that the lead clinical IDR, SGX94, has broad-spectrum activity against Gram-negative and Gram-positive bacterial infections caused by intracellular or extracellular bacteria and also complements the actions of standard of care antibiotics.

Consensus on the development of vaccines against naturally acquired melioidosis.

Several candidates for a vaccine against Burkholderia pseudomallei, the causal bacterium of melioidosis, have been developed, and a rational approach is now needed to select and advance candidates for testing in relevant nonhuman primate models and in human clinical trials. Development of such a vaccine was the topic of a meeting in the United Kingdom in March 2014 attended by international candidate vaccine developers, researchers, and government health officials. The focus of the meeting was advancement of vaccines for prevention of natural infection, rather than for protection from the organism's known potential for use as a biological weapon.