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.

New Host-Directed Therapeutics for the Treatment of Clostridioides difficile Infection.

Frequent and excessive use of antibiotics primes patients to infection (CDI), which leads to fatal pseudomembranous colitis, with limited treatment options. In earlier reports, we used a drug repurposing strategy and identified amoxapine (an antidepressant), doxapram (a breathing stimulant), and trifluoperazine (an antipsychotic), which provided significant protection to mice against lethal infections with several pathogens, including However, the mechanisms of action of these drugs were not known. Here, we provide evidence that all three drugs offered protection against experimental CDI by reducing bacterial burden and toxin levels, although the drugs were neither bacteriostatic nor bactericidal in nature and had minimal impact on the composition of the microbiota.

T6SS and ExoA of flesh-eating in peritonitis and necrotizing fasciitis during mono- and polymicrobial infections.

An earlier report described a human case of necrotizing fasciitis (NF) caused by mixed infection with 4 strains (NF1-NF4). While the NF2, NF3, and NF4 strains were clonal and possessed exotoxin A (ExoA), the NF1 strain was determined to be phylogenetically distinct, harboring a unique type 6 secretion system (T6SS) effector (TseC). During NF1 and NF2 mixed infection, only NF1 disseminated, while NF2 was rapidly killed by a contact-dependent mechanism and macrophage phagocytosis, as was demonstrated by using in vitro models.

Student Evaluation of Interprofessional Experiences between Medical and Graduate Biomedical Students.

Background: Interprofessional education (IPE) has fostered increased collaboration and appreciation for different disciplines among health professionals but has yet to be established in a translational research setting. Interprofessional experiences (IPEx) implemented early in student training could increase translational research productivity.

Methods And Findings: Ten students involved in an IPE curriculum wrote autoethnographic accounts that were coded and emergent themes were grouped through constant comparative analysis.

Combating Multidrug-Resistant Pathogens with Host-Directed Nonantibiotic Therapeutics.

Earlier, we reported that three Food and Drug Administration-approved drugs, trifluoperazine (TFP; an antipsychotic), amoxapine (AXPN; an antidepressant), and doxapram (DXP; a breathing stimulant), identified from an murine macrophage cytotoxicity screen, provided mice with 40 to 60% protection against pneumonic plague when administered at the time of infection for 1 to 3 days. In the present study, the therapeutic potential of these drugs against pneumonic plague in mice was further evaluated when they were administered at up to 48 h postinfection. While the efficacy of TFP was somewhat diminished as treatment was delayed to 24 h, the protection of mice with AXPN and DXP increased as treatment was progressively delayed to 24 h.

Identification of New Virulence Factors and Vaccine Candidates for .

Earlier, we reported the identification of new virulence factors/mechanisms of using an signature-tagged mutagenesis (STM) screening approach. From this screen, the role of , which encodes an ATP-binding protein of ribose transport system, and , an essential component of the type VI secretion system (T6SS), were evaluated in mouse models of plague and confirmed to be important during infection. However, many of the identified genes from the screen remained uncharacterized.

A Bivalent Anthrax-Plague Vaccine That Can Protect against Two Tier-1 Bioterror Pathogens, and .

Bioterrorism remains as one of the biggest challenges to global security and public health. Since the deadly anthrax attacks of 2001 in the United States, and , the causative agents of anthrax and plague, respectively, gained notoriety and were listed by the CDC as Tier-1 biothreat agents. Currently, there is no Food and Drug Administration-approved vaccine against either of these threats for mass vaccination to protect general public, let alone a bivalent vaccine.

New Insights into Autoinducer-2 Signaling as a Virulence Regulator in a Mouse Model of Pneumonic Plague.

The family members, including the infamous , the causative agent of plague, have a highly conserved interbacterial signaling system that is mediated by the autoinducer-2 (AI-2) quorum-sensing molecule. The AI-2 system is implicated in regulating various bacterial virulence genes in diverse environmental niches. Deletion of the gene encoding the synthetic enzyme for the AI-2 substrate, , leads to either no significant change or, paradoxically, an increase in bacterial virulence.

Protective Immunity Elicited by Oral Immunization of Mice with Serovar Typhimurium Braun Lipoprotein (Lpp) and Acetyltransferase (MsbB) Mutants.

We evaluated the extent of attenuation and immunogenicity of the Δ and Δ Δ mutants of serovar Typhimurium when delivered to mice by the oral route. These mutants were deleted either for the Braun lipoprotein genes ( and ) or in combination with the gene, which encodes an acetyltransferase required for lipid A modification of lipopolysaccharide. Both the mutants were attenuated (100% animal survival) and triggered robust innate and adaptive immune responses.

Immunisation of two rodent species with new live-attenuated mutants of CO92 induces protective long-term humoral- and cell-mediated immunity against pneumonic plague.

We showed recently that the live-attenuated Δ Δ Δ and Δ Δ mutants of CO92 provided short-term protection to mice against developing subsequent lethal pneumonic plague. These mutants were either deleted for genes encoding Braun lipoprotein (Lpp), an acetyltransferase (MsbB) and the attachment invasion locus (Ail) (Δ Δ Δ) or contained a modified version of the gene with diminished virulence (Δ Δ). Here, long-term immune responses were first examined after intramuscular immunisation of mice with the above-mentioned mutants, as well as the newly constructed Δ Δ Δ mutant, deleted for the plasminogen-activator protease () gene instead of .

A Replication-Defective Human Type 5 Adenovirus-Based Trivalent Vaccine Confers Complete Protection against Plague in Mice and Nonhuman Primates.

Currently, no plague vaccine exists in the United States for human use. The capsular antigen (Caf1 or F1) and two type 3 secretion system (T3SS) components, the low-calcium-response V antigen (LcrV) and the needle protein YscF, represent protective antigens of Yersinia pestis We used a replication-defective human type 5 adenovirus (Ad5) vector and constructed recombinant monovalent and trivalent vaccines (rAd5-LcrV and rAd5-YFV) that expressed either the codon-optimized lcrV or the fusion gene designated YFV (consisting of ycsF, caf1, and lcrV). Immunization of mice with the trivalent rAd5-YFV vaccine by either the intramuscular (i.

New Role for FDA-Approved Drugs in Combating Antibiotic-Resistant Bacteria.

Antibiotic resistance in medically relevant bacterial pathogens, coupled with a paucity of novel antimicrobial discoveries, represents a pressing global crisis. Traditional drug discovery is an inefficient and costly process; however, systematic screening of Food and Drug Administration (FDA)-approved therapeutics for other indications in humans offers a rapid alternative approach. In this study, we screened a library of 780 FDA-approved drugs to identify molecules that rendered RAW 264.

Cross-talk among flesh-eating Aeromonas hydrophila strains in mixed infection leading to necrotizing fasciitis.

Necrotizing fasciitis (NF) caused by flesh-eating bacteria is associated with high case fatality. In an earlier study, we reported infection of an immunocompetent individual with multiple strains of Aeromonas hydrophila (NF1-NF4), the latter three constituted a clonal group whereas NF1 was phylogenetically distinct. To understand the complex interactions of these strains in NF pathophysiology, a mouse model was used, whereby either single or mixed A.

High-throughput, signature-tagged mutagenic approach to identify novel virulence factors of Yersinia pestis CO92 in a mouse model of infection.

The identification of new virulence factors in Yersinia pestis and understanding their molecular mechanisms during an infection process are necessary in designing a better vaccine or to formulate an appropriate therapeutic intervention. By using a high-throughput, signature-tagged mutagenic approach, we created 5,088 mutants of Y. pestis strain CO92 and screened them in a mouse model of pneumonic plague at a dose equivalent to 5 50% lethal doses (LD50) of wild-type (WT) CO92.

Combinational deletion of three membrane protein-encoding genes highly attenuates yersinia pestis while retaining immunogenicity in a mouse model of pneumonic plague.

Previously, we showed that deletion of genes encoding Braun lipoprotein (Lpp) and MsbB attenuated Yersinia pestis CO92 in mouse and rat models of bubonic and pneumonic plague. While Lpp activates Toll-like receptor 2, the MsbB acyltransferase modifies lipopolysaccharide. Here, we deleted the ail gene (encoding the attachment-invasion locus) from wild-type (WT) strain CO92 or its lpp single and Δlpp ΔmsbB double mutants.