scholarly journals Characterization of a new Leishmania major isolate for use in a controlled human infection model

2020 ◽  
Author(s):  
Helen Ashwin ◽  
Jovana Sadlova ◽  
Barbora Vojtkova ◽  
Tomas Becvar ◽  
Patrick Lypaczewski ◽  
...  
Keyword(s):  
Leishmania Major ◽  
Vaccine Development ◽  
Human Infection ◽  
Sand Fly ◽  
Infection Model ◽  
Phase 3 ◽  
Pivotal Phase ◽  
Infection Models

AbstractLeishmaniasis is widely regarded as a vaccine-preventable disease, but the costs required to reach pivotal Phase 3 studies and uncertainty about which candidate vaccines should be progressed into human studies significantly limits progress in vaccine development for this neglected tropical disease. Controlled human infection models (CHIM) provide a pathway for accelerating vaccine development and to more fully understand disease pathogenesis and correlates of protection. Here, we describe the isolation, characterization and GMP manufacture of a new clinical isolate of Leishmania major. Two fresh isolates of L. major from Israel were initially compared by genome sequencing, in vivo infectivity and drug sensitivity in mice, and development and transmission competence in sand flies, allowing one (L. major_MRC-02) to be selected for GMP production. This study addresses a major roadblock in the development of vaccines for leishmaniasis, providing a key resource for CHIM studies of sand fly transmitted cutaneous leishmaniasis.

scholarly journals Consensus Report on Shigella Controlled Human Infection Model: Introduction and Overview

2019 ◽  
Vol 69 (Supplement_8) ◽  
pp. S577-S579 ◽  
Author(s):  
Calman A MacLennan ◽  
Anastazia Older Aguilar ◽  
A Duncan Steele
Keyword(s):  
Best Practices ◽  
Vaccine Development ◽  
Disease Process ◽  
The United States ◽  
Human Infection ◽  
Infection Model ◽  
Infectious Agents ◽  
Vaccine Candidates ◽  
Infection Models ◽  
Consensus Report

Abstract In recent years, controlled human infection models (CHIMs) have become available for a range of infectious agents and have proved invaluable for understanding the disease process, pathogenesis, and mechanisms of immunity. CHIM studies have also contributed significantly to advancing development of a number of vaccines by providing an indication of vaccine efficacy. The Shigella CHIM has been established in 3 sites in the United States, and it is likely that the CHIM will play an important regulatory role for advancing the range of Shigella vaccine candidates that are currently in development. This supplement describes the harmonization of best practices across sites, with a view to maximizing the contribution that CHIM studies can make to Shigella vaccine development.

scholarly journals Establishment of a Controlled Human Infection Model with a Lyophilized Strain of Shigella sonnei 53G

mSphere ◽  
2020 ◽  
Vol 5 (5) ◽  
Author(s):  
Robert W. Frenck ◽  
Michelle Dickey ◽  
Akamol E. Suvarnapunya ◽  
Lakshmi Chandrasekaran ◽  
Robert W. Kaminski ◽  
...  
Keyword(s):  
Vaccine Development ◽  
Human Infection ◽  
Shigella Sonnei ◽  
World Health ◽  
Infection Model ◽  
Sample Collection ◽  
Open Label ◽  
Content Type ◽  
Infection Models ◽  
Study Results

ABSTRACT Controlled human infection models (CHIMs) are useful for vaccine development. To improve on existing models, we developed a CHIM using a lyophilized preparation of Shigella sonnei strain 53G produced using current good manufacturing practice (cGMP). Healthy adults were enrolled in an open-label dose-ranging study. Following administration of a dose of rehydrated S. sonnei strain 53G, subjects were monitored for development of disease. The first cohort received 500 CFU of 53G, and dosing of subsequent cohorts was based on results from the previous cohort. Subjects were administered ciprofloxacin on day 5 and discharged home on day 8. Subjects returned as outpatients for clinical checks and sample collection. Attack rates increased as the dose of S. sonnei was increased. Among those receiving the highest dose (1,760 CFU), 70% developed moderate to severe diarrhea, 50% had dysentery, and 40% had fever. Antilipopolysaccharide responses were observed across all cohorts. An S. sonnei CHIM using a lyophilized lot of strain 53G was established. A dose in the range of 1,500 to 2,000 CFU of 53G was selected as the dose for future challenge studies using this product. This model will enable direct comparison of study results between institutions and ensure better consistency over time in the challenge inoculum. IMPORTANCE Controlled human infection models (CHIMs) are invaluable tools utilized to understand the human response to infection, potentially leading to protective immune mechanisms and allowing efficacy testing of enteric countermeasures, including vaccines, antibiotics, and other products. The development of an improved Shigella CHIM for both Shigella sonnei and Shigella flexneri is consistent with international efforts, supported by international donors and the World Health Organization, focused on standardizing Shigella CHIMs and using them to accelerate Shigella vaccine development. The use of lyophilized Shigella challenge strains rather than plate-grown inoculum preparations is considered an important step forward in the standardization process. Furthermore, the results of studies such as this justify the development of lyophilized preparations for additional epidemiologically important S. flexneri serotypes, including S. flexneri 3a and S. flexneri 6.

scholarly journals A clinical study to optimise a sand fly biting protocol for use in a controlled human infection model of cutaneous leishmaniasis (the FLYBITE study)

2021 ◽  
Vol 6 ◽  
pp. 168
Author(s):  
Vivak Parkash ◽  
Helen Ashwin ◽  
Jovana Sadlova ◽  
Barbora Vojtkova ◽  
Georgina Jones ◽  
...  
Keyword(s):  
Focus Groups ◽  
Leishmania Major ◽  
Human Infection ◽  
Sand Fly ◽  
Infection Model ◽  
Sand Flies ◽  
Serious Adverse Events ◽  
Natural Sand ◽  
Early Evaluation ◽  
Significant Difference

Background: Leishmaniasis is a globally important yet neglected parasitic disease transmitted by phlebotomine sand flies. With new candidate vaccines in or near the clinic, a controlled human challenge model (CHIM) using natural sand fly challenge would provide a method for early evaluation of prophylactic efficacy. Methods: We evaluated the biting frequency and adverse effects resulting from exposure of human volunteers to bites of either Phlebotomus papatasi or P. duboscqi, two natural vectors of Leishmania major. 12 healthy participants were recruited (mean age 40.2 ± 11.8 years) with no history of significant travel to regions where L. major-transmitting sand flies are prevalent. Participants were assigned to either vector by 1:1 allocation and exposed to five female sand flies for 30 minutes in a custom biting chamber. Bite frequency was recorded to confirm a bloodmeal was taken. Participant responses and safety outcomes were monitored using a visual analogue scale (VAS), clinical examination, and blood biochemistry. Focus groups were subsequently conducted to explore participant acceptability. Results: All participants had at least one successful sand fly bite with none reporting any serious adverse events, with median VAS scores of 0-1/10 out to day 21 post-sand fly bite. Corresponding assessment of sand flies confirmed that for each participant at least 1/5 sand flies had successfully taken a bloodmeal (overall mean 3.67±1.03 bites per participant). There was no significant difference between P. papatasi and P. duboscqi in the number of bites resulting from 5 sand flies applied to human participants (3.3±0.81 vs 3.00±1.27 bites per participant; p=0.56).  In the two focus groups (n=5 per group), themes relating to positive participant-reported experiences of being bitten and the overall study, were identified. Conclusions: These results validate a protocol for achieving successful sand fly bites in humans that is safe, well-tolerated and acceptable for participants. Clinicaltrials.gov registration: NCT03999970 (27/06/2019)

scholarly journals A Comparison of Murine and Human Immunoproteomes of Helicobacter pylori Validates the Preclinical Murine Infection Model for Antigen Screening

2002 ◽  
Vol 70 (11) ◽  
pp. 6494-6498 ◽  
Author(s):  
Dirk Bumann ◽  
Petra Holland ◽  
Frank Siejak ◽  
Jan Koesling ◽  
Nicolas Sabarth ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Vaccine Development ◽  
Protein Composition ◽  
Infection Model ◽  
Host Immune System ◽  
High Agreement ◽  
Infection Models ◽  
H Pylori ◽  
Human Infections

ABSTRACT Preclinical mouse infection models are widely used for Helicobacter vaccine development, but how well such models mimic important aspects of human infections is unknown. A comparison of Helicobacter pylori immunoproteomes of infected mice with previously reported patient data reveals a high agreement in the antigens recognized, suggesting that H. pylori in vivo protein composition and recognition by the host immune system are comparable in mice and humans. Murine Helicobacter models may thus be valid to screen antigens for human vaccination.

scholarly journals Type VI secretion system and its effectors PdpC, PdpD and OpiA contribute to Francisella virulence in Galleria mellonella larvae

2021 ◽  
Author(s):  
Maj Brodmann ◽  
Sophie Schnider ◽  
Marek Basler
Keyword(s):  
Galleria Mellonella ◽  
Response Regulator ◽  
Infection Model ◽  
Type Vi Secretion System ◽  
Infectious Dose ◽  
Infection Models

Francisella tularensis causes the deadly zoonotic disease tularemia in humans and is able to infect a broad range of organisms including arthropods, which are thought to play a major role in Francisella transmission. However, while mammalian in vitro and in vivo infection models are widely used to investigate Francisella pathogenicity, a detailed characterization of the major Francisella virulence factor, a non-canonical T6SS, in an arthropod in vivo infection model is missing. Here we use Galleria mellonella larvae to analyze the role of the Francisella T6SS and its corresponding effectors in F. novicida virulence. We report that G. mellonella larvae killing depends on the functional T6SS and infectious dose. In contrast to other mammalian in vivo infection models, even one of PdpC, PdpD or OpiA T6SS effectors is sufficient to kill G. mellonella larvae while sheath recycling by ClpB is dispensable. We further demonstrate that treatment by polyethylene glycol (PEG) activates Francisella T6SS in liquid culture and that this is independent of the response regulator PmrA. PEG-activated IglC secretion is dependent on T6SS structural component PdpB but independent of putative effectors PdpC, PdpD, AnmK and OpiB1-3. The results of larvae infection and secretion assay suggest that AnmK, a putative T6SS component with unknown function, interferes with OpiA-mediated toxicity but not with general T6SS activity. We establish that the easy-to-use G. mellonella larvae infection model provides new insights into function of T6SS and pathogenesis of Francisella.

scholarly journals Identification and Characterization of the PutP Proline Permease That Contributes to In Vivo Survival ofStaphylococcus aureus in Animal Models

1998 ◽  
Vol 66 (2) ◽  
pp. 567-572 ◽  
Author(s):  
William R. Schwan ◽  
Silvija N. Coulter ◽  
Eva Y. W. Ng ◽  
Michael H. Langhorne ◽  
Heather D. Ritchie ◽  
...  
Keyword(s):  
Animal Models ◽  
Reading Frame ◽  
High Affinity ◽  
Wound Model ◽  
Infection Models ◽  
Uptake Assay ◽  
Entire Open Reading Frame ◽  
In Vivo Growth

ABSTRACT Staphylococcus aureus is an important pathogen of humans and other animals, causing bacteremia, abscesses, endocarditis, and other infectious syndromes. A signature-tagged mutagenesis (STM) system was adapted for use in studying the genes required for in vivo survival of S. aureus. An STM library was ultimately created in S. aureus RN6390, with Tn917 being used to create the transposon mutations. Pools of S. aureusRN6390 mutants were screened in mouse abscess, bacteremia, and wound infection models for growth attenuation after in vivo passage. One of the mutants that was identified displayed marked attenuation following large-pool screening in all three animal models, which was confirmed in bacteremia and endocarditis models of infection with a smaller pool of mutants. Sequence analysis of the entire open reading frame showed a 99% identity to the high-affinity proline permease (putP) gene characterized in another strain of S. aureus. In wound and murine abscess infection models, the putP mutant was approximately 10-fold more attenuated than was wild-type strain RN6390. Another S. aureus strain transduced with theputP mutation also displayed an attenuated phenotype after passage in the wound model. A [3H]proline uptake assay showed that less proline was specifically transported into theputP mutant than into strain RN6390. The reduced viability of the bacteria possessing the mutation in the S. aureushigh-affinity proline permease suggests that proline scavenging by the bacteria is important for in vivo growth and proliferation and that analogs of proline may serve as potential antistaphylococcal therapeutic agents.

scholarly journals EnterotoxigenicE. colivirulence gene regulation in human infections

2018 ◽  
Vol 115 (38) ◽  
pp. E8968-E8976 ◽  
Author(s):  
Alexander A. Crofts ◽  
Simone M. Giovanetti ◽  
Erica J. Rubin ◽  
Frédéric M. Poly ◽  
Ramiro L. Gutiérrez ◽  
...  
Keyword(s):  
Gene Expression ◽  
Virulence Factor ◽  
Virulence Gene ◽  
Human Infection ◽  
Anaerobic Growth ◽  
Infection Model ◽  
Low Oxygen ◽  
Virulence Gene Expression ◽  
Factor Expression

EnterotoxigenicEscherichia coli(ETEC) is a global diarrheal pathogen that utilizes adhesins and secreted enterotoxins to cause disease in mammalian hosts. Decades of research on virulence factor regulation in ETEC has revealed a variety of environmental factors that influence gene expression, including bile, pH, bicarbonate, osmolarity, and glucose. However, other hallmarks of the intestinal tract, such as low oxygen availability, have not been examined. Further, determining how ETEC integrates these signals in the complex host environment is challenging. To address this, we characterized ETEC’s response to the human host using samples from a controlled human infection model. We found ETEC senses environmental oxygen to globally influence virulence factor expression via the oxygen-sensitive transcriptional regulator fumarate and nitrate reduction (FNR) regulator. In vitro anaerobic growth replicates the in vivo virulence factor expression profile, and deletion offnrin ETEC strain H10407 results in a significant increase in expression of all classical virulence factors, including the colonization factor antigen I (CFA/I) adhesin operon and both heat-stable and heat-labile enterotoxins. These data depict a model of ETEC infection where FNR activity can globally influence virulence gene expression, and therefore proximity to the oxygenated zone bordering intestinal epithelial cells likely influences ETEC virulence gene expression in vivo. Outside of the host, ETEC biofilms are associated with seasonal ETEC epidemics, and we find FNR is a regulator of biofilm production. Together these data suggest FNR-dependent oxygen sensing in ETEC has implications for human infection inside and outside of the host.

scholarly journals Characterization of Novel Antimicrobial Peptoids

1999 ◽  
Vol 43 (6) ◽  
pp. 1429-1434 ◽  
Author(s):  
Bob Goodson ◽  
Anton Ehrhardt ◽  
Simon Ng ◽  
John Nuss ◽  
Kirk Johnson ◽  
...  
Keyword(s):  
Antibacterial Activities ◽  
Membrane Disruption ◽  
Infection Model ◽  
Gram Negative Bacteria ◽  
Positional Isomers ◽  
Bacterial Growth Inhibition ◽  
Alpha Carbon

ABSTRACT Peptoids differ from peptides in that peptoids are composed of N-substituted rather than alpha-carbon-substituted glycine units. In this paper we report the in vitro and in vivo antibacterial activities of several antibacterial peptoids discovered by screening combinatorial chemistry libraries for bacterial growth inhibition. In vitro, the peptoid CHIR29498 and some of its analogues were active in the range of 3 to 12 μg/ml against a panel of gram-positive and gram-negative bacteria which included isolates which were resistant to known antibiotics. Peptoid antimicrobial activity againstStaphylococcus aureus was rapid, bactericidal, and independent of protein synthesis. β-Galactosidase and propidium iodide leakage assays indicated that the membrane is the most likely target of activity. Positional isomers of an active peptoid were also active, consistent with a mode of action, such as membrane disruption, that does not require a specific fit between the molecule and its target. In vivo, CHIR29498 protected S. aureus-infected mice in a simple infection model.

scholarly journals Some Epidemiological Aspects of Cutaneous Leishmaniasis in a New Focus, Central Iran

2015 ◽  
Vol 2015 ◽  
pp. 1-5 ◽  
Author(s):  
M. R. Yaghoobi-Ershadi ◽  
N. Marvi-Moghadam ◽  
R. Jafari ◽  
A. A. Akhavan ◽  
H. Solimani ◽  
...  
Keyword(s):  
Cutaneous Leishmaniasis ◽  
Primary Schools ◽  
Leishmania Major ◽  
Reservoir Host ◽  
Human Infection ◽  
Native People ◽  
Sand Fly ◽  
Animal Reservoir ◽  
Rural Districts ◽  
Tatera Indica

Following the epidemic of cutaneous leishmaniasis in Khatam County, Yazd Province, this study was carried out to determine vector, and animal reservoir host(s) and investigate the human infection during 2005-2006. Four rural districts where the disease had higher prevalence were selected. Sticky paper traps were used to collect sand flies during April to November, biweekly. Meanwhile rodents were captured using Sherman traps from August to November. Households and primary schools were visited and examined for human infection in February 2006. The parasite was detected by RAPD-PCR method. The rate of ulcers and scars among the inhabitants was 4.8% and 9.8%, respectively. Three rodent species were captured during the study:Meriones libycus, Rhombomys opimus, andTatera indica. Six sand fly species were also collected and identified; among themPhlebotomus papatasihad the highest frequency.Leishmania majorwas detected as the agent of the disease in the area. It was detected fromR. opimusand native people.

scholarly journals Use of In Vivo-Induced Antigen Technology for Identification of Escherichia coli O157:H7 Proteins Expressed during Human Infection

2005 ◽  
Vol 73 (5) ◽  
pp. 2665-2679 ◽  
Author(s):  
Manohar John ◽  
Indira T. Kudva ◽  
Robert W. Griffin ◽  
Allen W. Dodson ◽  
Bethany McManus ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Vaccine Development ◽  
Human Infection ◽  
Escherichia Coli O157 ◽  
Standard Laboratory ◽  
E Coli ◽  
Phase Culture ◽  
Stool Specimens

ABSTRACT Using in vivo-induced antigen technology (IVIAT), a modified immunoscreening technique that circumvents the need for animal models, we directly identified immunogenic Escherichia coli O157:H7 (O157) proteins expressed either specifically during human infection but not during growth under standard laboratory conditions or at significantly higher levels in vivo than in vitro. IVIAT identified 223 O157 proteins expressed during human infection, several of which were unique to this study. These in vivo-induced (ivi) proteins, encoded by ivi genes, mapped to the backbone, O islands (OIs), and pO157. Lack of in vitro expression of O157-specific ivi proteins was confirmed by proteomic analysis of a mid-exponential-phase culture of E. coli O157 grown in LB broth. Because ivi proteins are expressed in response to specific cues during infection and might help pathogens adapt to and counter hostile in vivo environments, those identified in this study are potential targets for drug and vaccine development. Also, such proteins may be exploited as markers of O157 infection in stool specimens.

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