Biology subjects

Barry, E. M.

Publications and source records attributed to Barry, E. M..

3 recordsLinked to original sources

bioRxiv2021

Informing shigellosis prevention and control through pathogen genomics

Shigella spp. are the leading bacterial cause of severe childhood diarrhoea in low- and middle-income countries (LMIC), are increasingly antimicrobial resistant and have no licensed vaccine. We performed genomic analyses of 1246 systematically collected shigellae from seven LMIC to inform control and identify factors that could limit the effectiveness of current approaches. We found that S. sonnei contributes [≥]20-fold more disease than other Shigella species relative to its genomic diversity and highlight existing diversity and adaptative capacity among S. flexneri that may generate vaccine escape variants in <6 months. Furthermore, we show convergent evolution of resistance against the current recommended antimicrobial among shigellae. This demonstrates the urgent need to integrate existing genomic diversity into vaccine and treatment plans for Shigella, and other pathogens.

microbiology↗

bioRxiv2020

Oral administration of a single anti-CfaE nanobody provides broadly cross-protective immunity against major pathogenic Enterotoxigenic Escherichia coli strains

Enterotoxigenic Escherichia coli (ETEC) is estimated to cause approximately 380,000 deaths annually during sporadic or epidemic outbreaks worldwide. There is currently no vaccine licensed to prevent ETEC. Development of prophylaxis against ETEC is challenging due to the vast heterogeneity of the ETEC strains. The discovery of nanobodies has emerged as a successful new biologics in treating mucosal infectious disease as nanobodies can recognize conserved epitopes on hypervariable pathogens. In this study, we performed large screens using immunized llamas and a naive nanobody yeast display library against adhesins of colonization factors. Cross-protective nanobodies were selected with in vitro activities inhibiting mannose-resistant hemagglutination (MRHA) against all eleven major pathogenic ETEC strains. Oral administration of nanobodies led to significant reduction of bacterial colonization in animals challenged with multiple ETEC strains. Structural analysis revealed novel conserved epitopes as critical structural features for pan-ETEC vaccine design. Two of the lead nanobodies, 2R215 and 1D7, were further engineered as trimer or fused with human IgA Fc-fragments as fusionbodies. Oral administration of the trimers or fusionbodies protected mice from infection at a much lower dose compared to the monomeric format. Importantly, fusionbodies prevented infection as a pre-treatment when administrated 2 hours before ETEC challenge to the animals. Together, our study provides the first proof of concept that oral administration of a single nanobody could confer broad protection against major pathogenic ETEC strains. Technological advances in large-scale manufacturing of biological proteins in plants and microorganisms will make nanobody-based immunotherapy a potent and cost-effective prophylaxis or treatment for ETEC.

microbiology↗

bioRxiv2019

Development, characterization and standardization of a nose-only inhalation exposure system for exposure of rabbits to small particle aerosols containing Francisella tularensis.

Inhalation of Francisella tularensis (Ft) causes pneumonic tularemia in humans, a severe disease with a 30-60% mortality rate. Reproducible delivery of aerosolized virulent bacteria in relevant animal models is essential for evaluating medical countermeasures. Here we developed optimized protocols for infecting New Zealand White (NZW) rabbits with aerosols containing Ft. We evaluated relative humidity, aerosol exposure technique, and bacterial culture conditions to optimize spray factor (SF), a central metric of aerosolization. This optimization reduced both inter-and intra-daily variability and were applicable to multiple isolates of Ft. Further improvements in the accuracy and precision of the inhaled pathogen dose were achieved through enhanced correlation of bacterial culture OD and CFU. Plethysmograph data collected during exposures found that respiratory function varied considerably between rabbits, was not a function of weight, and did not improve with acclimation to the system. Vaccine Strain (LVS)-vaccinated rabbits were challenged via aerosol with human-virulent Ft SCHU S4 that had been cultivated in either Mueller Hinton Broth (MHB) or Brain Heart Infusion (BHI) broth. LVS-vaccinated animals challenged with MHB-SCHU S4 experienced short febrile periods (median: 3.2 days), limited weight loss (< 5%), and longer median survival times (~18 d) that were significantly different than unvaccinated controls. In contrast, LVS-vaccinated rabbits challenged with BHI SCHU S4 experienced longer febrile periods (median: 5.5 days), greater weight loss (> 10%), and median survival times that were not significantly different than unvaccinated controls. These studies highlight the importance of careful characterization and optimization of protocols for aerosol challenge with pathogenic agents.

microbiology↗