Comparison and Optimization of Quantification Methods for Shigella flexneri Serotype 6 O-antigen Containing Galacturonic Acid and Methyl-Pentose

Shigella is a leading diarrheal cause of morbidity and mortality worldwide, especially in low- and middle-income countries and in children under five years of age. Increasing levels of antimicrobial resistance make vaccine development an even higher global health priority. S. flexneri serotype 6 is one of the targets of many multicomponent vaccines in development to ensure broad protection against Shigella. The O-antigen (OAg) is a key active ingredient and its content is a critical quality attribute for vaccine release in order to monitor their stability and to ensure appropriate immune response. Here, the optimization of two methods to quantify S. flexneri 6 OAg is reported together with the characterization of their performances. The optimized Dische colorimetric method allows a tenfold increment of the sensitivity with respect to the original method and is useful for fast analysis detecting selectively methyl-pentoses, as rhamnose in S. flexneri 6 OAg. Also, a more specific HPAEC-PAD method was developed, detecting the dimer galacturonic acid-galactosamine (GalA-GalN) coming from S. flexneri 6 OAg acid hydrolysis. These methods will facilitate characterization of S. flexneri 6 OAg based vaccines. The colorimetric method can be used for quantification of other polysaccharide containing methyl-pentoses, and the HPAEC-PAD could be extended to other polysaccharides containing uronic acids.

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Multiomics Characterization of Preterm Birth in Low- and Middle-Income Countries

JAMA Network Open ◽

10.1001/jamanetworkopen.2020.29655 ◽

2020 ◽

Vol 3 (12) ◽

pp. e2029655

Author(s):

Fyezah Jehan ◽

Sunil Sazawal ◽

Abdullah H. Baqui ◽

Muhammad Imran Nisar ◽

Usha Dhingra ◽

...

Keyword(s):

Preterm Birth ◽

Middle Income ◽

Middle Income Countries ◽

Low And Middle Income

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Isolation and characterization of a novel bacteriophage, Kapi1, capable of O-antigen modification in commensal Escherichia coli.

10.1101/2021.04.09.439263 ◽

2021 ◽

Author(s):

Kat Pick ◽

Tracy Lyn Raivio

Keyword(s):

Escherichia Coli ◽

Molecular Mechanisms ◽

Shigella Flexneri ◽

Model System ◽

Temperate Phage ◽

Phage Displays ◽

E Coli ◽

O Antigen ◽

Isolation And Characterization

In this study, we describe the isolation and characterization of novel bacteriophage Kapi1 (vB_EcoP_Kapi1) isolated from a strain of commensal Escherichia coli inhabiting the gastrointestinal tract of healthy mice. We show that Kapi1 is a temperate phage integrated into tRNA argW of strain MP1 and describe its genome annotation and structure. Kapi1 shows limited homology to other characterized prophages but is most similar to the phages of Shigella flexneri, and clusters taxonomically with P22-like phages. Investigation of the lifestyle of Kapi1 shows that this phage displays unstable lysogeny and influences the growth of its host. The receptor for Kapi1 is the lipopolysaccharide O-antigen, and we further show that Kapi1 alters the structure of its hosts O-antigen in multiple ways. We hope to use MP1 and Kapi1 as a model system to explore molecular mechanisms of mammalian colonization by E. coli and ask what the role(s) of prophages in this context might be.

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Isolation and characterization of a novel temperate Escherichia coli bacteriophage, Kapi1, which modifies the O-antigen and contributes to the competitiveness of its host during colonization of the murine gastrointestinal tract.

10.1101/2021.11.03.467220 ◽

2021 ◽

Author(s):

Kat Pick ◽

Tingting Ju ◽

Benjamin P. Willing ◽

Tracy Lyn Raivio

Keyword(s):

Escherichia Coli ◽

Gastrointestinal Tract ◽

Molecular Mechanisms ◽

Shigella Flexneri ◽

Simulated Intestinal Fluid ◽

O Antigen ◽

Isolation And Characterization

In this study, we describe the isolation and characterization of novel bacteriophage vB_EcoP_Kapi1 (Kapi1) isolated from a strain of commensal Escherichia coli inhabiting the gastrointestinal tract of healthy mice. We show that Kapi1 is a temperate phage integrated into tRNA argW of strain MP1 and describe its genome annotation and structure. Kapi1 shows limited homology to other characterized prophages but is most similar to the seroconverting phages of Shigella flexneri, and clusters taxonomically with P22-like phages. The receptor for Kapi1 is the lipopolysaccharide O-antigen, and we further show that Kapi1 alters the structure of its hosts O-antigen in multiple ways. Kapi1 displays unstable lysogeny, and we find that lysogeny is favored during growth in simulated intestinal fluid. Furthermore, Kapi1 lysogens have a competitive advantage over their non-lysogenic counterparts both in vitro and in vivo, suggesting a role for Kapi1 during colonization. We thus report the use of MP1 and Kapi1 as a model system to explore the molecular mechanisms of mammalian colonization by E. coli to ask what the role(s) of prophages in this context might be.

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Contribution of noncanonical antigens to virulence and adaptive immunity in human infection with enterotoxigenic E. coli

10.1101/2020.10.20.348110 ◽

2020 ◽

Author(s):

FM Kuhlmann ◽

RO Laine ◽

S Afrin ◽

R Nakajima ◽

M Akhtar ◽

...

Keyword(s):

Immune Responses ◽

Vaccine Development ◽

Human Infection ◽

Middle Income ◽

Symptomatic Disease ◽

E Coli ◽

Middle Income Countries ◽

Colonization Factor ◽

Specific Antigens ◽

Colonization Factors

AbstractEnterotoxigenic E. coli (ETEC) contribute significantly to the substantial burden of infectious diarrhea among children living in low and middle income countries. In the absence of a vaccine for ETEC, children succumb to acute dehydration as well as non-diarrheal sequelae related to these infections including malnutrition. The considerable diversity of ETEC genomes has complicated canonical vaccine development approaches focused on a subset of antigens known as colonization factors (CFs). To identify additional conserved immunogens, we mined genomic sequences of 89 ETEC isolates, bioinformatically selected potential surface-exposed pathovar-specific antigens conserved in more than 40% of the genomes (n=118), and assembled the representative proteins onto microarrays, complemented with known or putative colonization factor subunit molecules (n=52), and toxin subunits to interrogate samples from individuals with acute symptomatic ETEC infections. Surprisingly, in this open-aperture approach, we found that immune responses were largely constrained to a small number of antigens including individual colonization factor antigens and EtpA, an extracellular adhesin. In a Bangladeshi cohort of naturally infected children < 2 years of age, both EtpA and a second noncanonical antigen, EatA, elicited significant serologic responses that were associated with protection from symptomatic illness. In addition, children infected with ETEC isolates bearing either etpA or eatA genes were significantly more likely to develop symptomatic disease. These studies support a role for more recently discovered noncanonical antigens in virulence and the development of adaptive immune responses during ETEC infections, findings that may inform vaccine design efforts to complement existing approaches.

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Human Mucosal IgA Immune Responses against Enterotoxigenic Escherichia coli

Pathogens ◽

10.3390/pathogens9090714 ◽

2020 ◽

Vol 9 (9) ◽

pp. 714

Author(s):

Saman Riaz ◽

Hans Steinsland ◽

Kurt Hanevik

Keyword(s):

Escherichia Coli ◽

Vaccine Development ◽

Enterotoxigenic Escherichia Coli ◽

Secretory Iga ◽

Small Intestinal Mucosa ◽

Middle Income ◽

Middle Income Countries ◽

Human Volunteers ◽

Iga Response ◽

Small Intestinal

Infection with enterotoxigenic Escherichia coli (ETEC) is a major contributor to diarrheal illness in children in low- and middle-income countries and travelers to these areas. There is an ongoing effort to develop vaccines against ETEC, and the most reliable immune correlate of protection against ETEC is considered to be the small intestinal secretory IgA response that targets ETEC-specific virulence factors. Since isolating IgA from small intestinal mucosa is technically and ethically challenging, requiring the use of invasive medical procedures, several other indirect methods are used as a proxy for gauging the small intestinal IgA responses. In this review, we summarize the literature reporting on anti-ETEC human IgA responses observed in blood, activated lymphocyte assayss, intestinal lavage/duodenal aspirates, and saliva from human volunteers being experimentally infected with ETEC. We describe the IgA response kinetics and responder ratios against classical and noncanonical ETEC antigens in the different sample types and discuss the implications that the results may have on vaccine development and testing.

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Transferable Plasmid-Borne mcr-1 in a Colistin-Resistant Shigella flexneri Isolate

Applied and Environmental Microbiology ◽

10.1128/aem.02655-17 ◽

2018 ◽

Vol 84 (8) ◽

Cited By ~ 4

Author(s):

Beibei Liang ◽

Adam P. Roberts ◽

Xuebin Xu ◽

Chaojie Yang ◽

Xiaoxia Yang ◽

...

Keyword(s):

Shigella Flexneri ◽

Multidrug Resistant ◽

Inverted Repeats ◽

Isolation And Identification ◽

Middle Income ◽

Content Type ◽

Middle Income Countries ◽

Pig Farm ◽

Initial Discovery ◽

Low And Middle Income

ABSTRACT Since the initial discovery of mcr-1 in an Escherichia coli isolate from China, the gene has also been detected in Klebsiella pneumoniae and Salmonella enterica but is rarely reported in other Enterobacteriaceae . Here, we report the isolation and identification of a Shigella flexneri strain harboring mcr-1 from stool samples in a pig farm in China from 2009. The MIC of colistin for the isolate is 4 μg/ml. Conjugation assays showed that the donor S. flexneri strain has functional and transferable colistin resistance. Sequencing revealed that mcr-1 was present on a putative composite transposon flanked by inverted repeats of IS Apl1 . IMPORTANCE There are four species of Shigella , and Shigella flexneri is the most frequently isolated species in low- and middle-income countries (LMICs). In this study, we report a functional, transferable, plasmid-mediated mcr-1 gene in S. flexneri . We have shown that mcr-1 is located on a novel composite transposon which is flanked by inverted repeats of IS Apl1 . The host strain is multidrug resistant, and this multidrug resistance is also transferable. The finding of a functional mcr-1 gene in S. flexneri , a human-associated Enterobacteriaceae family member, is a cause for concern as infections due to S. flexneri are the main Shigella infections in most low- and middle-income countries.

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A framework for Controlled Human Infection Model (CHIM) studies in Malawi: Report of a Wellcome Trust workshop on CHIM in Low Income Countries held in Blantyre, Malawi

Wellcome Open Research ◽

10.12688/wellcomeopenres.12256.1 ◽

2017 ◽

Vol 2 ◽

pp. 70 ◽

Cited By ~ 22

Author(s):

Stephen B Gordon ◽

Jamie Rylance ◽

Amy Luck ◽

Kondwani Jambo ◽

Daniela M Ferreira ◽

...

Keyword(s):

Low Income ◽

Vaccine Development ◽

Clinical Laboratory ◽

Human Infection ◽

Low Income Countries ◽

Infection Model ◽

Proof Of Concept ◽

Middle Income ◽

Regulatory Issues ◽

Middle Income Countries

Controlled human infection model (CHIM) studies have pivotal importance in vaccine development, being useful for proof of concept, pathogenesis, down-selection and immunogenicity studies. To date, however, they have seldom been carried out in low and middle income countries (LMIC), which is where the greatest burden of vaccine preventable illness is found. This workshop discussed the benefits and barriers to CHIM studies in Malawi. Benefits include improved vaccine effectiveness and host country capacity development in clinical, laboratory and governance domains. Barriers include acceptability, safety and regulatory issues. The report suggests a framework by which ethical, laboratory, scientific and governance issues may be addressed by investigators considering or planning CHIM in LMIC.

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Birth Cohort Studies Assessing Norovirus Infection and Immunity in Young Children: A Review

Clinical Infectious Diseases ◽

10.1093/cid/ciy985 ◽

2019 ◽

Vol 69 (2) ◽

pp. 357-365 ◽

Cited By ~ 10

Author(s):

Jennifer L Cannon ◽

Benjamin A Lopman ◽

Daniel C Payne ◽

Jan Vinjé

Keyword(s):

Risk Factors ◽

Young Children ◽

Cohort Studies ◽

Birth Cohort ◽

Diarrheal Disease ◽

Vaccine Development ◽

Natural Infection ◽

Middle Income ◽

Middle Income Countries ◽

Critical Knowledge

Abstract Globally, noroviruses are among the foremost causes of acute diarrheal disease, yet there are many unanswered questions on norovirus immunity, particularly following natural infection in young children during the first 2 years of life when the disease burden is highest. We conducted a literature review on birth cohort studies assessing norovirus infections in children from birth to early childhood. Data on infection, immunity, and risk factors are summarized from 10 community-based birth cohort studies conducted in low- and middle-income countries. Up to 90% of children experienced atleast one norovirus infection and up to 70% experienced norovirus-associated diarrhea, most often affecting children 6 months of age and older. Data from these studies help to fill critical knowledge gaps for vaccine development, yet study design and methodological differences limit comparison between studies, particularly for immunity and risk factors for disease. Considerations for conducting future birth cohort studies on norovirus are discussed.

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Overview of the Development, Impacts, and Challenges of Live-Attenuated Oral Rotavirus Vaccines

Vaccines ◽

10.3390/vaccines8030341 ◽

2020 ◽

Vol 8 (3) ◽

pp. 341 ◽

Cited By ~ 1

Author(s):

Olufemi Samuel Folorunso ◽

Olihile M. Sebolai

Keyword(s):

Low Income ◽

Vaccine Development ◽

Cost Effective ◽

Low Income Countries ◽

Effective Vaccine ◽

Middle Income ◽

Middle Income Countries ◽

Rotavirus Vaccines ◽

The Impact ◽

Infants And Young Children

Safety, efficacy, and cost-effectiveness are paramount to vaccine development. Following the isolation of rotavirus particles in 1969 and its evidence as an aetiology of severe dehydrating diarrhoea in infants and young children worldwide, the quest to find not only an acceptable and reliable but cost-effective vaccine has continued until now. Four live-attenuated oral rotavirus vaccines (LAORoVs) (Rotarix®, RotaTeq®, Rotavac®, and RotaSIIL®) have been developed and licensed to be used against all forms of rotavirus-associated infection. The efficacy of these vaccines is more obvious in the high-income countries (HIC) compared with the low- to middle-income countries (LMICs); however, the impact is far exceeding in the low-income countries (LICs). Despite the rotavirus vaccine efficacy and effectiveness, more than 90 countries (mostly Asia, America, and Europe) are yet to implement any of these vaccines. Implementation of these vaccines has continued to suffer a setback in these countries due to the vaccine cost, policy, discharging of strategic preventive measures, and infrastructures. This review reappraises the impacts and effectiveness of the current live-attenuated oral rotavirus vaccines from many representative countries of the globe. It examines the problems associated with the low efficacy of these vaccines and the way forward. Lastly, forefront efforts put forward to develop initial procedures for oral rotavirus vaccines were examined and re-connected to today vaccines.

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Review on the Recent Advances on Typhoid Vaccine Development and Challenges Ahead

Clinical Infectious Diseases ◽

10.1093/cid/ciaa504 ◽

2020 ◽

Vol 71 (Supplement_2) ◽

pp. S141-S150

Author(s):

Khalid Ali Syed ◽

Tarun Saluja ◽

Heeyoun Cho ◽

Amber Hsiao ◽

Hanif Shaikh ◽

...

Keyword(s):

Typhoid Fever ◽

Low Income ◽

Vaccine Development ◽

Middle Income ◽

Middle Income Countries ◽

Sanitation And Hygiene ◽

Contaminated Food ◽

Improved Sanitation ◽

Typhoid Vaccines ◽

And Control

Abstract Control of Salmonella enterica serovar typhi (S. typhi), the agent of typhoid fever, continues to be a challenge in many low- and middle-income countries. The major transmission route of S. typhi is fecal-oral, through contaminated food and water; thus, the ultimate measures for typhoid fever prevention and control include the provision of safe water, improved sanitation, and hygiene. Considering the increasing evidence of the global burden of typhoid, particularly among young children, and the long-term horizon for sustained, effective water and sanitation improvements in low-income settings, a growing consensus is to emphasize preventive vaccination. This review provides an overview of the licensed typhoid vaccines and vaccine candidates under development, and the challenges ahead for introduction.

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