In silico designing of vaccine candidate against Clostridium difficile

Srijita Basak,Pratap D Bade,Debashrito Deb,Utkarsh Narsaria,Tamalika Kar,Anurag P Srivastava,Filippo Castiglione,Indraneel Sanyal

doi:10.1038/s41598-021-93305-6

Srijita Basak, Pratap D Bade + Show 6 more

Open Access

https://doi.org/10.1038/s41598-021-93305-6

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Abstract

Clostridium difficile is a spore-forming gram-positive bacterium, recognized as the primary cause of antibiotic-associated nosocomial diarrhoea. Clostridium difficile infection (CDI) has emerged as a major health-associated infection with increased incidence and hospitalization over the years with high mortality rates. Contamination and infection occur after ingestion of vegetative spores, which germinate in the gastro-intestinal tract. The surface layer protein and flagellar proteins are responsible for the bacterial colonization while the spore coat protein, is associated with spore colonization. Both these factors are the main concern of the recurrence of CDI in hospitalized patients. In this study, the CotE, SlpA and FliC proteins are chosen to form a multivalent, multi-epitopic, chimeric vaccine candidate using the immunoinformatics approach. The overall reliability of the candidate vaccine was validated in silico and the molecular dynamics simulation verified the stability of the vaccine designed. Docking studies showed stable vaccine interactions with Toll‐Like Receptors of innate immune cells and MHC receptors. In silico codon optimization of the vaccine and its insertion in the cloning vector indicates a competent expression of the modelled vaccine in E. coli expression system. An in silico immune simulation system evaluated the effectiveness of the candidate vaccine to trigger a protective immune response.

Highlights

Clostridium difficile is a spore-forming gram-positive bacterium, recognized as the primary cause of antibiotic-associated nosocomial diarrhoea
A significant role is played by the cytotoxic T lymphocytes (CTL) and helper T lymphocytes (HTL) in generation of a long-lasting adaptive immunity against various microbial infections
HTL epitopes are essential for the development of memory helper T cells which are pivotal to both the activation of cytotoxic T cells and stimulation of B lymphocytes responsible for producing antibodies[42]

Summary

Introduction

Clostridium difficile is a spore-forming gram-positive bacterium, recognized as the primary cause of antibiotic-associated nosocomial diarrhoea. The surface layer protein and flagellar proteins are responsible for the bacterial colonization while the spore coat protein, is associated with spore colonization Both these factors are the main concern of the recurrence of CDI in hospitalized patients. CDI contamination occurs after the ingestion of spores, which are shed into the environment by patients with or without disease symptoms These spores germinate in the gastro-intestinal tract, allowing the colonization of the vegetative cells in the gut and multiplication in the colon[12]. Protein in the S-layer, acts as a major colonization factor[19] and recombinant vaccines developed against SlpA showed reduced gut colonization in m ice[7,20] This protein can be regarded as a possible candidate for the design of vaccines

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