Cholera toxin B subunit (Istituto Superiore di Sanità)

Chlamydia trachomatis is an obligate intracellular Gram-negative pathogen that causes sexually transmitted infections (STIs) and trachoma. Current interventions are limited due to the widespread nature of asymptomatic infections, and the absence of a licensed vaccine exacerbates the challenge. In this study, we predicted outer membrane β-barrel (OMBB) proteins and designed a multi-epitope vaccine (MEV) construct using identified proteins. We employed a consensus-based computational framework on the C. trachomatis D/UW-3/CX proteome and identified 17 OMBB proteins, including well-known Pmp family members and MOMP. Eight OMBB proteins were computationally characterized, showing significant structural homology with known outer membrane proteins from other bacteria. Sequence-based annotation tools were used to determine their putative functions. B-cell and T-cell epitopes were predicted from the selected proteins. The MEV construct was designed using four cytotoxic T-lymphocyte (CTL) epitopes and 29 helper T-lymphocyte (HTL) epitopes from six OMBB proteins, which were conserved across 106 C. trachomatis serovars. To enhance its immunogenicity, the vaccine was supplemented with the Cholera toxin B subunit and PADRE sequence at the N-terminus. The MEV construct, of length 780 amino acids, was predicted to be antigenic, non-allergenic, non-toxic, and soluble. Secondary structure analysis revealed 95% random coils. A three-dimensional structural model of the MEV was generated and subsequently validated. Molecular docking between MEV and toll-like receptor 4 (TLR4) revealed strong and stable binding interactions. The MEV-TLR4 complex was found to be structurally compact and stable using molecular dynamics simulation. Immune simulation of the MEV construct elicited a strong immune response. This study highlights OMBB proteins as promising immunogenic targets and presents a computationally designed MEV candidate for C. trachomatis infection.

Avian coccidiosis, caused by Eimeria protozoa, presents a significant threat to poultry, with Eimeria tenella being particularly harmful due to its impact on the chicken cecum. Growing resistance to current treatments necessitates alternative therapeutic approaches. Consequently, this study employed an immunoinformatics approach to design a multiepitope vaccine targeting E tenella . Key proteins, including the sporulated oocyst TA4 antigen, alkylglycerone-phosphate synthase, and apical membrane antigen-1, were analysed for epitope prediction. Further comprehensive downstream analysis identified 13 MHC class I, 6 MHC class II, and 7 B-cell epitopes, which were linked with suitable linkers. Also, cholera toxin subunit B was incorporated as an adjuvant, creating a 531-amino-acid construct. The vaccine demonstrated favourable predicted antigenicity, non-allergenicity, and stability properties. Molecular docking predicted interaction with toll-like receptor 15, while immune response simulation showed potential induction of various immunocytes, including helper and cytotoxic T-cells, natural killer cells, and immunoglobulins. The vaccine was predicted to promote antigen clearance after the second dose, suggesting strong memory response potential. These findings indicate the designed vaccine could stimulate a potent protective immune response against E tenella infection. However, further in vitro and in vivo validation studies are necessary to confirm the vaccine’s efficacy before clinical application in poultry immunization programmes.