Vaccine Research
Volume:10 Issue: 1, Winter and Spring 2023

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has spread worldwide as an Omicron variant (B.1.1.529). Compared with the original SARS-CoV-2, this variant has more than 30 mutations on its spike. The Lambda variant (known as SARS-CoV-2 lineage C.37) is another variant of interest. The Lambda spike protein bears seven mutations; G75V, T76I, L452Q, F490S, D614G, T859N, and ∆247-253. The effect of such mutations on immune escape from neutralizing antibodies and infectivity is unknown.

In-silico tools were applied to predict the antigenicity of the spikes of Lambda and Omicron variants and the results were compared to the reference Wuhan spike protein antigenicity. SWISS-MODEL, MolProbity, and QMEAN were used for model quality assessment. DiscoTope2.0, BEpro, and Ellipro were used for the prediction of conformational and linear B cell epitopes.

The evaluation of the obtained modeled proteins showed that the predicted models by Swiss-Model had higher quality for Lambda and Omicron spikes with 0.56% and 1.63% of residues in outlier and 94.39% and 92.51% residues in favored regions, respectively. The results of conformational B cell epitope prediction showed 6 epitopic regions on S1 of Lambda spike and 1 epitopic region on the S2 segment of the protein. For the Omicron variant, 9 epitopic regions existed on S1 and 1 epitopic region (1137-1159) was on S2.

Our results suggested that B cell epitope removal and reducing the antigenicity properties of the epitopic residues involve reducing susceptibility to antibody neutralization of the mutant protein

The SARS-CoV-2 epidemic has infected and killed millions of people worldwide since 2019. Therapies available for SARS-CoV-2 disease are limited due to the sudden emergence of the virus. The need for appropriate vaccines to combat this dangerous virus is essential. Induction of specific antibodies against SARS-CoV-2 virus is mainly by nucleocapsid (N), membrane (M) and spike glycoprotein (S) proteins. On the other hand, cost-effective and fast methods for the expression and purification of recombinant proteins that retain antigenic properties are essential for vaccine development.

A DNA fragment encoding the N, M and S1 proteins was inserted into pET28a vector to make an expression plasmid. The recombinant protein was then expressed in Escherichia coli Rosetta strain and purified by Ni-NTA column, followed by confirmation by SDS-PAGE and Western blotting.

PCR results showed that the gene was inserted correctly into the expression vector. The expression of the recombinant protein containing N, M and S1 proteins from SARS CoV-2 was optimized in a bacterial system. The recombinant protein was successfully purified from Ni-NTA column with a high yield

Upon further evaluations, this cost-effective approach for the production of recombinant antigenic proteins in E. coli (Rosetta), could potentially be used for the development of vaccines against coronaviruses infections.

There is currently no approved vaccine available for Acinetobacter baumannii, an important agent of nosocomial infections. Recently, Omp22 from A. baumannii has been identified as a vaccine candidate that stimulates effective immune responses in mice. However, limited data is available about this protein. This study aimed to comprehensively analyze the immunoinformatic properties of Omp22 and its expression in vitro.

The protein sequence of Omp22 was scanned for subcellular localization, antigenicity, allergenicity, homology to human proteome, physiochemical characteristics, linear and conformational B-cell epitopes, MHC binding sites, tertiary structure prediction, and molecular dockings. Additionally, the gene encoding omp22 was cloned into the pET-28a (+) vector and the expression level was optimized.

Omp22 (22.48 kDa, pI of 9.30) belongs to the outer membrane proteins superfamily without transmembrane helices. Omp22 was predicted to be a non-allergenic antigen with appropriate stability. Two linear B-cell epitopes were identified, as well as 108 MHC-I and 50 MHC-II binding sites. Three conformational B-cell epitopes were identified through 3D structure prediction, and molecular docking analysis showed desirable interactions in the docked complexes. The optimized expression of the recombinant Omp22 was successfully achieved.

This study represents a significant step towards developing an Omp22-based vaccine candidate against A. baumannii. However, further experimental analyses are still needed

Uropathogenic Escherichia coli (UPEC) is the main cause of urinary tract infections (UTIs). Increasing antibiotic resistance among UPEC isolates complicate UTI treatment in the future. Finding alternative approaches against UPECs seems necessary. Despite many efforts to develop a vaccine for UPEC, there is no yet effective vaccine against the bacteria.

Designing a multi-epitope vaccine based on the main UPEC virulence factors can be an effective strategy for prevention of UTI. In the previous study, three important proteins from UPEC strains including FimH, FyuA and CNF-1 were selected to design a multi-epitope antigen which was used for production of polyclonal antibody in rabbits. In the present study, the collected sera were used for evaluating the sensitivity, specificity, cell adherence, and biofilm inhibition of the developed polyclonal antibody.

ELISA results showed high binding activity of the rabbit polyclonal antibody against the multi-epitope protein even in low antibody titers. In addition, the polyclonal antibody showed antigenic specificity against the multi-epitope protein and UPEC UTI89 strain. Cross-reactivity of the polyclonal antibody was observed with Klebsiella pneumonia. Bacterial adhesion was reduced significantly in the presence of antibody, compared to the controls.

The generated polyclonal antibody significantly reduced in vitro biofilm formation of UTI89 strain while did not significantly affect the biofilm degradation. These results highlight the potential of the designed multi-epitope protein as a promising vaccine candidate for the prevention of UTI caused by UPEC.

The most widespread gastrointestinal infection globally is attributed to non-typhoidal Salmonella (NTS). Given the rising prevalence of antibiotic-resistant strains and the absence of commercially available vaccines, there is a crucial need for research and development of new vaccines against NTS. The purpose of the present study was to design a multi-epitope vaccine targeting non-typhoidal salmonella serovars (Salmonella typhimurium and Salmonella enteritidis) based on fimbriae protein using an immunoinformatics approach.

The sequences of the fimbriae protein were obtained and the predicted epitopes for B and T lymphocytes were identified. The epitopes' antigenic features, non-allergenicity, and non-toxicity were investigated, and the vaccine model was constructed. The characteristics of the vaccine were determined, and its effectiveness was evaluated through docking, molecular dynamics simulation involving the interaction between the vaccine and immune receptors, and immunological simulation. The vaccine was then optimized for cloning.

B and T lymphocyte-targeting vaccine construct was developed by selecting twelve epitopes. Immunoinformatics analyses predicted that the constructed vaccine is reliable and safe, hydrophilic, and exhibits stability under diverse temperatures and conditions. Additionally, it displayed the capability to bind to immune receptors TLR4, HLA-C, and HLA-DRB1. Moreover, this vaccine candidate stimulates antibody response and memory B and T cell activation after repeated injection.

This study introduced the primary results of a novel multi-epitope vaccine against NTS based on adhesion protein.  In-silico methods predicted that the proposed vaccine can potentially elicit an immune response and be expressed in the prokaryotic system

Rotaviruses (RV) and hepatitis A virus (HAV) are pathogens responsible for more than 2 million hospitalizations, especially in developing countries, due to transmission through the fecal-oral route. Currently, there are several FDA-approved RV and HAV vaccines available which are based on killed or attenuated viruses. However, these vaccines often have side effects and low efficacy in eliciting specific immunity. Therefore, the design of a vaccine based on a recombinant protein, composed of RV and HAV antigens seems essential.

We used bioinformatics tools to design and analyze the properties, predict the structure and evaluate the function, immunogenicity, antigenicity, and truncated sequences of HAV VP1 and RV VP8 as a dual vaccine platform. The predicted epitopes were expressed as a recombinant protein in Escherichia coli BL21 where half of the VP1 protein was fused with the Rota protein VP8 using  pET24a expression vector,.

The expressed protein was confirmed by SDS-PAGE and Western blotting. Subsequently, high-scale expression, purification, refolding and determination of the protein concentration (~2.4 µg/µl) were obtained.

Upon completion of the future immunogenicity evaluation through injection into mice, the present fusion protein can potentially serve as a candidate for a recombinant vaccine against both RV and HAV infections.