Cloning, expression, and purification of Brucella suis outer membrane proteins

The design of multiepitope vaccines from plasmids of diarrheagenic Escherichia coli against diarrhoea infection: Immunoinformatics approach

Diarrhoea infection is a major global health public problem and is caused by many organisms including diarrheagenic Escherichia coli pathotypes. The common problem with diarrhoea is the drug resistance of pathogenic bacteria, the most promising alternative means of preventing drug resistance is vaccination. However, there has not been any significant success in the prevention of diarrhoea caused by E. coli through vaccination. Epitope-based vaccine is gaining more attention due to its safety and specificity. Sequence variation of protective antigens of the pathogen has posed a new challenge in the development of epitope-based vaccines against the infection, leading to the necessity of multiepitope based design. In this study, immunoinformatics tools were used to design multiepitope vaccine candidates from plasmid genome sequences of multiple pathotypes of E. coli species involved in diarrhoea infections. The ability of the identified epitopes to be used as a cross-protect multiepitope vaccine was achieved by identifying conserved, immunogenic and antigenic peptides that can elicit CD4⁺ T-cell, CD8⁺ T-cell and B-cell and bind to MHC I and II HLA alleles. The molecular docking results of T-cell epitopes showed their well binding affinity to receptive protein and with a wider population coverage. The different multiepitope-based vaccines (MEVCs) candidates were constructed and based on the types of epitope linker they contained. The MEVCs exhibited very good binding interactions with the human immune receptor. Among multiepitope vaccines constructed, MEVC6, MEVCA and MEVCB are more promising as potential vaccine candidates for cross-protection against gastrointestinal infections according to the computational study. It is also hoped that after validation and testing, the predicted multiepitope-based vaccine candidates will probably resolve the challenge of immunological heterogeneity facing enteric vaccine development.

Diagnostic potential of Brucella melitensis Rev1 native Omp28 precursor in human brucellosis

Serologic tests for brucellosis aim to detect antibodies produced against membranous lipopolysaccharide of bacteria. Diagnostic use of this method is limited due to false positiveness. This study evaluates an alternative antigen to lipopolysaccharides (LPS), outer membrane 28-precursor-protein, of Brucella melitensis Rev1 for its diagnostic value. Omp28 precursor of B. melitensis Rev1 was cloned, expressed, and purified. 6-His and sumo epitope tags were used to tag the protein at N-termini. Omp28 gene was amplified based on the ORF sequence and cloned into a pETSUMO vector. The recombinant construct was propagated in Escherichia coli One Shot^® Mach1™ cells then transformed into E. coli BL21(D3) cells for protein expression. The purified protein was studied in an indirect ELISA for diagnosis of brucellosis. Sera samples from 60 patients were screened by ELISA and the results were compared to Rose Bengal plate test. Recombinant antigen-based iELISA has given a successful outcome with the sensitivity, specificity, positive predictive value, and negative predictive value of 87.8%, 96.2%, 96.6%, and 78.78%, respectively. In conclusion, recombinant production and purification of the immunodominant Omp28 precursor protein has been achieved successfully in a one-step process with efficient yield and can be used for diagnosis of brucellosis in humans.

Impact of DNA damaging agents on genome-wide transcriptional profiles in two marine Synechococcus species

Marine microorganisms, particularly those residing in coastal areas, may come in contact with any number of chemicals of environmental or xenobiotic origin. The sensitivity and response of marine cyanobacteria to such chemicals is, at present, poorly understood. We have looked at the transcriptional response of well characterized Synechococcus open ocean (WH8102) and coastal (CC9311) isolates to two DNA damaging agents, mitomycin C and ethidium bromide, using whole-genome expression microarrays. The coastal strain showed differential regulation of a larger proportion of its genome following “shock” treatment with each agent. Many of the orthologous genes in these strains, including those encoding sensor kinases, showed different transcriptional responses, with the CC9311 genes more likely to show significant changes in both treatments. While the overall response of each strain was considerably different, there were distinct transcriptional responses common to both strains observed for each DNA damaging agent, linked to the mode of action of each chemical. In both CC9311 and WH8102 there was evidence of SOS response induction under mitomycin C treatment, with genes recA, lexA and umuC significantly upregulated in this experiment but not under ethidium bromide treatment. Conversely, ethidium bromide treatment tended to result in upregulation of the DNA-directed RNA polymerase genes, not observed following mitomycin C treatment. Interestingly, a large number of genes residing on putative genomic island regions of each genome also showed significant upregulation under one or both chemical treatments.

Molecular cloning of virB12 gene of Brucella melitensis 16M strain in pET28a vector

OBJECTIVE

To clone the virB12 gene in pET28a expression vector for production of recombinant protein to be used as antigenic component for future serological test development.

METHODS

Brucella melitensis (B. melitensis) 16M strain was cultured and bacterial DNA was extracted by Bioneer AccuPrep® Genomic DNA Extraction Kit. Oligonucleotide primer pair was designed based on Brucella virB12 gene sequence with BamHI and HindIII restriction site at 5' end of the forward and reverse primers, respectively. DNA amplification was performed using PrimSTAR® HS DNA polymerase and the PCR product was purified by DNA AccuPrep®Gel Purification Kit. Purified DNA was cloned into pJET1.2 cloning vector. VirB12 gene fragment was excised from pJET1.2 using BamHI/HindIII and subsequently subcloned into pET28a (+).

RESULTS

Brucella virB12 gene was successfully cloned in pJET1.2 and then in pET28a (+) plasmids. PCR and restriction enzyme digestion confirms the procedure.

CONCLUSION

We cloned and expressed the Brucella virB12 gene which could be used as antigenic component for specific serological assay development.

The antibody against a nuclear autoantigenic sperm protein can result in reproductive failure

To study whether the antibody against the testis form of the nuclear autoantigenic sperm protein (tNASP) could result in reproductive failure, we successfully cloned and expressed a 339-bp cDNA fragment of mouse tNASP (mtNASP). Using mouse as a model, recombinant mtNASP (rmtNASP) and a synthetic peptide, human tNASP(393-408) (htNASP(393-408)), were investigated for their antifertility effect. Active immunization with rmtNASP or the synthesized peptide raised high antibody titers in the immunized mice. Sperm-egg binding and fusion assay were carried out in 8-10-week-old BALB/c mice. Sperm-egg binding and in vitro fertilization of mouse oocytes were inhibited by co-incubation of zona-free mouse oocytes with capacitated mouse spermatozoa in the presence of varying concentrations of the antisera against rmtNASP. There was a significant antifertility effect in animals immunized with rmtNASP or the synthesized peptide. The effect on fertility in the mice immunized with the synthesized peptide was reversible. Our data indicate that active immunization with rmtNASP antigen may induce a strong antibody response that causes an inhibition of fertility.

Characterization of OmpK, GAPDH and their fusion OmpK-GAPDH derived from Vibrio harveyi outer membrane proteins: their immunoprotective ability against vibriosis in large yellow croaker (Pseudosciaena crocea)

AIM

To investigate the immunoprotection of three recombinant proteins derived from the Vibrio harveyi outer membrane proteins (OMPs) OmpK, glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and their fusion OmpK-GAPDH as vaccine candidates from vibriosis of large yellow croaker (Pseudosciaena crocea).

METHODS

The ompK gene, of which the leader sequence was omitted, was fused with the gapdh gene. Three recombinant proteins r-OmpK, r-GAPDH and r-OmpK-GAPDH were expressed and purified. Western blots were carried out to detect the specificity of the antibodies raised against the recombinant proteins; Fish were immunized with recombinant proteins and challenged by native V. harveyi. The immunoresponse to the recombinant proteins were determined by ELISA and phagocytic activity assay.

CONCLUSIONS

The fusion protein r-OmpK-GAPDH can afford greater protection against the wild V. harveyi than r-OmpK or r-GAPDH alone or their mixture in humoral and cellular immunity, indicating that OmpK and GAPDH could produce a synergistic immunoprotection against vibriosis of large yellow croaker (Pseudosciaena crocea) when fused into OmpK-GAPDH with a linker.

SIGNIFICANCE AND IMPACT OF THE STUDY

It has been realized that a multi-component OMP antigen can induce a higher frequency of immune effectors than a single OMP. The results presented here bring forth a good suggestion for the subunit vaccine design based on the OMPs of gram-negative pathogens.