Search

The emergence of drug-resistant Acinetobacter baumannii is the global health problem associated with high mortality and morbidity. Therefore it is high time to find a suitable therapeutics for this pathogen. In the present study, subtractive proteomics along with reverse vaccinology approaches were used to predict suitable therapeutics against A. baumannii. Using subtractive proteomics, we have identified promiscuous antigenic membrane proteins that contain the virulence factors, resistance factors and essentiality factor for this pathogenic bacteria. Selected promiscuous targeted membrane proteins were used for the design of chimeric-subunit vaccine with the help of reverse vaccinology. Available best tools and servers were used for the identification of MHC class I, II and B cell epitopes. All selected epitopes were further shortlisted computationally to know their immunogenicity, antigenicity, allergenicity, conservancy and toxicity potentials. Immunogenic predicted promiscuous peptides used for the development of chimeric subunit vaccine with immune-modulating adjuvants, linkers, and PADRE (Pan HLA-DR epitopes) amino acid sequence. Designed vaccine construct V4 also interact with the MHC, and TLR4/MD2 complex as confirm by docking and molecular dynamics simulation studies. Therefore designed vaccine construct V4 can be developed to control the host-pathogen interaction or infection caused by A. baumannii.

Objective: To develop a safe and effective oral vaccine against Helicobacter pylori using its HpaA protein expressed in Lactococcus lactis., Results: The gene encoding HpaA was obtained by PCR and ligated to pNZ8110-lysM following digestion with NaeI + SphI. The recombinant plasmid was transferred into E. coli for multiplication, and then into L. lactis. The recombinant L. lactis was induced to express HpaA, resulting in two products of 29 and 25 kDa, both of which yielded positive immunoreaction with mouse antisera against H. pylori, as confirmed by immunoblot assays. The 29 kDa product constituted 12% of the cell lysates. Oral inoculation with the engineered L. lactis evoked significantly elevated serum IgG level in mice (P < 0.05)., Conclusions: A novel engineered L. lactis strain was developed that efficiently produces whole HpaA protein with desired antigenicity and potent immunogenicity. It provides a basis for approaches to L. lactis-delivered anti-H. pylori vaccination.

Chloroplast transformation technology is a promising approach for the production of foreign proteins in plants with expression levels of up to 70 % of total soluble protein (TSP) achieved in tobacco. However, expression of foreign protein in the chloroplast can lead to drastic or even lethal effects in transplastomic plants grown in soil, thereby potentially limiting the applicability of this technology. For instance, previous attempts to express the outer surface protein A (OspA) from Borrelia burgdorferi in tobacco chloroplasts led to plant death when expressed at 10 % TSP. We show here that this earlier transplastomic line, as well as a new plant line, OspA:YFP, expressing OspA fused to the yellow fluorescent protein, can be propagated in temporary immersion bioreactors (TIBs) using AlkaBurst™ technology to produce leafy biomass that expressed OspA at levels of up to 7.6 % TSP, to give a maximum yield of OspA of about 108 mg/L. Our results show that TIBs provide an alternative method for the production of transplastomic biomass expressing proteins toxic for plants and is a particularly useful approach when 'absolute' containment is required.

Dendritic cells (DCs) are key regulators of adaptive T-cell responses. By capturing exogenous antigens and presenting antigen-derived peptides via major histocompatibility complex molecules to naïve T cells, DCs induce antigen-specific immune responses in vivo. In order to induce effective host immune responses, active delivery of exogenous antigens to DCs is considered important for future vaccine development. We recently generated bionanocapsules (BNCs) consisting of hepatitis B virus surface antigens that mediate stringent in vivo cell targeting and efficient endosomal escape, and after the fusion with liposomes (LP) containing therapeutic materials, the BNC-LP complexes deliver them to human liver-derived tissues in vivo. BNCs were further modified to present the immunoglobulin G (IgG) Fc-interacting domain (Z domain) derived from Staphylococcus aureus protein A in tandem. When mixed with IgGs, modified BNCs (ZZ-BNCs) displayed the IgG Fv regions outwardly for efficient binding to antigens in an oriented-immobilization manner. Due to the affinity of the displayed IgGs, the IgG-ZZ-BNC complexes accumulated in specific cells and tissues in vitro and in vivo. After mixing ZZ-BNCs with antibodies against DCs, we used immunocytochemistry to examine which antibodies delivered ZZ-BNCs to mouse splenic DCs following intravenous injection of the ZZ-BNCs. ZZ-BNCs displaying anti-CD11c monoclonal antibodies (α-CD11c-ZZ-BNCs) were found to accumulate with approximately 62% of splenic DCs, and reside within some of them. After the fusion with liposomes containing antigens, the α-CD11c-ZZ-BNCs could elicit the respective antibodies more efficiently than other nontargeting control vaccines, suggesting that this DC-specific nanocarrier is promising for future vaccines.

The gram-negative anaerobic oral bacterium Porphyromonas gingivalis initiates periodontal disease through fimbrial attachment to saliva-coated oral surfaces. To study the effects of immunomodulation on enhancement of subunit vaccination, the expression in E. coli and immunogenicity of P. gingivalis fimbrial protein (FimA) linked to the C-terminus of the cholera toxin B subunit (CTB) were investigated. Complementary DNAs encoding the P. gingivalis 381 fimbrillin protein sequence FimA1 (amino acid residues 1-200) and FimA2 (amino acid residues 201-337) were cloned into an E. coli expression vector downstream of a cDNA fragment encoding the immunostimulatory CTB. CTB-FimA1 and CTB-FimA2 fusion proteins synthesized in E. coli BL21 (DE3) cells were purified under denaturing conditions by Ni2+-NTA affinity column chromatography. Renaturation of the CTB-FimA1 and CTB-FimA2 fusion proteins, permitted identification of CTB-FimA pentamers and restored CTB binding activity to GM1-ganglioside to provide a biologically active CTB-FimA fusion protein. Mice orally inoculated with purified CTB-FimA1 or CTB-FimA2 fusion proteins generated measurable FimA1 and FimA2 IgG antibody titers, while no serum fimbrial IgG antibodies were detected when mice were inoculated with FimA1 or FimA2 proteins alone. Immunoblot analysis confirmed that sera from mice immunized with CTB linked to FimA1 or FimA2 contained antibodies specific for P. gingivalis fimbrial proteins. In addition, mice immunized with FimA2 or CTB-FimA2 generated measurable intestinal IgA titers indicating the presence of fimbrial antibody class switching. Further, mice orally immunized with CTB-FimA1 generated higher IgA antibody titers than mice inoculated with FimA1 alone. The experimental data show that the immunostimulatory molecule CTB enhances B cell-mediated immunity against linked P. gingivalis FimA fusion proteins, in comparison to immunization with FimA protein alone. Thus, linkage of CTB to P. gingivalis fimbrial antigens can increase subunit vaccine immunogenicity to provide enhanced protection against periodontal disease.

Objective: To construct a prokaryotic expression system to serially express Alloferon-1 and to determine the anti-tumor activity of its products in vitro., Methods: An artificial fusion gene containing 6 x His-EK-8 x Alloferon-1-EK-6 x His sequences was constructed by linking primer PCR. By using routine molecular biological methods, the artificial fusion gene was cloned and its prokaryotic expression system was then constructed. SDS-PAGE and BioRad Agarose Image Analysor was applied to measure the expression and output of the target recombinant products 8 x rAlloferon-1-EK. Ni-NTA affinity chromatography and EK digestion and Sephadex G-50 chromatography were performed to extract 8 x rAlloferon-1-EK and rAlloferon-1-EK, respectively. The proliferation of KB, SGC and HL-60 tumor cells was tested by using MTT method after treatment with directly synthesized Alloferon-1 (sAlloferon-1), Aloferon-1-EK (sAlloferon-1-EK) and rAlloferon-1-EK., Result: The target artificial fusion gene and its prokaryotic expression system pET42a-8 x rAlloferon-1-EK-E. coliBLDE3 with the expected sequences were obtained. Under inducement of IPTG, the prokaryotic expression system expressed the target serial recombinant protein 8 x rAlloferon-1-EK and its output was approximate 30 % of the total bacterial proteins. 8 x rAlloferon-1-EK and rAlloferon-1-EK were obtained through Ni-NTA and Sephadex G-50 columns. sAlloferon-1, sAlloferon-1-EK and rAlloferon-1ìrAlloferon-EK showed similar remarkable effects of inhibiting the growth and proliferation of KB, SGC and HL-60 cells in vitro within 25 approximately 100 microg/ml concentration range (P<0.01), and there were no significant differences in the inhibiting effects among the three agents (P>0.05)., Conclusion: A prokaryotic expression system to serially express rAlloferon-1 has been successfully constructed. The product rAlloferon-1-EK has a similar anti-tumor activity compared to both the synthesized Alloferon-1 and Alloferon-1-EK in vitro.