Immunization with recombinant protein Ag43::UpaH with alum and 1,25(OH)2D3 adjuvants significantly protects Balb/C mice against urinary tract infection caused by uropathogenic Escherichia coli

The majority of urinary tract infections (UTIs) are caused by uropathogenic Escherichia coli (UPEC). Designing a vaccine will certainly reduce the occurrence of infection and antibiotic resistance of the isolates. Antigen 43 (Ag43) and autotransporter H (UpaH) have been associated with the virulence of UPEC. In the present study, the efficacy of different formulations of a hybrid protein composed of Ag43 and UpaH with and without alum and 1,25(OH)2D3 (Vitamin D3) adjuvants were evaluated in mice model. A significant increase in IgG and cellular responses was developed against Ag43::UpaH as compared to the control mice. The addition of alum or a mixture of alum and Vitamin D3 to the protein significantly enhanced the serum IgG responses and tended to remain in a steady state until 6 months. In addition, the mentioned formulations produced significant amounts of IgG1, IL-4, and IL-17 as compared to the fusion protein alone. In addition to the mentioned formulations, the combination of protein with Vitamin D3 also resulted in significantly higher serum IgA and IFN-γ levels as compared to the fusion protein alone. Mice immunized with fusion plus alum and formulation protein admixed with both alum and Vitamin D3 significantly reduced the bacterial load in the bladders and kidneys of mice as compared to the control. In this study, for the first time, the ability of a novel hybrid protein in combination with adjuvants alum and Vitamin D3 was evaluated against UPEC. Our results indicated that fusion Ag43::UpaH admixed with alum and Vitamin D3 could be a promising candidate against UTIs.

Early detection of viable Francisella tularensis in environmental matrices by culture-based PCR

BACKGROUND

Francisella tularensis is a fastidious, Gram-negative coccobacillus and is the causative agent of tularemia. To assess viability yet overcome lengthy incubation periods, a culture-based PCR method was used to detect early growth of the lowest possible number of F. tularensis cells. This method utilized a previously developed enhanced F. tularensis growth medium and is based on the change in PCR cycle threshold at the start and end of each incubation.

RESULTS

To test method robustness, a virulent Type A1 (Schu4) and B (IN99) strain and the avirulent Live Vaccine Strain (LVS) were incubated with inactivated target cells, humic acid, drinking and well water, and test dust at targeted starting concentrations of 1, 10, and 100 CFU mL- 1 (low, mid, and high, respectively). After 48 h, LVS growth was detected at all targeted concentrations in the presence of 106 inactivated LVS cells; while Schu4 and IN99 growth was detected in the presence of 104 Schu4 or IN99 inactivated cells at the mid and high targets. Early detection of F. tularensis growth was strain and concentration dependent in the presence of fast-growing well water and test dust organisms. In contrast, growth was detected at each targeted concentration by 24 h in humic acid and drinking water for all strains.

CONCLUSIONS

Results indicated that the culture-based PCR assay is quick, sensitive, and specific while still utilizing growth as a measure of pathogen viability. This method can circumvent lengthy incubations required for Francisella identification, especially when swift answers are needed during epidemiological investigations, remediation efforts, and decontamination verification.

Development of a multiple-antigen protein fusion vaccine candidate that confers protection against Bacillus anthracis and Yersinia pestis

Bacillus anthracis and Yersinia pestis are zoonotic bacteria capable of causing severe and sometimes fatal infections in animals and humans. Although considered as diseases of antiquity in industrialized countries due to animal and public health improvements, they remain endemic in vast regions of the world disproportionally affecting the poor. These pathogens also remain a serious threat if deployed in biological warfare. A single vaccine capable of stimulating rapid protection against both pathogens would be an extremely advantageous public health tool. We produced multiple-antigen fusion proteins (MaF1 and MaF2) containing protective regions from B. anthracis protective antigen (PA) and lethal factor (LF), and from Y. pestis V antigen (LcrV) and fraction 1 (F1) capsule. The MaF2 sequence was also expressed from a plasmid construct (pDNA-MaF2). Immunogenicity and protective efficacy were investigated in mice following homologous and heterologous prime-boost immunization. Antibody responses were determined by ELISA and anthrax toxin neutralization assay. Vaccine efficacy was determined against lethal challenge with either anthrax toxin or Y. pestis. Both constructs elicited LcrV and LF-specific serum IgG, and MaF2 elicited toxin-neutralizing antibodies. Immunizations with MaF2 conferred 100% and 88% protection against Y. pestis and anthrax toxin, respectively. In contrast, pDNA-MaF2 conferred only 63% protection against Y. pestis and no protection against anthrax toxin challenge. pDNA-MaF2-prime MaF2-boost induced 75% protection against Y. pestis and 25% protection against anthrax toxin. Protection was increased by the molecular adjuvant CARDif. In conclusion, MaF2 is a promising multi-antigen vaccine candidate against anthrax and plague that warrants further investigation.

Anthrax and plague are ancient infectious diseases that continue to affect people living in poor, endemic regions and to threaten industrialized nations due to their potential use in biowarfare. Candidate vaccines need improvement to minimize non-desirable effects and increase their efficacy. The purpose of this work was to develop and evaluate a single subunit vaccine capable of conferring protection against Bacillus anthracis and Yersinia pestis. To this end, specific regions from their genome or key protective protein sequences from both microorganisms were combined to obtain either recombinant plasmids or recombinant proteins and tested as vaccine candidates in mice. The recombinant protein MaF2 induced specific antibody responses and afforded full and partial protection against Y. pestis and B. anthracis, respectively. Meanwhile, the DNA vaccine equivalent to MaF2 conferred only partial protection against Y. pestis, which increased when combined with an MaF2 protein boost. MaF2 emerged as a promising dual pathogen recombinant vaccine that warrants further investigation.

Reverse vaccinology and subtractive genomics-based putative vaccine targets identification for Burkholderia pseudomallei Bp1651

The Burkholderia pseudomallei is a unique bio-threat and causative agent of melioidosis. The B. pseudomallei Bp1651 strain has been isolated from a chronic cystic fibrosis patient. The genome-level DNA sequences information of this strain has recently been published. Unfortunately, there is no commercial vaccine available till date to combat B. pseudomallei infection. The genome-wide prioritization approaches are widely used for the identification of potential therapeutic candidates against pathogens. In the present study, we utilized the recently available annotated genomic information of B. pseudomallei Bp1651 through subtractive genomics and reverse-vaccinology strategies to identify its potential vaccine targets. The analyses identified more than 60 pathogen-specific, human host non-homologous proteins that may prioritize in future studies to investigate therapeutic targets for B. pseudomallei Bp1651. The potential B and T-cells antigenic determinant peptides from these pathogen-specific proteins were cataloged using antigenicity and epitope prediction tools. The analyses unveiled a promising antigenic peptide "FQWEFSLSV" from protein-export membrane protein (SecF) of Bp1651 strain, which was predicted to interact with multiple class I and class II MHC alleles with IC₅₀ value < 100 nM. The molecular docking analysis verified favorable molecular interaction of this lead antigenic peptide with the ligand-binding pocket residues of HLA A*02:06 human host immune cell surface receptor. This peptide is predicted to be a suitable epitope capable to elicit the cell-mediated immune response against the B. pseudomallei pathogen. The putative epitopes and proteins identified in this study may be promising vaccine targets against Bp1651 as well as other pathogenic strains of B. pseudomallei.

Pathway based therapeutic targets identification and development of an interactive database CampyNIBase of Campylobacter jejuni RM1221 through non-redundant protein dataset

The bacterial species Campylobacter jejuni RM1221 (CjR) is the primary cause of campylobacteriosis which poses a global threat for human health. Over the years the efficacy of antibiotic treatment is becoming more fruitless due to the development of multiple drug resistant strains. Therefore, identification of new drug targets is a valuable tool for the development of new treatments for affected patients and can be obtained by targeting essential protein(s) of CjR. We conducted this in silico study in order to identify therapeutic targets by subtractive CjR proteome analysis. The most important proteins of the CjR proteome, which includes chokepoint enzymes, plasmid, virulence and antibiotic resistant proteins were annotated and subjected to subtractive analyses to filter out the CjR essential proteins from duplicate or human homologous proteins. Through the subtractive and characterization analysis we have identified 38 eligible therapeutic targets including 1 potential vaccine target. Also, 12 potential targets were found in interactive network, 5 targets to be dealt with FDA approved drugs and one pathway as potential pathway based drug target. In addition, a comprehensive database 'CampyNIBase' has also been developed. Besides the results of this study, the database is enriched with other information such as 3D models of the identified targets, experimental structures and Expressed Sequence Tag (EST) sequences. This study, including the database might be exploited for future research and the identification of effective therapeutics against campylobacteriosis. URL: (http://nib.portal.gov.bd/site/page/4516e965-8935-4129-8c3f-df95e754c562#Banner).

Genome sequencing of two Bacillus anthracis strains: a virulent strain and a vaccinal strain

Bacillus anthracis strain SPV842_15 was isolated from bovine fetus, while B. anthracis strain Brazilian vaccinal was recovered from a commercial vaccine. We report here the genome sequences of both strains. The SPV842_15 genome is composed of a single circular chromosome with a length of 5,228,664 base pairs, and comprises 5911 coding sequences. In turn, the Brazilian vaccinal genome remains in 201 contigs with 5733 coding sequences. Both genomes have an overall C + G content of 35.4%, and 11 genes encoding the ribosomal RNAs (rRNAs) 5S, 16S and 23S. Only the plasmid pX01 sequence, which carries genes for toxins synthesis, was detected and completely assembled for both strains. These plasmids have a length of 181,684 base pairs and a C + G content of 32.5%. These genomic data generate insights about vaccinal B. anthracis virulence.

Extended low-resolution structure of a Leptospira antigen offers high bactericidal antibody accessibility amenable to vaccine design

Pathogens rely on proteins embedded on their surface to perform tasks essential for host infection. These obligatory structures exposed to the host immune system provide important targets for rational vaccine design. Here, we use a systematically designed series of multi-domain constructs in combination with small angle X-ray scattering (SAXS) to determine the structure of the main immunoreactive region from a major antigen from Leptospira interrogans, LigB. An anti-LigB monoclonal antibody library exhibits cell binding and bactericidal activity with extensive domain coverage complementing the elongated architecture observed in the SAXS structure. Combining antigenic motifs in a single-domain chimeric immunoglobulin-like fold generated a vaccine that greatly enhances leptospiral protection over vaccination with single parent domains. Our study demonstrates how understanding an antigen's structure and antibody accessible surfaces can guide the design and engineering of improved recombinant antigen-based vaccines.

Waning Immunity and Microbial Vaccines-Workshop of the National Institute of Allergy and Infectious Diseases

Since the middle of the 20th century, vaccines have made a significant public health impact by controlling infectious diseases globally. Although long-term protection has been achieved with some vaccines, immunity wanes over time with others, resulting in outbreaks or epidemics of infectious diseases. Long-term protection against infectious agents that have a complex life cycle and antigenic variation remains a key challenge. Novel strategies to characterize the short- and long-term immune responses to vaccines and to induce immune responses that mimic natural infection have recently emerged. New technologies and approaches in vaccinology, such as adjuvants, delivery systems, and antigen formulations, have the potential to elicit more durable protection and fewer adverse reactions; together with in vitro systems, these technologies have the capacity to model and accelerate vaccine development. The National Institute of Allergy and Infectious Diseases (NIAID) held a workshop on 19 September 2016 that focused on waning immunity to selected vaccines (for Bordetella pertussis, Salmonella enterica serovar Typhi, Neisseria meningitidis, influenza, mumps, and malaria), with an emphasis on identifying knowledge gaps, future research needs, and how this information can inform development of more effective vaccines for infectious diseases.

The exceptionally broad-based potential of active and passive vaccination targeting the conserved microbial surface polysaccharide PNAG

A challenging component of vaccine development is the large serologic diversity of protective antigens. Remarkably, there is a conserved surface/capsular polysaccharide, one of the most effective vaccine targets, expressed by a large number of bacterial, fungal and eukaryotic pathogens: poly-N-acetyl glucosamine (PNAG). Natural antibodies to PNAG are poorly effective at mediating in vitro microbial killing or in vivo protection. Removing most of the acetate substituents to produce a deacetylated glycoform, or using synthetic oligosaccharides of poly-β-1-6-linked glucosamine conjugated to carrier proteins, results in vaccines that elicit high levels of broad-based immunity. A fully human monoclonal antibody is highly active in laboratory and preclinical studies and has been successfully tested in a phase-I setting. Both the synthetic oligosaccharide conjugate vaccine and MAb will be further tested in humans starting in 2016; but, even if effective against only a fraction of the PNAG-producing pathogens, a major advance in vaccine-preventable diseases will occur.

Ion-Exchange Chromatography to Analyze Components of a Clostridium difficile Vaccine

Ion-exchange (IEX) chromatography is one of many separation techniques that can be employed to analyze proteins. The separation mechanism is based on a reversible interaction between charged amino acids of a protein to the charged ligands attached to a column at a given pH. This interaction depends on both the pI and conformation of the protein being analyzed. The proteins are eluted by increasing the salt concentration or pH gradient. Here we describe the use of this technique to characterize the charge variant heterogeneities and to monitor stability of four protein antigen components of a Clostridium difficile vaccine. Furthermore, the IEX technique can be used to monitor reversion to toxicity for formaldehyde-treated Clostridium difficile toxins.

A Size-Exclusion Chromatography Method for Analysis of Clostridium difficile Vaccine Toxins

High-performance size-exclusion chromatography (HPSEC or SEC) is a method that can be applied to measure size distribution of proteins, including aggregates, monomers, and fragments. In the biopharmaceutical industry the quantitation of aggregates contained in biotherapeutics and protein-based vaccines is critical given the potential impact on safety, immunogenicity, and efficacy. Hence, aggregation analysis of therapeutic proteins or protein-based vaccine products is almost always a requirement of regulatory agencies. SEC, also referred to as gel-filtration chromatography, separates molecules by size through a porous resin stationary phase. Under isocratic flow small molecules are retained on the column longer than large molecules. Here we describe the use of this SEC technique to characterize aggregation levels for four different protein antigens for a Clostridium difficile vaccine.

The Design of a Clostridium difficile Carbohydrate-Based Vaccine

Clostridium difficile vaccines composed of surface polysaccharides (PSs) have the potential to simultaneously control infection and colonization levels in humans. Hot water-phenol treatment of C. difficile biomass can extricate water-soluble PS-I and PS-II; and water- and phenol-soluble PS-III. C. difficile vaccines based on PS-II have attracted the most attention due its facile purification and ubiquitous expression by C. difficile ribotypes. Anti PS-II antibodies recognize both C. difficile vegetative cell and sporulating preparations and confer protection against C. difficile infection in a mouse model. The design of such an efficacious C. difficile PS-II conjugate vaccine is described here.

High-resolution melting-curve analysis of obg gene to differentiate the temperature-sensitive Mycoplasma synoviae vaccine strain MS-H from non-temperature-sensitive strains

Temperature-sensitive (ts⁺) vaccine strain MS-H is the only live attenuated M. synoviae vaccine commercially available for use in poultry. With increasing use of this vaccine to control M. synoviae infections, differentiation of MS-H from field M. synoviae strains and from rarely occurring non-temperature-sensitive (ts^–) MS-H revertants has become important, especially in countries where local strains are indistinguishable from MS-H by sequence analysis of variable lipoprotein haemagglutinin (vlhA) gene. Single nucleotide polymorphisms (SNPs) in the obg of MS-H have been found to associate with ts phenotype. In this study, four PCRs followed by high-resolution melting (HRM)-curve analysis of the regions encompassing these SNPs were developed and evaluated for their potential to differentiate MS-H from 36 M. synoviae strains/isolates. The nested-obg PCR-HRM differentiated ts⁺ MS-H vaccine not only from field M. synoviae strains/isolates but also from ts^– MS-H revertants. The mean genotype confidence percentages, 96.9±3.4 and 8.8±11.2 for ts⁺ and ts^– strains, respectively, demonstrated high differentiating power of the nested-obg PCR-HRM. Using a combination of nested-obg and obg-F3R3 PCR-HRM, 97% of the isolates/strains were typed according to their ts phenotype with all MS-H isolates typed as MS-H. A set of respiratory swabs from MS-H vaccinated specific pathogen free chickens and M. synoviae infected commercial chicken flocks were tested using obg PCR-HRM system and results were consistent with those of vlhA genotyping. The PCR-HRM system developed in this study, proved to be a rapid and reliable tool using pure M. synoviae cultures as well as direct clinical specimens.

Development and validation of a molecular size distribution method for polysaccharide vaccines

Determination of the molecular size distribution of vaccine products by high performance size exclusion chromatography coupled to refractive index detection is important during the manufacturing process. Partial elution of high molecular weight compounds in the void volume of the chromatographic column is responsible for variation in the results obtained with a reference method using a TSK G5000PWXL chromatographic column. GlaxoSmithKline Vaccines has developed an alternative method relying on the selection of a different chromatographic column with a wider separation range and the generation of a dextran calibration curve to determine the optimal molecular weight cut-off values for all tested products. Validation of this method was performed according to The International Conference on Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use (ICH). The new method detected product degradation with the same sensitivity as that observed for the reference method. All validation parameters were within the pre-specified range. Precision (relative standard deviation (RSD) of mean values) was < 5 per cent (intra-assay) and < 10 per cent (inter-assay). Sample recovery was > 70 per cent for all polysaccharide conjugates and for the Haemophilus influenzae type B final container vaccine. All results obtained for robustness met the acceptance criteria defined in the validation protocol (≤ 2 times (RSD) or ≤ 2 per cent difference between the modified and the reference parameter value if RSD = 0 per cent). The new method was shown to be a suitable quality control method for the release and stability follow-up of polysaccharide-containing vaccines. The new method gave comparable results to the reference method, but with less intra- and inter-assay variability.

Fast vaccine design and development based on correlates of protection (COPs)

New and reemerging infectious diseases call for innovative and efficient control strategies of which fast vaccine design and development represent an important element. In emergency situations, when time is limited, identification and use of correlates of protection (COPs) may play a key role as a strategic tool for accelerated vaccine design, testing, and licensure. We propose that general rules for COP-based vaccine design can be extracted from the existing knowledge of protective immune responses against a large spectrum of relevant viral and bacterial pathogens. Herein, we focus on the applicability of this approach by reviewing the established and up-coming COPs for influenza in the context of traditional and a wide array of new vaccine concepts. The lessons learnt from this field may be applied more generally to COP-based accelerated vaccine design for emerging infections.

Vaccination of feedlot cattle with extracts and membrane fractions from two Mycoplasma bovis isolates results in strong humoral immune responses but does not protect against an experimental challenge

Mycoplasma bovis is one of the most significant contributors to the bovine respiratory syndrome (BRD) that causes major losses in feedlot and dairy farms. Current experimental vaccines against M. bovis are ineffective and in some cases seem to enhance disease. Experimental infection with M. bovis induces a predominantly Th2 response and high levels of IgG1, which is an inferior opsonin and hence lacks protective capacity. In an attempt to induce a balanced (Th1/Th2) immune response, we have used CpG ODN 2007 as an adjuvant in a trial involving vaccination of cattle with M. bovis total extracts and/or membrane fractions and subsequent intranasal inoculation with an infective dose of M. bovis prepared from two different clinical isolates. Significant IgG1 serum responses were observed against both, extracts and fractions while IgG2 responses were significant against the extracts only. Proliferation of peripheral blood mononuclear cells (PBMC) after incubation with M. bovis cells was only observed in post-challenge samples of cattle vaccinated with both extracts and fractions but not in samples of cattle immunized with the membrane fractions alone. All groups showed transient weight losses and increased temperatures however, there were no significant differences in clinical parameters and survival rates between the groups.

Immunogenicity of Bartonella henselae P26 in cats

Cat scratch disease (CSD) has an estimated prevalence of approximately 200,000 persons in the USA, and approximately 22,000 new cases occur annually. Cats are the natural carriers of Bartonella henselae, the agent for CSD. Zoonotic transmission of B. henselae can result in CSD in immunocompetent humans and bacillary angiomatosis in immunosuppressed humans. Infection in cats often goes undetected. Development of a vaccine to prevent feline infection is warranted to reduce the prevalence of infection in the feline population and to decrease the potential for zoonotic transmission. One of the immunoreactive proteins identified from our previous study was P26. In this study, we demonstrated that B. henselae recombinant P26 (rP26) was immunogenic in cats. Four cats immunized with rP26 and four control cats were challenged with B. henselae type I and blood samples were collected for culture, PCR, and serology. Immunization with rP26 did not provide protection against B. henselae infection in cats at the doses used in this study. However, p26 PCR proved to be more sensitive for detection of infection in cats compared to gltA PCR. Furthermore, ELISA using rP26 as the substrate was more sensitive than ELISA using B. henselae type I outer membrane proteins.

Vaccine preparation by radiation processing

A new radiation biotechnology for the acquirement of a commercial vaccine, designed for prophylaxis of ruminant infectious pododermatitis (IP), produced by gram negative bacteria Fusobacterium necrophorum (F.n.), is presented. Two different processes for preparing F.n. vaccine are used: a) the inactivation of F.n. bacteria exotoxins by microwave (MW) or/and electron beams (EB) irradiation; b) the isolation of exotoxins from F.n. cultures irradiated with MW or/and EB and the inactivation of isolated F.n. exotoxins with formalin. The EB irradiation of F.n. cultures produced simultaneously with the cells viability decrease an increasing of exotoxin quantity released in the culture supranatant as compared with classical methods. The MW irradiation is able to reduce the cells viability to zero but without an increase of exotoxin quantity in cultures supranatant. Instead of this MW irradiation, for certain conditions, is able to induce an important stimulation degree of the F.n. proliferation in cultures, from two to three log10. Two vaccine types were prepared: A1 vaccine that contains whole cell culture irradiated with MW/EB and A2 vaccine that contains cell-free culture supernatant of an MW/EB irradiated F.n. strain producing exotoxins. Also, other two vaccines are prepared: B1 and B2 that contain the same materials as A1 and A2 respectively, but without using MW/EB exposure. The vaccine efficiency is tested in ruminant farms in which IP evolves. It is expected that this new vaccine to offer a better protection, more than 60%, which is the best presently obtained result in ruminant farms.

[Cloning and expression of hemolytic-toxin from Actinobacillus pleuropneumoniae and the immunoprotection in mice]

The ApxIIA, ApxIIIA, ApxIVA genes from Actinobacillus pleuropneumoniae serotype 3 and the ApxIA gene from Actinobacillus pleuropneumoniae serotype 5 were respectively cloned into the prokaryotic expression vector pGEX-5X-3. Then the recombinant expression plasmids were respectively transformed into E. coli BL 21 and fusion protein expression were induced by IPTG. The expression products were purified by precipitation with ammonium sulfate and chromatography on Sephadex G-200. SDS-PAGE indicated that the productsexpressed at a high level when the recombinant E. coli BL21 was induced 2h, joining IPTG to final concentration 1 mmol/L. Western blot analysis showed that the expression products had immunogenicity and specificity. Subunit vaccines were made by different purified expression products and Freund's adjuvant. Mice were immunized at 30 days and 45 days with the subunit vaccines. Then the mice were challenged with the APP of serotype 1, 3, 5, 7 or 10 at 60 days. The result of animal immunoprotection test showed that subunit vaccines (ApxIA + ApxIVA, ApxIA + ApxIIIA + ApxIVA, ApxIA + ApxIIA + ApxIIIA + ApxIVA) could offer 58.4%, 66.6%, 91.7% protection in mice against the challenge of serotype 1, 5 and 7 APP, respectively. These results suggested that the recombinant proteins had good immunogenicity and the subunit vaccine containing four kind of recombinant proteins could induce better immunoprotection.

[Construction, expression and purification of UreB-Omp11 fusion protein of Helicobacter pylori and its immunocompetence]

AIM

To construct H.pylori vaccine candidate strain expressing UreB-Omp11 recombinant fusion protein of H.pylori. To express and purify the fusion protein UreB-Omp11 and to determine its immunocompetence.

METHODS

The two genes were amplified by PCR, and the fusion gene ureB-omp11 was amplified by over lap extension PCR and then cloned into the fusion expression vector pET30a(+), pET28a(+) and pMAL-c2X. The appropriate expression system was selected, and the recombinant UreB-Omp11 fusion protein was expressed and indentfied by SDS-PAGE and Western blot analysis. Then the fusion protein was purified by MBP affinity chromatography and the purity was indentfied by SDS-PAGE. Then the fusion protein was immunized to mice. The immunized mice sera were analyzed by Western blot with purified fusion protein.

RESULTS

The ureB-omp11 fusion gene was correctly insected into pET30a(+) and confirmed by Enzyme digestion and sequencing analysis; Results in SDS-PAGE and optical density scanning demonstrated that this fusion protein MBP-UreB-Omp11 was expressed in the recombinant strain of E.coli TB1(pMAL-ureB-omp11). The fusion protein UreB-Omp11 was recognized by the mice sera immunized by H.pylori, the human sera infected with H.pylori and The purity of fusion protein was 90% after purification. The fusion protein purified could be recognized by corresponding antibody of mice sera immunized by this fusion piotein, This fusion protein has strong immunoantigenicity and immunoreactivity.

CONCLUSION

The prokaryotic expression system TB1 (pMAL-c2X-ureB-omp11) was successfully constructed and selected. The results obtained lay the foundation for research on development of protein and DNA vaccine of Hp.

Freeze-drying of live attenuated Vibrio anguillarum mutant for vaccine preparation

Vibrio anguillarum MVAV6203 is a mutant strain as a candidate of live attenuated vaccine. In vaccine preparation, the freeze-drying conditions of the strain were investigated to improve the survival after freeze-drying, including the protectant, rehydration medium, freezing temperature, and initial cell concentration. Vibrio anguillarum MVAV6203 is sensitive to freeze-drying and the viability was only 0.03% in the absence of protectant. Of the tested protectants, 5% trehalose with 15% skimmed milk gave the highest viability of 34.2%. Higher cell survival was obtained by quick freezing at -80 degrees C than slow freezing at -20 degrees C. Initial cell concentration was another important factor, preferable for 1-3 x 10(10)CFU/ml. The supplementation of 10% skimmed milk in rehydration medium improved obviously freeze-drying viability. The combination of the optimal conditions achieved 51.4% cell viability after freeze-drying.

A novel method to screen genomic libraries that combines genomic immunization with the prime-boost strategy

We employed a prime-boost regimen in combination with the expression library immunization protocol to improve the protective effectiveness of a genomic library used as immunogen. To demonstrate the feasibility of this novel strategy, we used as a prime a serogroup B Neisseria meningitidis random genomic library constructed in a eukaryotic expression vector. Mice immunized with different fractions of this library and boosted with a single dose of meningococcal outer membrane vesicles elicited higher bactericidal antibody titers compared with mice primed with the empty vector. After the boost, passive administration of sera from mice primed with two of these fractions significantly reduced the number of viable bacteria in the blood of infant rats challenged with live N. meningitidis. The method proposed could be applied to the identification of subimmunogenic antigens during vaccine candidate screening by employing expression library immunization.

[Purification and functional analysis of Helicobacter pylori UreB protein fragment]

OBJECTIVE

To establish an effective method for purification of Helicobacter pylori UreB fragment and conduct functional analysis of the purified protein.

METHODS

The protein fragment expression was induced by IPTG and the expressed protein was purified through affinity chromatography and ion-exchange chromatography. The purity of the fragment was determined by high-performance liquid chromatography (HPLC), and the specific biological activity of the purified fragment was assayed by urease activity inhibition test.

RESULTS

The protein fragment was highly expressed in E. coli with a purity over 91%. The protein fragment showed highly specific biological activity and the specific antibody induced by this fragment in rabbits could inhibit the activity of urease in a dose-dependent manner.

CONCLUSION

The UreB fragment with high purity and biological activity can be applied for further studies.