Recombinant Production of a Novel Fusion Protein: Listeriolysin O Fragment Fused to S1 Subunit of Pertussis Toxin.

Background: Some resources have suggested that genetically inactivated pertussis toxoid (PTs) bear a more protective effect than chemically inactivated products. This study aimed to produce new version of PT, by cloning an inactive pertussis toxin S1 subunit (PTS1) in a fusion form with N-terminal half of the listeriolysin O (LLO) pore-forming toxin. Methods: Deposited pdb structure file of the PT was used to model an extra disulfide bond. Codon-optimized ORF of the PTS1 was used to make recombinant constructs of PTS1 and LLO-PTS1 in the pPSG-IBA35 vector. The recombinant PTS1 and LLO-PTS1 proteins were expressed in BL21 DE3 and SHuffle T7 strains of E. coli and purified by affinity chromatography. Cytotoxic effects of the recombinant proteins were examined in the MCF-7 cell line. Results: The purity of the products proved to be more than 85%, and the efficiency of the disulfide bond formation in SHuffle T7 strain was higher than BL21 DE3 strain. No cytotoxicity of the recombinant proteins was observed in MCF-7 cells. Soluble recombinant PTS1 and LLO-PTS1 proteins were produced in SHuffle T7 strain of E. coli with high efficiency of disulfide bonds formation. Conclusion: The LLO-PTS1 with corrected disulfide bonds was successfully expressed in E. coli SHuffle T7 strain. Due to the safety for human cells, this chimeric molecule can be an option to prevent pertussis disease if its immunostimulatory effects would be confirmed in the future.

PERISCOPE: road towards effective control of pertussis.

The resurgence and changing epidemiology of pertussis in high-income countries, the high infant mortality caused by pertussis in low-income countries, and the increasing morbidity in all age groups worldwide call for a concerted effort to both improve the current vaccines and develop new vaccines and vaccination strategies against pertussis. In this Personal View, we identify several key obstacles on the path to developing a durable solution for global control of pertussis. To systematically address these obstacles, the PERtussIS Correlates Of Protection Europe (PERISCOPE) Consortium was established in March, 2016. The objectives of this consortium are to increase scientific understanding of immunity to pertussis in humans induced by vaccines and infections, to identify biomarkers of protective immunity, and to generate technologies and infrastructure for the future development of improved pertussis vaccines. By working towards the accelerated licensure and implementation of novel, well tolerated, and effective pertussis vaccines, we hope to strengthen and stimulate further collaboration and transparency between the key stakeholders, including the public, the scientific community, public health institutes, regulatory authorities, and vaccine manufacturers.

Proteome Analysis Is a Valuable Tool to Monitor Antigen Expression during Upstream Processing of Whole-Cell Pertussis Vaccines.

Physicochemical and immunochemical assays were applied to substantiate the relation between upstream processing and the quality of whole-cell pertussis vaccines. Bordetella pertussis bacteria were cultured on a chemically defined medium using a continuous cultivation process in stirred tank reactors to obtain uniform protein expression. Continuous culture favors the consistent production of proteins known as virulence factors. Magnesium sulfate was added during the steady state of the culture in order to diminish the expression of virulence proteins. Changes in gene expression and antigen composition were measured by microarrays, mass spectrometry and ELISA. Transcriptome and proteome data revealed high similarity between the biological triplicates demonstrating consistent cultivation of B. pertussis. The addition of magnesium sulfate resulted in an instant downregulation of the virulence genes in B. pertussis, but a gradual decrease of virulence proteins. The quantity of virulence proteins concurred highly with the potency of the corresponding whole-cell pertussis vaccines, which were determined by the Kendrick test. In conclusion, proteome analysis provided detailed information on the composition and proportion of virulence proteins present in the whole-cell preparations of B. pertussis. Moreover, proteome analysis is a valuable method to monitor the production process of whole-cell biomass and predict the product quality of whole-cell pertussis vaccines.

Genetic verification of Bordetella pertussis seed strains used for production of Japanese acellular pertussis vaccines.

In Japan, the Bordetella pertussis strain Tohama provided by the National Institute of Health, Japan has been used for the production of acellular pertussis (aP) vaccines since 1981. In the present study, in order to verify the genetic consistency of B. pertussis vaccine seed strains, we analyzed the genetic properties of the working seeds obtained from five Japanese vaccine manufacturers, and compared them with those of B. pertussis Tohama reference strains (NIID L-7 and ATCC BAA-589). Genetic analyses with pulsed-field gel electrophoresis and allele typing showed 100% genetic identity among the five seed strains and the Tohama reference strains. In addition, Southern blot analyses revealed the absence of four orthologous genes (BB0537, BB0920, BB1149 and BB4885), which are specifically absent in the strain Tohama, and in the genome of all seed strains tested, suggesting that the regions of difference (RD11-RD14) are absent in their genomes. Consequently, no genetic difference was observed among the working seeds and Tohama reference strains. Our observations indicate that B. pertussis seed strains for Japanese aP vaccine production are genetically comparable with B. pertussis Tohama.

Scaling-up vaccine production: implementation aspects of a biomass growth observer and controller.

This study considers two aspects of the implementation of a biomass growth observer and specific growth rate controller in scale-up from small- to pilot-scale bioreactors towards a feasible bulk production process for whole-cell vaccine against whooping cough. The first is the calculation of the oxygen uptake rate, the starting point for online monitoring and control of biomass growth, taking into account the dynamics in the gas-phase. Mixing effects and delays are caused by amongst others the headspace and tubing to the analyzer. These gas phase dynamics are modelled using knowledge of the system in order to reconstruct oxygen consumption. The second aspect is to evaluate performance of the monitoring and control system with the required modifications of the oxygen consumption calculation on pilot-scale. In pilot-scale fed-batch cultivation good monitoring and control performance is obtained enabling a doubled concentration of bulk vaccine compared to standard batch production.

Development of safer pertussis DNA vaccine expressing non-toxic C180 polypeptide of pertussis toxin S1 subunit.

A toxic N-terminal 180-amino-acid fragment (C180) of pertussis toxin S1 subunit has the most potent ability to induce protective immunity against pertussis toxin (PT) following DNA-based immunization [Kamachi K, Arakawa Y. Infect Immun 2004;72:4293-6]. For the development of a safer pertussis DNA vaccine, three plasmids encoding mutant C180 (C180-R9K, C180-E129G and C180-R9K/E129G) were constructed and tested for their protective immunogenicity and cytotoxicity. All of the gene gun delivery of the plasmid, performed by inserting the mutant C180 gene into a mammalian expression vector pcDNA3.1, successfully induced anti-PT IgG antibody production without the loss of immunogenicity in mice. The immunizations of mice with the plasmids significantly inhibited leukocytosis-promoting activity by PT. Among stably transfected Chinese hamster ovary (CHO) cells expressing mutant C180, the expression of C180-R9K and C180-R9K/E129G was non-toxic to the transfectants, confirming that these mutant C180s have no cytotoxicity to mammalian cells. These results indicate that C180-R9K and C180-R9K/E129G genes, especially C180-R9K/E129G, are candidates for safe and effective antigen DNAs in the development of pertussis DNA vaccine.

Effect of relevant culture parameters on Pertussis Toxin expression by Bordetella pertussis.

Whooping cough vaccines are produced using different ranges of cultivation conditions and medium compositions, which are known to influence growth rate, virulence factor production and degradation, as well as the virulence factors' association to the cell. This study quantifies the impact of individual parameters on Pertussis Toxin (PT) production, using an optimized chemically defined medium as starting point, rather than a complex medium. A number of chemicals that are identified affect both growth rate and virulence factor production, which occur at similar levels in various commonly used production media. Also, degradation by proteolytic activity is shown to be an important parameter to monitor, since it significantly affects the PT yield. Low sodium concentrations, i.e. 50-75 mM rather than the conventional 100-140 mM, significantly increase the growth rate of the organism, the final optical density, as well as the association of PT to the cells. The absolute amount of biomass produced measured as dry weight, is similar for all sodium concentrations tested, contrary to earlier work. While it is known that high iron concentrations inhibit virulence factor production, it is shown here that iron-limited growth results in very high specific PT production. This finding may be used to produce a whole-cell vaccine with little biomass per dose, reducing whole-cell vaccine toxicity. The Bordetella pertussis strain 509 used here produces 30% more PT at 34 than at 37 degrees C, a commonly used cultivation temperature. The data in this study show that existing production processes for cellular and acellular vaccines can in principle be optimised considerably by taking simple measures.

[The expression of Bordetella pertussis protective antigens during bacterial multiplication on a medium with a fixed chemical composition]. / Ekspressiia protektivnykh antigenov Bordetella pertussis v protsesse razmnozheniia bakterii v srede opredelennogo khimicheskogo sostava.

The possibility of obtaining native pertussis preparations with high immunobiological activity has been shown. To obtain such preparations, the use of B. pertussis selected strain, its growth under the conditions of static cultivation in a synthetic culture medium and the use of supernatants with the maximum content of protective antigens with the aim of obtaining protective complexes are necessary.

[Optimization of the pertussis vaccine production process]. / Optimación del proceso de producción de la Vacuna Pertussis.

The production of Pertussis Vaccine was reevaluated at the Instituto Nacional de Higiene "Rafael Rangel" in order to optimise it in terms of vaccine yield, potency, specific toxicity and efficiency (cost per doses). Four different processes, using two culture media (Cohen-Wheeler and Fermentación Glutamato Prolina-1) and two types of bioreactors (25 L Fermentador Caracas and a 450 L industrial fermentor) were compared. Runs were started from freeze-dried strains (134 or 509) and continued until the obtention of the maximal yield. It was found that the combination Fermentación Glutamato Prolina-1/industrial fermentor, shortened the process to 40 hours while consistently yielding a vaccine of higher potency (7.91 +/- 2.56 IU/human dose) and lower specific toxicity in a mice bioassay. In addition, the physical aspect of the preparation was rather homogeneous and free of dark aggregates. Most importantly, the biomass yield more than doubled those of the Fermentador Caracas using the two different media and that in the industrial fermentor with the Cohen-Wheeler medium. Therefore, the cost per doses was substantially decreased.

Optimacion del proceso de production de la vacina pertussis / Optimization of pertussis vaccine production process

The production of Pertussis Vaccine was reevaluated at the Instituto Nacional de Higiene(r)Rafael Rangel(r) in order to optimise it in terms of vaccine yield, potency, specific toxicity and efficiency (cost per doses). Four different processes, using two culture media (Cohen-Wheeler and Fermentacion Glutamato Prolina-1) and two types of bioreactors (25 L Fermentador Caracas and a 450 L industrial fermentor) were compared. Runs were started from freeze-dried strains (134 or 509) andcontinued until the obtention of the maximal yield. It was found that the combination Fermentacion Glutamato Prolina-1/industrial fermentor, shortened the process to 40 hours while consistently yielding a vaccine of higher potency (7.91 +/- 2.56 IU/human dose) and lower specific toxicity in a mice bioassay. In addition, the physical aspect of the preparation was rather homogeneous and free of dark aggregates. Most importantly, the biomass yield more than doubled those of the Fermentador Caracas using the two different media and that in the industrial fermentor with the Cohen-Wheeler medium. Therefore, the cost per doses was substantially decreased

[Properties of an acellular preparation of Bordetella pertussis and its analysis after centrifugation in saccharose gradient]. / Wlasciwosci bezkomórkowego preparatu Bordetella pertussis i jego analiza po wirowaniu w gradiencie sacharozy.

Acellular preparations were studied which were obtained by a method of acidic extraction from culture of strain Tohama of Bordetella pertussis. Obtained preparations EM I and EM II were exhibiting property of leukocytosis stimulation and were respectively of following values: 43.5 and 19 u LPF/mg of protein. They also caused hemagglutination (150 and 19 u HA/mg of protein). Both preparations were exhibiting protective effect in intracerebral test performed on mice. After differentiation of EM I preparation by preparative centrifugation in saccharose gradient two fractions were obtained, of which lighter was exhibiting high hemagglutinating activity and leukocytosis stimulation (198 u LPF/mg of protein). Heaver fraction contained mainly endotoxin. Applied method permitted for partial purification of acellular preparation of B. pertussis; mainly decrease in its content of endotoxin responsible for high reactogenicity of pertussis vaccines.

Production of recombinant Bordetella pertussis serotype 2 fimbriae in Bordetella parapertussis and Bordetella bronchiseptica: utility of Escherichia coli gene expression signals.

Serotype-specific fimbriae of Bordetella pertussis are considered potential components of new-generation vaccines against whooping cough. Attempts to characterize fimbriae, and indeed other virulence determinants, produced by B. pertussis have been frustrated on one hand by low yields from B. pertussis itself and on the other by an inability to produce native recombinant products in Escherichia coli. In order to try to circumvent this problem, we have examined the expression of B. pertussis serotype 2 fimbriae in Bordetella parapertussis and Bordetella bronchiseptica from native as well as E. coli expression signals. These studies revealed that the fimbrial gene product was expressed from the original B. pertussis promoter and Shine-Dalgarno sequence in both B. parapertussis and B. bronchiseptica. The transcriptional start site of the gene was located 146 nucleotides upstream of its ATG start codon. A recombinant fimbrial subunit gene containing PLAC and the atpE translation initiation region of E. coli was also expressed in B. bronchiseptica. In all cases in which gene expression was detected the gene product was expressed as serotype 2-specific fimbriae as determined by enzyme-linked immunosorbent assay (ELISA) and immunoelectron microscopic investigation of the bacterial cell surface.