The development of a process for culturing Bordetella pertussis immobilized on a polyurethane carrier

The processes of the cultivation of Bordetella pertussis, immobilized on polyurethane carrier in a fermenter, were carried out and studied. Acellular pertussis preparations were produced from the culture fluid obtained in the batch and multi-cycle cultivation processes with immobilized cells, as well as in the process with interrupted fermentation (for confirming the possibility of the preservation of cell viability). The content of protein and B. pertussis toxin in these preparations, as well as their leukocytes-stimulating and hemagglutinating activity, did not differ from similar characteristics of preparations obtained from culture fluid in homogeneous cultivation.     

Construction of the genetically attenuated bacteria Bordetella pertussis devoid of dermonecrotic toxin activity and producing modified nontoxic pertussis toxin form

The recombinant modified (attenuated) bacteria A. pertussis were constructed. These bacteria contained knockout mutation of the dnt gene and produced nontoxic pertussis toxin derivative. The immunological properties of the mutant bacteria B. pertussis strain KS were studied. The recombinant bacteria B. pertussis strain KS were found to be devoid of dermonecrotic toxin activity, conserved the structure of the mutant dnt gene in condition of cultivation on selective growth media, and long-term survival in laboratory animal organism. Intranasal immunization of mice with living bacteria B. pertussis, attenuated strain KS provided protection of animals from virulent strains of the pertussis. The efficiency of the protection was comparable with protection efficiency provided by standard corpuscular pertussis vaccine OSO-3.     

A study of the ability of Bordetella pertussis toxin to induce the formation of B-suppressors

Mouse spleen cells not adhering to the plastic surface and B-cells isolated from them were treated with B. pertussis toxin in vitro, washed and injected into recipients (allogeneic, syngeneic, intact or lethally irradiated) whose immune response to sheep red blood cells was then evaluated by Jerne's method. Treatment with B. pertussis toxin was shown to induce the development of immunosuppressive activity in intact spleen cells and in B-cells, to abolish the activity of memory B-cells and to enhance the suppressor activity of autoimmune mice. Supernatants obtained after autoimmune mice. Supernatants obtained after the 18- to 24-hour cultivation of spleen cells, previously treated with B. pertussis toxin for 60 minutes, suppressed the reaction of blast transformation of spleen cells to Con A and lipopolysaccharide and induced the appearance of immunosuppressive activity in intact spleen cells. The suppressing effect of the cells studied in this investigation may be linked with the ability of B. pertussis cells to stimulate the synthesis of cAMP, prostaglandins E and/or suppressor factors.     

Integrated development of an effective bioprocess for extracellular production of penicillin G acylase in Escherichia coli and its subsequent one-step purification

An integrated bioprocess for effective production and purification of penicillin G acylase (PAC) was developed. PAC was overexpressed in a genetically engineered Escherichia coli strain, secreted into the cultivation medium, harvested, and purified in a single step by anion-exchange chromatography. The cultivation medium developed in this study had a sufficiently low conductivity to allow direct application of the extracellular fraction to the anion-exchange chromatography column while providing all of the required nutrients for sustaining cell growth and PAC overexpression. It was contrived with the purposes of (i) providing sufficient osmolarity and buffering capacity, (ii) minimizing ionic species to facilitate the binding of extracellular proteins to anion-exchange media, and (iii) enhancing PAC expression level and secretion efficiency. Employing this medium recipe the specific PAC activity reached a high level at 871 U/g DCW, of which more than 90% was localized in the extracellular medium. In addition, the osmotic pressure and induction conditions were found to be critical for optimal culture performance. The formation of inclusion bodies associated with PAC overexpression tended to arrest cell growth, leading to potential cell lysis. Clarified culture medium was applied to a strong anion-exchange (Q) column and PAC was purified by non-retentive separation, where most contaminant proteins bound to the chromatographic media with PAC being collected as the major component in the flow-through fraction. After removing the contaminant oligopeptides using ultrafiltration, purified PAC with a specific activity of 16.3 U/mg was obtained and the overall purification factor for this one-step downstream purification process was up to 3 fold.     

Bordetella pertussis agglutinogens in cultivation dynamics

Bordetella pertussis growth phases during homogenous batch dynamic cultivation in the liquid medium as well as during the static cultivation on the solid medium were established. The maximal activity of agglutination reaction with antisera to B. pertussis agglutinogens 1, 2, and 3 was detected in bacterial culture at the end of exponential phase of growth. The activity of agglutination reaction decreased when cultures in stationary and death phases were used. During transition from exponential to death phase level of antibodies to agglutinogen 2 decreased by4 - 32 times. 2 - 4-fold decrease of antibodies level was observed when antiserum to agglutinogen 3 was used. Activity of agglutination reaction with antiserum to agglutinogen 1 was high and did not depend from phase of growth. When polyvalent antiserum to B. pertussis was used 4-fold decrease of antibody titers was observed in parallel with change of growth phases. Sera from rabbits immunized with B. pertussis cultures from the middle of exponential growth phase, the end of this phase, and begin of the death phase had high (maximal) level of agglutinating antibodies (6400), which was detected on 101 day after immunization with the former culture and on 31 day after immunization with either of the two latter cultures. To the end of experiment (292 day) titers decreased to 800, 3200, and 1600 respectively. These findings confirm an advisability of use of exponential growth culture for immunization of rabbits in order to obtain highly active diagnostic antisera to B. pertussis.     

Behavior of the inadvertent pH transient formed by a salt gradient in the ion-exchange chromatography of proteins

The inadvertent pH transient produced when a stepwise change in salt concentration is used as the eluent in ion-exchange chromatography was studied theoretically using a local-equilibrium theory and experimentally using both strong-base and weak-base anion-exchange column packings. The accuracy of the local-equilibrium theory was verified by comparing it to a full numerical solution of the governing partial differential equations obtained using the method of characteristics. The predictions from the local-equilibrium theory were observed to largely agree with experimental results. Detailed comparisons of experimental results and the local-equilibrium theory permitted the observed trends for the pH transients to be interpreted in terms of the physical properties of the column packing and mobile phase. The results of this study are useful for the design of ion-exchange processes using salt gradient elution where it is desired to limit the exposure of eluted proteins to the inadvertent pH transient caused by the salt gradient.     

Production of cell mass and pertussis toxin by Bordetella pertussis.

The cultivation of Bordetella pertussis affects production of pertussis toxin and biomass. Comparison of batch mode, chemostat operation and pHstat-turbidostatic control showed that productivities for the continuous process were greater than that for the batch operation. Continuous operation in balanced growth at the maximum specific growth rate, provided by the pHstat, resulted in the maximum specific production rate. Because of the strong association of pertussis toxin synthesis and cell growth, the concentration of toxin in the effluent of the continuous processes was greater than the maximum obtained in the batch bioprocess. An expanded Luedeking-Piret model of product formation kinetics fits the observed chemostat data and demonstrates that the production of pertussis toxin from the culture of B. pertussis is predominantly growth associated.     

Biologic characteristics of new Bacillus subtilis isolates

Characteristics of new Bacillus subtilis isolates from the environment and had high antagonistic activity were studied. Absence of virulence and toxin production allows to regard them as potential probiotic cultures. Growth media for cultivation of B.subtilis were chosen according to the principle of individual adequacy in system, which give the ability to optimize processes of cultivation, obtaining of inhibitory substances and antagonistic activity spectrum determination.     

Purification of cytochrome P450 BM-3 as a monooxygenase

After investigating two anion-exchange resins, the purification factor and activity yields of P450 BM-3 were higher with Resource Q than with DEAE-Sepharose FF. Screening of HIC media showed that Source 15ISO was the most suitable for purification of P450 BM-3. An effective isolation and purification procedure of P450 BM-3 was developed and included three steps: 35%-70% saturation (NH(4))(2)SO(4) precipitation, Source 15ISO hydrophobic interaction chromatograph and Sephacryl S-200 gel filtration chromatography. Using this protocol, the purification factor and P450 BM-3 activity recovery was 13.5 and 13.7%, respectively.     

Spontaneous phase variation in Bordetella pertussis is a multistep non-random process.

Pathogenic strains of Bordetella pertussis undergo spontaneous phase variation and become non-pathogenic upon culturing in vitro. Spontaneous variants of the Tohama and #165 pathogenic strains of B. pertussis were selected by their ability to grow on synthetic and semi-synthetic solid media. The frequency of these variants was between 10(-6) and 10(-7). About 250 variant strains were screened for the presence of virulence-associated traits, such as production of hemolysin, pertussis toxin and filamentous hemagglutinin (FHA). Only four different combinations of the traits were found: 7-11% of the variants displayed all traits, 17% of the variants carried the toxin and FHA, 5-11% carried FHA only and 66% were devoid of all virulence traits. The strains which had at least one virulence trait also demonstrated some adenylate cyclase activity. The disappearance of hemolysin quantitatively affected the other traits. These results suggest that phase variation in B. pertussis is a non-random process, involving multistep disappearance of virulence factors in the following order: hemolysin, pertussis toxin and FHA. In contrast, all 300 variants of strain #18323 of B. pertussis, which were able to grow on the selective solid media, carried all the virulence traits. This is in accordance with the strain's unique intracerebral growth capability.     

Purification and characterization of a calmodulin-sensitive adenylate cyclase from Bordetella pertussis

Bordetella pertussis, the bacterium responsible for whooping cough, releases a soluble, calmodulin-sensitive adenylate cyclase into its culture medium. B. pertussis mutants deficient in this enzyme are avirulent, indicating that the adenylate cyclase contributes to the pathogenesis of the disease. It has been proposed that B. pertussis adenylate cyclase may enter animal cells and increase intracellular adenosine cyclic 3',5'-phosphate (cAMP) levels. We have purified the enzyme extensively from culture medium using anion-exchange chromatography in the presence and absence of calmodulin and gel filtration chromatography. The enzyme was purified 1600-fold to a specific activity of 608 mumol of cAMP min-1 mg-1 and was free of islet activating protein. The molecular weight of the enzyme was 43 400 in the absence of calmodulin and 54 200 in the presence of calmodulin. The Km of the bacterial enzyme for adenosine 5'-triphosphate was 2.0 mM, whereas the Km of the calmodulin-sensitive adenylate cyclase from bovine brain was 0.07 mM. Although the enzyme was not purified to homogeneity, its turnover number of 27 000 min-1 is the highest documented for any adenylate cyclase preparation.     

Analysis of secreted protein profile and enzymatic activities from Corynebacterium diphtheriae and Bordetella pertussis on production batch media using peptide quenched fluorescent substrates

Proteases were identified and characterized from the culture supernatant of the C. diphtheriae and B. pertussis bacteria. The proteases were secreted in the media and detected at the end of the exponential growth phase. Activity was detected in some fluorescent substrates, based on selected protein sequences such as insuline beta-chain, bradykinin, and synaptobrevin. The proteases were purified by means of gel filtration chromatography. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis of the purified proteins indicated, for the main secreted proteins, an estimated molecular mass of 30 kDa in C. diphtheriae and 69 kDa in B. pertussis culture media. The proteases were stable and presented enzymatic activity at 37 degrees C. These proteases were not related to the main toxic compounds described in these two bacteria, but could represent good markers for the fermentation process when the enzyme activity was measured with the fluorescent substrates.     

Characteristics of the biological properties of a cell-free pertussis preparation

The biological properties of Bordetella pertussis antigenic complex, obtained by a technologically simple method from the medium used for the cultivation of B. pertussis, were studied. The preparation was characterized by pronounced hemagglutinating activity, toxicity, histamine-sensitizing and leukocytosis-stimulating activity and produced a cytopathogenic effect on the culture of Chinese hamster ovary cells. The detoxified preparations showed pronounced protective activity in experiments on the active and passive protection of mice. The ED50 of the preparation was 0.146 microgram of protein. In the proposed human immunization dose containing 10 micrograms of protein the detoxified preparation showed no hemagglutinating, leukocytosis-stimulating or histamine-sensitizing activity and proved to be nontoxic in the weight loss test on mice.     

The standardization of the in-vitro tetanus toxin neutralization test on Chinese hamster ovary cells

A test for the titration of B. pertussis toxin with antisera on Chinese hamster ovary (CHO) cells has been worked out. B. pertussis protective antigenic cell-free complex containing 48-54% of B. pertussis toxin has been used as antigen. The specificity of the effect of this complex on CHO cells has been confirmed in the toxicity neutralization test with antisera. CHO cells have been adapted to reagents and culture media made in the USSR. The titration of B. pertussis toxin and antisera on CHO cells did not require the use of highly purified antigen.     

Enhanced production of periplasmic interferon alpha-2b by Escherichia coli using ion-exchange resin for in situ removal of acetate in the culture

The possibility of using in situ addition of anion-exchange resin for the removal of acetate in the culture aimed at improving growth of E. coli and expression of periplasmic human interferon-α2b (PrIFN-α2b) was studied in shake flask culture and stirred tank bioreactor. Different types of anion-exchange resin were evaluated and the concentration of anion-exchange resin was optimized using response surface methodology. The addition of anion-exchange resins reduced acetate accumulation in the culture, which in turn, improved growth of E. coli and enhanced PrIFN-α2b expression. The presence of anion-exchange resins did not influence the physiology of the cells. The weak base anion-exchange resins, which have higher affinity towards acetate, yielded higher PrIFN-α2b expression as compared to strong anion-exchange resins. High concentrations of anion-exchange resin showed inhibitory effect towards growth of E. coli as well as the expression of PrIFN-α2b. The maximum yield of PrIFN-α2b in shake flask culture (501.8 μg/L) and stirred tank bioreactor (578.8 μg/L) was obtained at ion exchange resin (WA 30) concentration of 12.2 g/L. The production of PrIFN-α2b in stirred tank bioreactor with the addition of ion exchange resin was about 1.8-fold higher than that obtained in fermentation without ion exchange resin (318.4 μg/L).     

Importance of immunoelectrophoresis in agar and disc electrophoresis in polyacrylamide gel for characterizing different strains of Bordetella pertussis

The antigenic composition of typical and atypical B. pertussis strains obtained in the foci of pertussis infection, as well as experimentally obtained antibiotic-resistant B. pertussis strains, has been studied by the methods of immunoelectrophoresis in agar and electrophoresis in polyacrylamide gel (PAAG). Immunoelectrophoresis in agar has been found capable of differentiating B. pertussis culture from a group of unidentified morphologically similar Gram-negative bacilli by their antigenic composition and thus suitable for use as an additional criterion in the identification of atypical B. pertussis strains. PAAG electrophoresis has permitted finding differences in the set of protein antigens in the control strain and in its clones obtained by multiple subculturing in media with antibiotics added.     

Relationship of the sensitizing and protective properties of pertussis antigens

When comparing delayed hypersensitivity (DN) to B. pertussis corpuscular antigens with the agglutinogenic composition of B. pertussis, as well as to its histamine-sensitizing, leukocyte-sensitizing, adjuvant and hemagglutinating activity, no correlation was detected between the specific sensitizing properties of these antigens and the serotype and studied nonspecific properties of B. pertussis. The DH level correlated with the protective activity of B. pertussis corpuscular antigens and the ultrasonic fractions of B. pertussis. The close correlation of these two phenomena suggest that DH-inducing and protective B. pertussis antigens are identical, though their action has different manifestations, depending on the method of administration of the antigen preparation. On these grounds a new method for evaluating the immunogenicity of B. pertussis antigens is proposed. This method consists in comparing the sensitizing activity of the antigen under test and that of the national standard.     

Interaction of micro-dispersed forms of anionites and surface-active agents with serum albumin

The interaction of serum albumin with microdispersed forms of anion-exchange resins AV-16 GS and AV-17 I (USSR), obtained by mechanochemical destruction of polymers, and with low-molecular weight anionic (oleic acid, sulfonol) and cationic (cetazol, catamine) surfactants was being studied. Catamine and cetazol as well as microdispersions of anion-exchange resins are able to precipitate 90% of protein from the equilibrium solution, the content of protein in the initial solution being constant and equal to 6.5 mg/ml. Studies on the equilibrium in the system serum albumin--microdispersions of anion-exchange resins in the presence of ionogenic surfactants revealed that cationic surfactants are able to increase the amount of the precipitated protein, while in the presence of anionic surfactants the interactions between the protein macromolecules and microdispersions of polyelectrolytes become much weaker.     

The ornithine decarboxylase gene odc is required for alcaligin siderophore biosynthesis in Bordetella spp.: putrescine is a precursor of alcaligin.

Chromosomal insertions defining Bordetella bronchiseptica siderophore phenotypic complementation group III mutants BRM3 and BRM5 were found to reside approximately 200 to 300 bp apart by restriction mapping of cloned genomic regions associated with the insertion markers. DNA hybridization analysis using B. bronchiseptica genomic DNA sequences flanking the cloned BRM3 insertion marker identified homologous Bordetella pertussis UT25 cosmids that complemented the siderophore biosynthesis defect of the group III B. bronchiseptica mutants. Subcloning and complementation analysis localized the complementing activity to a 2.8-kb B. pertussis genomic DNA region. Nucleotide sequencing identified an open reading frame predicted to encode a polypeptide exhibiting strong similarity at the primary amino acid level with several pyridoxal phosphate-dependent amino acid decarboxylases. Alcaligin production was fully restored to group III mutants by supplementation of iron-depleted culture media with putrescine (1,4-diaminobutane), consistent with defects in an ornithine decarboxylase activity required for alcaligin siderophore biosynthesis. Concordantly, the alcaligin biosynthesis defect of BRM3 was functionally complemented by the heterologous Escherichia coli speC gene encoding an ornithine decarboxylase activity. Enzyme assays confirmed that group III B. bronchiseptica siderophore-deficient mutants lack an ornithine decarboxylase activity required for the biosynthesis of alcaligin. Siderophore production by an analogous mutant of B. pertussis constructed by allelic exchange was undetectable. We propose the designation odc for the gene defined by these mutations that abrogate alcaligin siderophore production. Putrescine is an essential precursor of alcaligin in Bordetella spp.     

Trial of pertussis toxin activity in vitro on CHO cells

The activity of B. pertussis toxin has been tested in the continuous culture of CHO (Chinese hamster ovary) cells. The in vitro method of testing B. pertussis toxin is rapid, highly sensitive and specific. The unit of activity of B. pertussis toxin is higher than in mouse tests by several orders. The specificity of the action of B. pertussis toxin on CHO cells has been confirmed by the test of the neutralization of the toxicity effect with antiserum.