Effect of Bacteria and Bacterial Products on Antibody Response

A Quest for a Universal Plasma-Derived Antivenom Against All Elapid Neurotoxic Snake Venoms

This review describes the research aimed at the development of universal antivenom against elapid neurotoxic snake venoms. The antivenoms produced in Thailand in the 1980s were of low potency, especially against the elapid venoms. This was thought to be due to the low immunogenicity of the α-neurotoxins, which are the most lethal toxins in these venoms. Comparisons of various α-neurotoxin conjugates and polymers, and also different immunological adjuvants, showed that the adjuvant used is the major determinant in the antibody response in horses. The potent Freund's adjuvant was not used due to its severe local side-effect in horses. Therefore, a novel immunization protocol termed 'low dose, low volume multi-site' was developed for use in horses. This immunization protocol has led to the production of highly potent monospecific antivenoms against several elapid and viperid venoms, and two potent polyspecific antivenoms, one against 4 neurotoxic and another against 3 hematotoxic venoms. The immunization protocol has also led to other improvements in antivenom production including: several fold increases in antiserum potency, a reduction in the time required to reach therapeutically useful antibody titers, a 90% reduction in the amount of venom used, and 100% of the horses responding to the immunization program. This development is partly responsible for significant decrease in the Thailand's annual snakebite death toll from a few dozens to mostly nil in recent years. Finally, a simple and novel immunization strategy, using a 'diverse toxin repertoire' composed of numerous elapid toxin fractions as immunogen, was proposed and tested. This immunization procedure has resulted in the successful production of a widely paraspecific antiserum against at least 36 neurotoxic venoms of 28 species encompassing 10 genera and from 20 countries on four continents, and possibly against all elapid venoms with α-neurotoxins as the lethal toxins. These results indicate that, with optimizations of the composition of the 'diverse toxin repertoire', the immunization scheme and antibody fractionation to increase the antivenom neutralizing potency, an effective universal antivenom against the neurotoxic elapid snakes of the world can be produced.

Production and characterization of polyclonal and monoclonal Abs against the RNA-binding protein QKI

RNA-binding protein QKI, a member of the Signal Transduction and Activation of RNA family, is found to be essential in the blood vessel development and postnatal myelination in central nervous system (Woo et al., Oncogene 28:1176-1186, 2009; Lu et al., Nucleic Acids Res 31(15):4616-4624, 2003; Bohnsack et al., Genesis 44(2):93-104, 2006). However, its wide expression pattern suggests other fundamental roles in vivo (Kondo et al., Mamm Genome 10(7):662-669, 1999). To facilitate the understanding of QKI function in various systems, we prepared the polyclonal and monoclonal antibodies against QKI. To obtain the antigen, recombinant His-tagged QKI was expressed in Escherichia coli and highly purified by Ni(2+)-chelated column combined with hydrophobic and ion exchange methods. Following three types of immunizations with different adjuvants, including Freund's, PAGE gel, and nitrocellulose membrane, only the antiserum produced with Freund's adjuvant is effective for Western blot detection. Several McAb clones are able to recognize both endogenous and over-expressed QKI with high affinity in Western blot and immunofluorescence. The specificity of Ab was validated as weakening, and no specific signals were observed in cells with QKI knocking down. Immunohistochemistry analysis further showed positive staining of QKI in kidney where QKI mRNA was abundantly expressed, ensuring the wide applications of the QKI Abs in the ongoing mechanistic studies.

Adjuvants and Antibody Production: Dispelling the Myths Associated with Freund's Complete and Other Adjuvants

Adjuvants have been used for more than 70 yr to enhance the immune response of the host animal to an antigen. Among the mechanisms that adjuvants use to enhance the immune response are the "depot" effect, antigen presentation, antigen targeting, immune activation/modulation, and cytotoxic lymphocyte induction. The immunostimulatory properties of adjuvants result in inflammation, tissue destruction, and the potential for resulting pain and distress in the host animal. The inflammatory lesions produced by adjuvants such as Freund's complete adjuvant (FCA) have led some to conclude that pain and distress are present, even in cases where the scientific evidence fails to support this conclusion. Recommendations and regulations in the literature, based on available scientific evidence, provide guidance on total adjuvant volumes, volumes per site, routes of injection, booster injections, and adjuvants used for antibody production. Among the numerous adjuvants that are used for experimental antibody production reviewed in this article, many claim to be less inflammatory, tissue destructive, and painful than FCA while producing equal or superior antibody responses. Although no adjuvant surpasses FCA for experimental antibody production against a wide range of antigenic molecules, many produce excellent antibody responses with less inflammation and tissue destruction. Balancing the requisite degree of immuno-stimulation and the extent of inflammation, necrosis, and potential pain and distress requires consideration of the nature of the antigen, the host immune responsiveness, the adjuvant's mechanisms of action, and the desired end-product. In cases where the antigen is a weak immunogen or has a very limited availability, the type and role of adjuvant becomes a critical component in producing an acceptable immune response and humoral antibody response.

BHV-1 DNA vaccination: effect of the adjuvant RN-205 on the modulation of the immune response in mice

It is well documented that adjuvants improve the immune response generated by traditional viral vaccines, but less is known about the effects of adjuvants on the immune response elicited by DNA vaccines. In this study, we have investigated the use of RN-205 (immunomodulator containing a membrane rich in lipopolysaccharide from gram-negative bacteria) as an adjuvant and analyzed the humoral and cellular specific immune responses elicited by DNA vaccines based on the bovine herpesvirus-1 (BHV-1) glycoprotein D (gD). The comparison of the antibody response induced in mice by a mixture of the three different versions of DNA gD (membrane-anchored, secreted and cytosolic) formulated with or without RN-205 showed that the immunomodulator did not affect the total specific humoral response. The cellular immune response induced in mice immunized with vaccines plus RN-205 was higher than that obtained in mice vaccinated without RN-205, not only in the indexes of proliferation tests but in the number of IL-4 and gammaIFN secreting cells. When total spleen cells were marked with specific monoclonal antibodies against surface markers, a significant increase in the macrophage population of all the groups receiving RN-205 was observed. CD8 and CD4 positive cells were also increased but to a lesser extent. Our results indicate that the incorporation of RN-205 into DNA vaccines induces an increase of the cellular specific immune response in mice.

CpG DNA and LPS induce distinct patterns of activation in human monocytes

A specific set of immune functions is switched on in response to DNA containing unmethylated CpG dinucleotides in particular base contexts ('CpG motifs'). Plasmids, viral vectors and antisense oligodeoxynucleotides used for DNA vaccination, gene replacement or gene blockade contain immunostimulatory CpG motifs which may have independent biological activity. Although the immune stimulatory effects of CpG motifs on murine cells are well established, the evaluation of their possible effects on human cells is complicated by the higher LPS sensitivity of human leukocytes compared with those in mice. To address this issue, we analyzed CpG- and LPS-mediated immune activation of human PBMC. The biologic activity of LPS could be detected within 4 h using intracellular TNF staining of monocytes with flow cytometry at concentrations just one-twentieth (0.0014 Eu/ml) of the lower detection limit for the routinely used LAL assay (0.03 EU/ml). In contrast to the rapid LPS response, CpG DNA-stimulated TNF and IL-6 synthesis in human monocytes was not detectable until 18 h. E. coli DNA induced IL-6 synthesis in a concentration-dependent manner (30 micrograms/ml E. coli DNA; 409 pg/ml +/- 75 pg/ml, n = 7, IL-6 ELISA), but calf thymus DNA did not (< 10 pg/ml). Likewise, the CpG oligodeoxynucleotides 1760 (phosphorothioate) and 2059 (unmodified) induced IL-6 synthesis, but the corresponding control oligonucleotides 1908 and 2077 did not CpG DNA and LPS enhanced IL-6 synthesis synergistically. ICAM-1-expression of monocytes was increased 4.6-fold by E. coli DNA, 3.5-fold by 1760 and three-fold by 2059, compared with 3.6-fold by a maximal LPS stimulus and no change with non-CpG DNA. In conclusion, CpG-motifs induce TNF, IL-6 and ICAM-1 expression in human monocytes, but the kinetics of this differ from that induced by LPS, which makes it possible to distinguish immune activation by these agents. These results have important implications for the clinical development of therapeutic DNA in humans.

Enhancing activity of mycobacterial cell-derived adjuvants on immunogenicity of recombinant human hepatitis B virus vaccine

In a previous study, we demonstrated that a lipophilic derivative of muramyl dipeptide [MDP-Lys(L18)] augmented antibody response to recombinant human hepatitis B surface antigen (rhHBsAg) when it was co-immunized with rhHBsAg solubilized in PBS. Here, we examined adjuvant activity of two bacterial cell-derived adjuvants such as Bacillus Calmette-Guérin cell wall skeleton (BCG-CWS) and trehalose-6,6'-dimycolate (TDM), to enhance immunogenicity of rhHBsAg, comparing their activity with that of MDP-Lys(L18). In an animal model where mice were immunized subcutaneously (s.c.) with rhHBsAg (25 micrograms/mouse) admixed with 100 micrograms/mouse of BCG-CWS (Vac/BCG-CWS) or 50 micrograms/mouse of TDM (Vac/TDM) in o/w emulsion formulation, both mice immunized with Vac/BCG-CWS and Vac/TDM showed higher antibody titres to HB antigen than those of mice immunized with the recombinant vaccine alone. The activity of BCG-CWS and TDM to enhance antibody induction seemed to be almost the same with that of MDP-Lys(L18). Furthermore, the enhanced antibody response raised by these adjuvants was shown to be due to high titres of HB antigen-specific IgG1. In addition, the activity of these three adjuvants to enhance antibody response was shown to be higher than that of the present clinical vaccine, aluminium hydroxide-attached rhHBsAg (rhHBsAg-alum). In an analysis of delayed-type hypersensitivity (DTH) reaction where mice were immunized with rhHBsAg admixed with or without each adjuvant in o/w emulsion and followed by intrafootpad (i.f.) injection of rhHBsAg 4 weeks after immunization, mice immunized with Vac/BCG-CWS and Vac/TDM as well as Vac/MDP-Lys(L18) showed a significant increment of swelling reaction. These results suggest that BCG-CWS, TDM and MDP-Lys(L18) are potential adjuvants to enhance the immunogenicity of rhHBsAg to induce humoral and cellular responses.

Immunostimulatory DNA sequences function as T helper-1-promoting adjuvants

An adjuvant role for certain short bacterial immunostimulatory DNA sequences (ISSs) has recently been proposed on the basis of their ability to stimulate T helper-1 (Th1) responses in gene-vaccinated animals. We report here that noncoding, ISS-enriched plasmid DNAs or ISS oligonucleotides (ISS-ODNs) potently stimulate immune responses to coadministered antigens. The ISS-DNAs suppress IgE synthesis, but promote IgG and interferon-gamma (IFN-gamma) production. They furthermore initiate the production of IFN-gamma, IFN-alpha, IFN-beta, and interleukins 12 and 18, all of which foster Th1 responses and enhance cell-mediated immunity. Consideration should be given to adding noncoding DNA adjuvants to inactivated or subunit viral vaccines that, by themselves, provide only partial protection from infection.

Adjuvants--a balance between toxicity and adjuvanticity

Adjuvants have been used to augment the immune response in experimental immunology as well as in practical vaccination for more than 60 years. The chemical nature of adjuvants, their mode of action and the profile of their side effects are highly variable. Some of the side effects can be ascribed to an unintentional stimulation of different mechanisms of the immune system whereas others may reflect general adverse pharmacological reactions. The most common adjuvants for human use today are still aluminium hydroxide, aluminium phosphate and calcium phosphate although oil emulsions, products from bacteria and their synthetic derivatives as well as liposomes have also been tested or used in humans. In recent years monophosphoryl lipid A, ISCOMs with Quil-A and Syntex adjuvant formulation (SAF) containing the threonyl derivative of muramyl dipeptide have been under consideration for use as adjuvants in humans. At present the choice of adjuvants for human vaccination reflects a compromise between a requirement for adjuvanticity and an acceptable low level of side effects.

Induction of chronic polyarthritis in rabbits by hyperimmunization with Escherichia coli. I. Pathologic and serologic features in two breeds of rabbits

Hyperimmunization of 147 rabbits (outbred Japanese white rabbits and New Zealand white [NZW] rabbits bred in a closed colony) with heat-killed Escherichia coli 0:14 in Freund's incomplete adjuvant resulted in the animals developing a chronic polyarthritis resembling rheumatoid arthritis (RA). While both Japanese white and NZW rabbits showed a high incidence of the induced arthritis, a higher proportion of NZW rabbits developed the disease, suggesting that genetic influence is important in the development of RA-like illness. This experimental model may be useful for the study of RA.

Bacillus of Calmette and Guérin and 7,12-Dimethylbenz(α)-Anthracene Carcinogenesis in Mice

The effects of single or repeated Bacillus of Calmette and Guérin (BCG) treatment on the onset of tumors induced by the carcinogen 7,12-dimethylbenz (α) anthracene (DMBA) injected at birth into Swiss mice were studied. Multiple doses of BCG, given at regular intervals significantly lowered the incidence of carcinogen-induced tumors. The DMBA–induced lung adenomas did not differ morphologically from the ones that appeared in mice simultaneously treated with both DMBA and BCG.

Protection induced by inactivated influenza virus vaccines with polymethylmethacrylate adjuvants

Nanocapsules from a copolymer of polymethylmethacrylate and polyacrylamide were tested for adjuvant activity in mouse protection experiments with inactivated influenza virus as antigen. Viruses were either adsorbed on the capsules after polymerization or added to the monomers and incorporated by copolymerization after X-ray initiation. Both preparations showed enhanced immunity as compared to fluid vaccine, if the adjuvant content was 1%. The adjuvant effect was comparable to that caused by the mineral adjuvant Al(OH)3. After dilution of the polymer the adjuvant effect was lost. Such synthetic polymers at suitable concentrations could serve as alternatives to mineral adjuvants.

Immune response against hamster erythrocytes in the low-responder mouse strains. XI. Strain difference in the effects of various microbial adjuvants

Enhancing and suppressing effects of microbial adjuvants were studied in female mice of the C3H/He, AKR and SL strains. Propionibacterium acnes, Bordetella pertussis, BCG and yeast cell wall (YCW) were chosen as adjuvants. As antigens, we chose hamster erythrocytes (HRBC) which proved to be a weak antigen for mice. Adjuvants were given on day --7, day 0 or day 3, and HRBC were injected on day 0. The results were as follows. 1) P. acnes facilitated IgM and IgG antibody production in AKR mice and suppressed IgM antibody production in SL mice, when given on day --7. When P. acnes was given on day 0, they suppressed IgM antibody production in all of the strains used. 2) When B. pertussis was given on day 0, it exhibited enhancing effects on IgG antibody production in all of the strains and a suppressing effect on IgM antibody production in SL mice. 3) BCG suppressed IgM antibody production in all strains when given on day 0. 4) YCW showed no influence on antibody production in any combination used in this work. 5) SL mice were very sensitive to suppressing effects by adjuvants. Strain differences in the expression of enhancing and suppressing effects by adjuvants appear to be under some control independent of antigen-specific immune response genes.

Microbial adjuvant and autoimmunity. I. Induction of antibody responses to syngeneic tissue extracts in mice treated with capsular polysaccharide of Klebsiella pneumoniae

With the use of the capsular polysaccharide of Klebsiella pneumoniae (CPS-K) as a powerful adjuvant, high precipitin responses could be induced in mice to syngeneic eyeball extracts and thyroid gland extracts which were normally nonimmunogenic. Only very weak responses were induced to eyeball extracts by Freund's complete adjuvant. Repeated administrations of the antigens mixed with CPS-K at time intervals of 30 days (more than twice for the eyeballs or more than three times for the thyroid glands) were required for induction of high precipitin responses. Antibody responses detectable by the immunofluorescent technique could be induced to syngeneic lymphoid tissue extracts by injecting the mixture of antigen and CPS-K more than five times at time intervals of 30 days. These findings suggest that repeated stimulation by autoantigens together with such a strong adjuvant as CPS-K can terminate natural tolerance against autoantigens.

Studies on respiratory immunization with tetanus toxoid: the role of adjuvants

Aerosol vaccination of mice with purified plain tetanus toxoid does not induce an immune response unless a suitable adjuvant is added.Aluminium phosphate is without effect by aerosol treatment. Killed cells of Klebsiella pneumoniae, although effective, are unsatisfactory owing to the long inhalation period needed.Killed Bordetella perussis cells were found to be an excellent adjuvant. A single aerosol treatment with a toxoid-B. pertussis mixture during a moderate exposure period evoked a considerable immune response. With repeated aerosol treatment of primed mice the addition of adjuvant is not required; booster treatment with plain toxoid is at least as effective.Extracts from B. pertussis cells exert as good an adjuvant effect as the whole-cell vaccine. The remaining cell-wall debris also appears to be an active adjuvant.In combination with constant doses of adjuvant (10(8)B. pertussis cells), the 50% protective doses (ED 50) of toxoid were determined by inhalation and by s.c. injection and were found to be 0.1875 and 0.0625 LFU respectively. This would imply that, as a result of the adjuvant action, the s.c. ED 50 is reduced by approximately a factor of 20; whereas the respiratory ED 50 is decreased by at least a factor of 100.It is suggested that the much more pronounced adjuvant activity in aerosol immunization is associated with the induction of strong cell-mediated hypersensitivity in the respiratory tract.

Immunological aspects of asthma

Images

Antigenic Competition Between and Endotoxic Adjuvant and a Protein Antigen

Antigenic competition between bovine gamma globulin (BGG) and endotoxin from a smooth strain (S-ET) and a rough (R-ET) heptoseless mutant strain of Salmonella minnesota was studied in mice. Both endotoxins acted as adjuvants for enhancing the antibody response to BGG. However, other work showed that the R-ET had minimal antigenicity, and it was used as a control for the competition studies. Antigenic competition between BGG and endotoxin as expressed by a suppression of the antibody response to BGG could not be demonstrated when varying adjuvant doses of S-ET or R-ET were injected simultaneously with a small constant dose of BGG into normal mice. However, mice presensitized with S-ET several weeks before immunization with the S-ET and BGG combination produced anti-BGG levels which were four to eightfold lower than in normal mice. Nearly complete suppression of the anti-BGG response could be obtained in presensitized mice by reducing the BGG dose 10-fold or by increasing the adjuvant dose of endotoxin. Mice pretreated with R-ET and challenged with BGG plus S-ET or R-ET showed no depression of the anti-BGG response. These and other experiments confirmed the immunological basis of the competitive effect.