IMMUNOGENIC ACTIVITY OF A RIBOSOMAL FRACTION OBTAINED FROM MYCOBACTERIUM TUBERCULOSIS

From Kiyoshi Shiga to Present-Day Shigella Vaccines: A Historical Narrative Review

We are at an exciting moment in time with the advancement of many vaccines, including a shigella vaccine for the world. It is instructive to look at the long road that some vaccines have traveled to recognize the remarkable accomplishments of those who were pioneers, appreciate the evolution of scientific and applied technology, and inform the future history of a vaccine that would have great potential for global health. To achieve this valuable retrospective, a narrative historical literature review was undertaken utilizing PubMed and Embase databases with relevant search terms. Retrieved articles were reviewed and information was organized into historical themes, landmark discoveries, and important vaccine development parallels. The literature reviewed was synthesized into major eras of shigella vaccine development from pathogen discovery and first attempts to empirical approaches of killed whole-cell and live-attenuated approaches, and a modern era that applied recombinant DNA engineering and structural vaccinology. The history of shigella vaccine development has largely followed the evolutionary path of vaccine development over the last 120 years, but with important lessons learned that should be considered as we embark on the future chapters of bringing to the world a safe and effective vaccine for global health.

Bacterial Lysates as Immunotherapies for Respiratory Infections: Methods of Preparation

Bacterial lysates, prepared from the microorganisms most frequently involved in human Respiratory Tract Infections (RTIs) have been in the market for several decades, and at present, several different brands are available in many countries worldwide. They all claimed to exert local and systemic immunomodulatory effects but different clinical trials show disparate results between them. The lack of consistency of predicted therapeutic effects has undermined their clinical use and hampered licensing in several countries. One explanation for such lack of consistency in the results is that their methods of preparation are also very different. Here, we review the available literature describing methods of preparation of bacterial lysates, including patent disclosure documents. We found a great variety of methodologies of preparation and a lack of standardized procedures among them. The main conclusion of our study is that there is a clear need for standardized protocols of production to obtain comparable results in clinical trials worldwide.

Identification of Mycobacterial Ribosomal Proteins as Targets for CD4+ T Cells That Enhance Protective Immunity in Tuberculosis

Mycobacterium tuberculosis remains a threat to global health, and a more efficacious vaccine is needed to prevent disease caused by M. tuberculosis We previously reported that the mycobacterial ribosome is a major target of CD4⁺ T cells in mice immunized with a genetically modified Mycobacterium smegmatis strain (IKEPLUS) but not in mice immunized with Mycobacterium bovis BCG. Two specific ribosomal proteins, RplJ and RpsA, were identified as cross-reactive targets of M. tuberculosis, but the breadth of the CD4⁺ T cell response to M. tuberculosis ribosomes was not determined. In the present study, a library of M. tuberculosis ribosomal proteins and in silico-predicted peptide libraries were used to screen CD4⁺ T cell responses in IKEPLUS-immunized mice. This identified 24 out of 57 M. tuberculosis ribosomal proteins distributed over both large and small ribosome subunits as specific CD4⁺ T cell targets. Although BCG did not induce detectable responses against ribosomal proteins or peptide epitopes, the M. tuberculosis ribosomal protein RplJ produced a robust and multifunctional Th1-like CD4⁺ T cell population when administered as a booster vaccine to previously BCG-primed mice. Boosting of BCG-primed immunity with the M. tuberculosis RplJ protein led to significantly reduced lung pathology compared to that in BCG-immunized animals and reductions in the bacterial burdens in the mediastinal lymph node compared to those in naive and standard BCG-vaccinated mice. These results identify the mycobacterial ribosome as a potential source of cryptic or subdominant antigenic targets of protective CD4⁺ T cell responses and suggest that supplementing BCG with ribosomal antigens may enhance protective vaccination against M. tuberculosis.

Role of ribomunyl((r)) in the prevention of recurrent respiratory tract infections in adults : overview of clinical results

Recurrent respiratory tract infections (RRTIs) in adults are the result of an imbalance between lung defense mechanisms, and bacterial burden. Antibacterial treatments can temporarily restore the equilibrium between host and bacterial load, but do not prevent recurrence of infection. An alternative approach to prevent recurrence of infection is treatment with an immunostimulant, which provides immune protection against repeated bacterial and viral infection. All immunostimulant products are bacterial in origin: lysates (first generation immunostimulants), or bacterial extracts, like bacterial ribosomes, or membrane proteoglycans. This review highlights the current state of knowledge regarding the use of immunostimulants in adults with RRTIs, taking the ribosomal immunostimulant Ribomunyl((R)) as an example. Many studies are available on the mechanism of action and clinical efficacy in prevention of RRTIs in adults treated with Ribomunyl((R)). The effect of this immunostimulant on anti-infectious responses is explained by a stimulation of both nonspecific (innate) and specific (adaptive) immunity. In order to obtain a global overview of the therapeutic efficacy of Ribomunyl((R)) the most pertinent trials were selected from the literature based on adequate patient numbers and good methodology. Results of double-blind placebo-controlled trials using Ribomunyl((R)) for the treatment of different upper or lower RRTIs have demonstrated a statistically significant reduction in the number of infectious episodes and as a consequence, a decrease in antibacterial consumption, after 3 and 6 months of treatment. The tolerance profile of Ribomunyl((R)) was good in all studies. Economic evaluations suggest that savings can be made in healthcare expenditure, in patients with recurrent episodes of infection. It is concluded that Ribomunyl((R)) is effective in preventing and reducing upper and lower respiratory tract infections in adults. The product may also have an impact on reducing the development of bacterial resistance, as a result of fewer courses of antibacterials required to treat patients with RRTIs.

Genomic expression catalogue of a global collection of BCG vaccine strains show evidence for highly diverged metabolic and cell-wall adaptations

Although Bacillus Calmette-Guérin (BCG) vaccines against tuberculosis have been available for more than 90 years, their effectiveness has been hindered by variable protective efficacy and a lack of lasting memory responses. One factor contributing to this variability may be the diversity of the BCG strains that are used around the world, in part from genomic changes accumulated during vaccine production and their resulting differences in gene expression. We have compared the genomes and transcriptomes of a global collection of fourteen of the most widely used BCG strains at single base-pair resolution. We have also used quantitative proteomics to identify key differences in expression of proteins across five representative BCG strains of the four tandem duplication (DU) groups. We provide a comprehensive map of single nucleotide polymorphisms (SNPs), copy number variation and insertions and deletions (indels) across fourteen BCG strains. Genome-wide SNP characterization allowed the construction of a new and robust phylogenic genealogy of BCG strains. Transcriptional and proteomic profiling revealed a metabolic remodeling in BCG strains that may be reflected by altered immunogenicity and possibly vaccine efficacy. Together, these integrated-omic data represent the most comprehensive catalogue of genetic variation across a global collection of BCG strains.

Progress in the development of DNA vaccines against foot-and-mouth disease

DNA vaccines are, in principle, the simplest yet most versatile methods of inducing protective humoral and cellular immune responses. Research involving this type of vaccine against veterinary diseases began in the early 1990s and has since seen the evaluation of more than 30 important viral pathogens, including the economically important foot-and-mouth disease. With the demonstration that DNA vaccines protect against foot-and-mouth disease in sheep and pigs, and the advantages these DNA vaccines have over the conventional formulations, this approach may provide a better solution to the control of this disease. In this review, we provide a comprehensive overview of DNA vaccination strategies for foot-and-mouth disease reported in the literature, in which we highlight the studies that have reported protection in the key target species.

Immunogenicity of Ribonucleic Acid Preparations Obtained from Salmonella typhimurium

Mice immunized with purified whole-cell ribonucleic acid (RNA), RNA from the bacterial "particulate" fraction, and ribosome-associated RNA obtained from Salmonella typhimurium were found to be resistant to subsequent challenge infection with virulent salmonellae. Chemically, the immunogenic nucleic acid fractions contained from 1 to 3% "contaminant" material defined (based on the mean of 19 different preparations) as protein (0.24%), deoxyribonucleic acid (0.43%), methyl pentose (0.64%), hexose (1.58%), and undefined carbohydrate (0.76%). Heptoses and lipoidal material were not detectable in any of the immunogenic preparations examined. Physically, the nucleic acid preparations, after analytical ultracentrifugation, exhibited three boundaries similar to those reported elsewhere in comparable systems: 4 to 5S, 16S, and 23S. An evaluation of the immunity induced by the ribosome-associated RNA established that the immune response was (i) comparable to that induced 15 days postimmunization with live salmonellae and by ribosomal vaccines, but greater at 30 days postimmunization than that in mice immunized with attenuated salmonellae; (ii) dependent on the quantity of immunogen administered; (iii) dependent on the size of the infective inocula; (iv) inhibited at 15 but not at 30 days postimmunization when the immunogenic nucleic acid preparations were incorporated into Freund's incomplete adjuvant, (v) reduced or lost by dialysis in relatively high or low immunizing doses, respectively; and (vi) unaffected by enzymatic treatment of the preparations with trypsin, deoxyribonuclease, Pronase plus pancreatic ribonuclease, or pancreatic ribonuclease alone. The possible mode of action of ribosome-associated RNA in inducing an immune response to subsequent challenge infection with the homologous organism is discussed.

Specificity of Acquired Resistance Produced by Immunization with Listeria monocytogenes and Listeria Fractions

Mice were immunized with 1.0 mg of an attenuated strain of Listeria monocytogenes to determine the period of protection afforded by this strain when the mice were challenged intravenously with 5 MLD of listeria. Protection appeared 2 days after immunization and was still apparent 4 weeks after immunization. If the challenge dose was decreased to 1 MLD, protection was apparent at 10 weeks. Mice immunized with a comparable dose of mycobacterial cells and challenged intravenously with 1 MLD of listeria showed no protection at 10 weeks. The magnitude of the immune response to listeria challenge was not increased in mice immunized with the same virulent strain as that used for challenge. It was also found that resistance to listeria challenge appeared early after listeria immunization if the immunizing dose was large. As the immunizing dose was decreased and the challenge dose increased, resistance appeared later. Listeria killed by heat or ultraviolet irradiation, living but nonmultiplying streptomycin-dependent listeria, or listeria ribosomal fraction gave no protection against listeria challenge. The magnitude of the immune responses after listeria immunization to listeria challenge and to mycobacteria challenge were compared. It was found that protection after listeria challenge was of longer duration. In addition, a 100-fold larger vaccinating dose was required to give comparable protection against tuberculous infection.

Protection against pneumococcal infection by a ribosomal preparation

A subcellular extract prepared from nonencapsulated Diplococcus pneumoniae type 3 protected mice against a subsequent challenge with virulent D. pneumoniae types 1, 2, 3, and 7. Potency ratios ranged from 25 (type 3) to >1,175 (type 1). The immunity induced in mice by this preparation was best obtained by intraperitoneal inoculation followed by intravenous challenge. Mice immunized in this manner were protected up to 12 weeks and could withstand a challenge of several hundred LD(50). The protection was destroyed by treatment of the preparation with ribonuclease and was decreased by treatment with protease. The preparation consisted of 60.5% ribonucleic acid, 29.1% protein, 6.3% deoxyribonucleic acid, and 4.0% hexose. Ultracentrifugation studies indicated that this extract had five constituents which are compatible with ribosomal material.

Meta-analysis of published clinical trials of a ribosomal vaccine (ribomunyl) in prevention of respiratory infections

OBJECTIVE

To perform a meta-analysis using data from all clinical trials and studies of a ribosomal vaccine (Ribomunyl((R))) in order to estimate its overall effect on the number of infections and antibacterial courses used per person.

DESIGN AND SETTING

Meta-analysis of studies performed between 1985 and 1999 in 7 European countries and also in Kazakhstan, Tunisia, Morocco and Argentina.

PATIENTS AND PARTICIPANTS

Information from 14 213 adults and children.

RESULTS

There were 9 randomised, double-blind, placebo-controlled studies, 3 randomised nonblind studies and 16 nonblind studies with no placebo arm in which the response to ribosomal vaccine was compared with historical information. The mean number of infections per person in a study period of 3 months using placebo was found to be 2.39 (standard error +/- 0.50), and in a study period of 6 months was 3.35 (+/-0.41) infections. In both study periods, ribosomal vaccine use was associated with a reduction in the number of infections per person of 1.43 (+/-0.26). In the study period, patients on placebo reported 3.02 (+/-0.44) antibacterial courses, whereas ribosomal vaccine was associated with a reduction of 1.32 (+/-0.42) antibacterial courses.

CONCLUSIONS

In spite of variability in data quality, and the small sample size in some of the studies, we conclude that in patients with recurrent respiratory infections ribosomal vaccine significantly reduces both the number of infections and the number of antibacterial courses compared with placebo. This study is a strong and objective demonstration of the efficacy of ribosomal vaccine in limiting the number of otorhinolaryngological infections in children and adults.

Prevention of recurrent respiratory tract infections in children using a ribosomal immunotherapeutic agent: a clinical review

Recurrent respiratory tract infections (RRTIs) in children constitute a serious problem worldwide. Some children experience considerable morbidity as a result of RRTIs and receive repeated courses of antibacterials that are not effective against viral infectious agents and can increase bacterial resistance. Furthermore, the direct and indirect costs of RRTIs to the community are substantial. In this article, we review the available clinical evidence relating to use of the bacterial immunostimulant Ribomunyl for the prevention of RRTIs in children. The product is composed of ribosomal fractions from four bacteria involved in RRTIs as well as a membrane fraction from one of these bacteria (Klebsiella pneumoniae). Ribomunyl stimulates production of specific humoral and secretory antibodies against the four bacterial strains included in the compound. The product also stimulates non-specific immunity. Thus, Ribomunyl stimulates both the innate and acquired immune systems and offers preventive efficacy against both bacterial and viral infections. To perform this review, we searched the MEDLINE database for articles on Ribomunyl and then included only those publications that described placebo-controlled studies, complied with Good Clinical Practice standards, used the product in official registered indications, and administered it at the recommended dosages. In this way, we were able to generate a comprehensive profile of use of the product and draw valid conclusions about its clinical role. In clinical trials of children, Ribomunyl reduced the number of upper or lower RRTIs, the primary outcome measures. Other favorable results relating to efficacy parameters that served as secondary outcome measures in these studies included a reduction in antibacterial treatments, shorter duration of recurrent episodes, reduced need for other medications such as expectorants, smaller number of lost school days or parent absenteeism from work, less fever, and reduced hearing loss. Studies focusing on particular conditions, such as otitis media, or those that included specific patient groups, such as very young children, reported similar findings. Adverse events occurred very rarely and were mild. Their frequency was similar to that reported in placebo groups, and consisted mostly of fever, otorhinolaryngologic symptoms, and cutaneous events. In conclusion, this review clearly demonstrated that Ribomunyl is effective in preventing upper and lower RRTIs in children. Ribomunyl provided a reduction in the number, duration, and severity of infectious episodes and, thereby, reduced antibacterial use and the likelihood of consequent development of bacterial resistance. Ribomunyl also decreased absence from work or school, which has important economic consequences.

Ribosomal immunostimulation: assessment of studies evaluating its clinical relevance in the prevention of upper and lower respiratory tract infections in children and adults

OBJECTIVE

To review the efficacy of the ribosomal immunostimulant Ribomunyl in preventing upper and lower respiratory tract infections.

DESIGN AND SETTING

Review of studies of 3 and 6 months' duration comprising part of the international registration file.

PATIENTS

Data from 2117 patients (1215 children and 902 adults); ribosomal immunostimulant n = 1062, placebo n = 1055.

RESULTS

Nineteen randomised, double-blind, placebo-controlled clinical trials were performed between 1983 and 1994 in Europe. In children with ear-nose-throat (ENT) infections, 3 months' ribosomal immunostimulant treatment significantly decreased the mean number of recurrences (27-68% reduction), and reduced the duration of infection (28-66% reduction) and antibacterial requirement (29-60% reduction). Ribosomal immunostimulant was similarly effective in children with ENT and bronchopulmonary infections, reducing the mean number of recurrences by 32-61% compared with placebo. In children with otitis media, ribosomal immunostimulant reduced recurrences by 10-53% and also reduced the duration of infection, antibacterial use and local surgery requirement. Results obtained from studies of 6 months' duration confirmed or extended these results. In adult patients with ENT or mixed respiratory infections, ribosomal immunostimulant produced similar reductions to those seen in children for recurrent infections (54-78% reduction), duration of infection (42-79% reduction) and antibacterial use (38% reduction).

CONCLUSIONS

These results clearly demonstrate that ribosomal immunostimulant is effective in preventing and in reducing upper and lower respiratory tract infections in children and adults.

Characterization of M. Tuberculosis-derived IL-12-inducing material by alveolar macrophages

We have investigated the substance derived from Mycobacterium tuberculosis (Mtb) that induces interleukin (IL)-12 production by alveolar macrophages (AMs) in vitro. The cytosol fraction of live Mtb H37Rv induced IL-12 production by AMs in a dose-dependent manner. The addition of interferon-gamma (IFN-gamma) augmented IL-12 production. IL-12-inducing activity by AMs (termed as surely active keeping rescue antigen, SAKRA) was purified by gel filtration and ion exchange column chromatography, and the molecular weight of SAKRA was estimated by gel filtration to be more than 700 kDa. SDS-polyacrylamide gel electrophoresis (PAGE) and Western blotting of SAKRA using rabbit anti-SAKRA antibody suggested that SAKRA is composed with several low molecular weight proteins. Amino acids sequence analysis of several bands after SDS-PAGE suggested that SAKRA is a part of ribosomes. RT-PCR showed that SAKRA induced not only expression of IL-12 p40 mRNA, but expression of tumor necrosis factor (TNF)-alpha and inducible nitric oxide synthase (iNOS) mRNA at least 6 h after stimulation, suggesting that SAKRA activates the bactericidal activity of macrophages. To investigate the potential use of SAKRA as a vaccine against tuberculosis, SAKRA was administered to BALB/c mouse that had been immunized with BCG for 18 months, and mouse were infected with Mtb H37Rv via a respiratory route. Replication of Mtb in lungs and spleens was examined 6 weeks after infection. Administration of SAKRA to BCG-vaccinated mice significantly reduced the numbers of Mtb in lungs and spleens as compared with BCG-vaccinated control mice. Taken together, these results suggest that SAKRA is one of the Mtb-derived immunomodulatory substances which induce IL-12 production during infection and also increases mycobactericidal activities of macrophages, and that SAKRA may be a promising new vaccine candidate against tuberculosis.

Ribosomal immunotherapy for recurrent respiratory tract infections in children

Recurrent respiratory tract infections are common in children. They reflect the immaturity of the immune system in its encounter with environmental antigens. Little or no specific protective immune response has yet been established. These infections represent an important public health problem in terms of both treatment (anti-inflammatory or antibacterial drugs for children) and economy. Immunotherapy has been proposed as a means of preventing these recurrent infections by providing children with small doses of inactive bacterial antigens liable to trigger specific and protective immune responses. Among such drugs, ribosomal preparations (to which this review is limited) appear to be not only well tolerated, but also ideally targeted to induce mucosal responses. One preparation of ribosomal mucosal vaccine is commercially available in several countries. Numerous clinical trials in the world have confirmed the positive role of this mucosal ribosomal bacterial vaccine in significantly reducing the number of infections, courses of antibacterials, and absenteeism. In vitro and ex vivo investigations have confirmed that such vaccines indeed trigger protective specific immune responses.

Immunization of mice against Salmonella typhimurium using different DNA preparations

Groups of female BALB/c mice were given primary and booster injections of whole genomic DNA extracted from S. typhimurium, P. aeruginosa, or S. aureus. Other groups of mice were immunized in a similar manner with the 1.57kb fragment of the mouse virulence gene (mviA), pTargeT vector (plasmid DNA)/1.57kb construct, pTargeT vector, or saline. Mice in all groups were challenged intraperitoneally with 100 LD50 of S. typhimurium. The bacterial genomic DNA was extracted using the Pure Gene extraction kit. Specific primers were used to amplify the 1.57kb fragment by PCR. The pTargeT Mammalian Expression Vector System was used to prepare the plasmid/ 1.57kb construct. Bacterial genomic DNA extracted from P. aeruginosa and S. aureus appeared to induce non-specific resistance in mice. Specific, in addition to non-specific resistance appeared to be induced when genomic DNA from S. typhimurium was used. There was a prolongation of survival in the groups of mice that received either the 1.57kb fragment or the pTargeT vector/1.57kb construct and 16.67% and 33.34% respectively, of mice in each group survived at 40 days post challenge. None of the mice in the saline control group survived by day 7 post challenge. It is suggested that the non-specific resistance observed in this study might have been due to the adjuvant effect of the non-methylated CpG and other immunostimulatory motifs in bacterial DNA. Specific resistance obtained when genomic DNA from S. typhimurium was used might have been due to minute antigenic contamination, or virulence factor genes other than the mviA gene, might have been expressed in the host, which induced specific immunity.

Immunostimulatory effects of polar glycopeptidolipids of Mycobacterium chelonae for inactivated rabies vaccine

Humoral and cellular immune responses were analyzed with Fuenzalida-Palacios rabies vaccine associated with pGPL-Mc, polar glycopeptidolipids extracted from Mycobacterium chelonae, aiming at its use as adjuvant. These results were compared to those obtained with BCG, a well-known immunostimulator, under the same conditions. Rabies vaccine plus pGPL-Mc (2.5 mg/kg) induced a significant increase in serum neutralizing activity, in vitro lymphocyte proliferation (spontaneous, specific and mitogen stimulation) and delayed type hypersensibility. In addition, pGPL-Mc, as well as BCG, enhanced the vaccine potency. Our results support further studies to encourage the use of pGPL-Mc as an immunostimulator of veterinary vaccines, before consideration for human vaccines.

The potential use of heat-shock proteins to vaccinate against mycobacterial infections

Over the last few years, some of our experiments in which mycobacterial heat-shock protein (HSP) antigens were presented to the immune system as if they were viral antigens have had a significant impact on our understanding of protective immunity against tuberculosis. They have also markedly enhanced the prospects for new vaccines. We now know that the mycobacterial HSP65 antigen can confer protection equal to that from live BCG vaccine in mice.

Host immune responses to ribosome, ribosomal proteins, and RNA from Mycobacterium bovis bacille de Calmette-Gúerin

The ribosomes from BCG strongly induced delayed type hypersensitivity (DTH) skin reactions in guinea pigs immunized with live BCG or heat killed Mycobacterium tuberculosis H37Rv, and also induced lymphocyte proliferative response in mice immunized with ribosomes. In contrast, neither ribosomal proteins nor RNA alone induced both DTH skin reactions and lymphocyte proliferative responses. Particle form consisted of ribosomal proteins and RNAs might be absolutely required for the activation of immune responses.

Genetic vaccination against tuberculosis

New weapons are needed in the fight against tuberculosis. Recent research indicates that a vaccine better than BCG may be within reach. A diverse range of protein antigens can give encouragingly high levels of protective immunity in animal models when administered with adjuvants or as DNA vaccines. Accelerated arrest of bacterial multiplication followed by sustained decline in bacterial numbers are key parameters of protection and so the vaccine must target antigens produced by both actively multiplying and growth-inhibited bacteria. Consistent with this, the protective antigens have been found among secreted and stress proteins (e.g. Ag85, ESAT-6, hsp65, hsp70). Species-specific antigens are not needed, hence these remain available for diagnostic tests. Adoptive transfer of protection from vaccinated or infected mice into naive mice by transfer of purified T cells and clones shows that protection is expressed by antigen-specific cytotoxic T cells that produce interferon-gamma and lyse infected macrophages. These cells are produced in response to endogenous antigen. DNA vaccination appears to be an excellent way of generating these cells and may be able to give long-lasting protection.

Effectiveness of ribosomal fractions of Klebsiella pneumoniae, Streptococcus pneumoniae, Streptococcus pyogenes, Haemophilus influenzae and the membrane fraction of Kp (Ribomunyl) in the prevention of clinical recurrences of infectious rhinitis. Results of a multicenter double-blind placebo-controlled study

A multicenter, double-blind, placebo-controlled study was conducted to investigate the efficacy of an immunostimulant, Ribomunyl, in the prevention of recurrences of infectious rhinitis in adults. This trial involved 327 patients (168 Ribomunyl treated and 159 placebo cases) with an average of 4.3 +/- 1.8 rhinitis episodes per patient recorded during the year preceding the study. The main criterion of efficacy was the cumulative number of recurrences of infectious rhinitis during a 6-month follow-up period, as analyzed by standard tests. An additional analysis of relative risk of recurrences used multivariate failure for time data. Ribomunyl was effective throughout the study period, starting from the first month of treatment: a mean of 1.0 +/- 1.1 recurrences was recorded in the Ribomunyl group as compared to 1.5 +/- 1.4 recurrences in the placebo group; this indicated one-third fewer infections (P = 0.001). The protective effect of Ribomunyl on the relative risk for recurrences was estimated to be 0.58 by multivariate analysis (95% CI: 0.43-0.78, P = 0.0001). Analysis of secondary criteria also favored Ribomunyl: 38.5% less antibiotic courses per patient (0.8 +/- 1.3 vs 1.3 +/- 1.6; P = 0.002) and the number of days with antibiotics (5.6 +/- 9.3 vs 9.1 +/- 12.1; P = 0.002).

From Peyer's patches to tonsils. Specific stimulation with ribosomal immunotherapy

Ribosomal immunotherapy has been successfully used since the 1960s to boost the immune system and provide protection against microbial infections. We have investigated both whether and how these immunostimulants behave as natural immunogens in the mucosa-associated immune system. According to current understanding of the physiology of the mucosal immune response, intestinal Peyer's patches and the related solitary nodules are the primary inductive sites involved in the immune protection of all mucosal surfaces. Sensitised lymphocytes generated at these sites reach the general circulation through lymphatic drainage and relocate in mucosal areas by means of specialised 'high endothelial venules'. We hypothesised that orally administered ribosomal preparations would yield sensitised B cells specific for bacterial antigens from the parent strains. These cells should then be detectable in the peripheral blood after ribosomal intake, and identifiable as plasma cells in mucosae-associated tissues after completing their terminal differentiation. Ultimately, specific IgA should appear in secretions. To this end, we studied the immune responses generated in children and adults after 'Ribomunyl' administration, according to various consecutive protocols. The initial hypothesis was confirmed by the identification of specific B cells in the peripheral blood, plasma cells in the tonsillar tissue and specific IgA in the saliva. An animal model involving the use of twin sheep enabled detection of the specific cells in mesenteric and cervical lymph nodes. Analysis of these data indicates that ribosomal preparations trigger the production of lymphocytes specific for both ribosomes themselves and whole bacterial antigens. This supports the fact that small antigenic motifs are carried as partly synthesised peptides on the ribosomal particles. Therefore, ribosomes boost an array of B cells that are specific for many antigenic determinants of the bacteria from which they are extracted. We were also able to show that the stimulation provided was specific, since no response to other bacteria could be detected. Finally, analysis of the kinetics of this stimulation confirmed that oral immunisation generates rapid and transient secretory responses, building increased numbers of memory cells that are readily available to respond to further challenges by either more ribosomal preparations or potential pathogens.

Kinetics of specific salivary IgA responses in man after oral challenge by ribosomal immunostimulant

The kinetics of specific IgA mucosal responses was assessed in 12 healthy volunteers over 3 weeks of treatment by oral administration of an immunostimulant, Ribomunyl, composed of ribosomes from the four bacteria Streptococcus pyogenes, Streptococcus pneumoniae, Klebsiella pneumoniae and Haemophilus influenzae. The levels of IgA specific for these four bacteria increased after each immunization and, after the third week of treatment, were significantly higher than baseline day 0 values. This study demonstrates that oral ribosomal immunostimulation results in the production of specific salivary antibodies liable to recognize whole bacteria antigens, and therefore likely to confer protection. The kinetic analysis performed also demonstrates the rapidity of specific mucosal immune responses after oral stimulation in man, a feature still seldom explored.

Liposomes containing Candida albicans ribosomes as a prophylactic vaccine against disseminated candidiasis in mice

This study describes the development of prophylactic anti-Candida vaccine which combines the advantages of Candida albicans ribosomes as antigen(s) and of liposomes as carrier/adjuvant with minimal side-effects, which could be suitable for human use. The liposomal vaccine was composed of C. albicans ribosomes and the lipids dimyristoyl phosphatidyl choline (DMPC) and dimyristoyl phosphatidyl glycerol (DMPG) (9:1 molar ratio). Some of the vaccines contained Lipid-A (LA) as an additional adjuvant. The vaccine was prepared by two methods: (I) dehydration by lyophylization of small liposomes in the presence of the Candida ribosomes (DRV method); (II) colyophylization of DMPC/DMPG (9:1 mole ratio) in tertiary butanol with aqueous dispersion of Candida ribosomes. In both cases a dry powder was obtained which was rehydrated to form large multilamellar vesicles. The efficacy of the vaccines in mice was tested by their protectivity against a challenge with C. albicans, as assessed by survival rate, induction of cell mediated immunity (measured by delayed type hypersensitivity-DTH) and anti-Candida antibody titer. Unimmunized mice and mice vaccinated by ribosomes supplemented with incomplete Freund's adjuvant (IFA) were used as controls. The results indicated that the liposomal vaccines were effective at least as the IFA-based vaccine. The study indicates the feasibility of developing an efficacious anti-Candida vaccine for human use.

Adjuvanticity of pGPL-Mc and LRS in the immune responses of monkeys to oral immunization with diphtheria and tetanus toxoids

Experiments were carried out to examine the adjuvanticity of polar glycopeptidolipids of Mycobacterium chelonae (pGPL-Mc) or the London rocket seed (LRS) when combined with diphtheria and tetanus toxoids in an oral immunization of the African green monkey. The results showed that none of the monkeys receiving diphtheria and tetanus toxoids combined with 25 mg/kg of pGPL-Mc showed an increase in the the level of diphtheria antitoxin (DA) on the third and sixth weeks following the first and the second immunizations. One monkey from this group responded with increased seroneutralizing antibodies 3 weeks after the third feeding. On the other hand, one monkey, 3 weeks after the first immunization, and three monkeys, 3 weeks after the second and third oral vaccinations, showed an increase in specific anti-diphtheria antibody responses when the toxoids were combined with 25 mg/kg of LRS. The anti-diphtheria antitoxin responses of monkeys receiving diphtheria and tetanus toxoids combined with 50 mg/kg of pGPL-Mc or 50 mg/kg of LRS were significantly enhanced compared to the groups administered 25 mg/kg of the two adjuvants. The increase was observed in four out of five pGPL-Mc administered and in three out of five LRS-receiving monkeys. The results show that pGPL-Mc induced the highest titres of anti-diphtheria antitoxin compared to LRS, whereas the level of anti-diphtheria antitoxin titre of the two monkeys receiving the toxoids alone was less than 0.1 i.u./ml of serum throughout the experiment. According to the statistical analyses, no significant differences were recorded between the diphtheria antitoxin responses of monkeys following the first, second or third administration of LRS-adjuvated diphtheria and tetanus toxoids. However, a significant difference (P < or = 0.05) was observed in the diphtheria antitoxin response between the first and the second immunization of monkeys administered with toxoids adjuvated with 50 mg/kg of pGPL-Mc. The tetanus antitoxin responses of all monkeys were less than 0.1 i.u. of antitoxin per millilitre of serum throughout the study, which is considered not to be protective. However, we have recorded an anti-tetanus antitoxin titre of more than 0.2 i.u./ml of serum in one monkey that received diphtheria and tetanus toxoids combined with 50 mg/kg of pGPL-Mc.

Delayed-type hypersensitivity activity of the Brucella L7/L12 ribosomal protein depends on posttranslational modification

The ribosomal protein L7/L12 isolated from Brucella melitensis induces a delayed-type hypersensitivity (DTH) reaction in brucella-sensitized guinea pigs. Surprisingly, the recombinant brucella L7/L12 protein expressed in Escherichia coli as a fusion protein with a six-histidine tag cannot elicit such a reaction. The six histidines tagged to the recombinant L7/L12 protein were removed enzymatically, but the resulting protein did not induce a DTH reaction in sensitized animals. Incubation of the recombinant L7/L12 fusion protein in a B. melitensis lysate endowed the recombinant protein with a DTH activity, suggesting that the recombinant protein was modified by this treatment. Glycosylation or phosphorylation of the recombinant L7/L12 protein could not be detected. On the other hand, radiolabeled palmitic acid was found to be incorporated to the recombinant protein during its incubation in the brucella lysate. This incorporation was specific for the brucella L7/L12 protein and was inhibited when the brucella lysate was frozen and thawed before the incubation. The data reported here indicate that posttranslational modification of L7/L12 protein comprising at least an acylation step is required for the brucella L7/L12 DTH activity.

Protection against local Shigella sonnei infection in mice by parenteral immunization with a nucleoprotein subcellular vaccine

Nucleoprotein subcellular (NPS) vaccine, consisting of ribosome-bound O polysaccharide, was prepared from avirulent Shigella sonnei. NPS vaccine was tested for safety and protective activity in the mouse intranasal challenge model of Shigella infection. The vaccine was nontoxic when injected in doses up to 10,000 micrograms, and a single subcutaneous injection of as little as 0.1 micrograms gave significant protection against a lethal intranasal challenge with S. sonnei. These data demonstrate the induction of local protective immunity by parenteral immunization, support the concept of the ribosome as a potent vaccine vector, and give additional evidence for the protective activity of the NPS vaccine against Shigella infection.

Brucella ribosomal protein L7/L12 is a major component in the antigenicity of brucellin INRA for delayed-type hypersensitivity in brucella-sensitized guinea pigs

A delayed-type hypersensitivity (DTH) reaction in the course of brucellosis in humans and animals can be revealed by the brucellin INRA (Brucellergen) skin test. Brucellergen is composed of more than 20 proteins of different molecular weights. A 12-kDa protein eliciting DTH in Brucella melitensis Rev1-sensitized guinea pigs was found to be a significant component for the allergenic properties of Brucellergen. Sequencing of the gene encoding this protein identified it as the L7/L12 ribosomal protein. The L7/L12 gene of B. melitensis was amplified by PCR and subcloned in the Escherichia coli pQE30 plasmid. The resulting recombinant protein did not produce a DTH reaction in sensitized animals. It was used to raise specific antibodies in a rabbit. Affinity chromatography with these antibodies was used to isolate a single protein from Brucellergen and from B. melitensis cytosol preparations which produced a DTH reaction in guinea pigs sensitized with B. melitensis Rev1. N-terminal amino acid sequencing of the protein confirmed that it was the L7/L12 ribosomal protein. This is the first complete report on the involvement of a defined bacterial ribosomal protein in the DTH response of animals infected with intracellularly multiplying bacteria.

Bacterial crude extracts or ribosomes are recognized similarly by peripheral and mucosal B cells

Bacterial ribosomes have been shown to induce effective humoral and cellular immunological responses to whole microorganisms. In this study, the numbers of specific antibody producing cells directed towards Klebsiella pneumoniae, Streptococcus pneumoniae, Streptococcus pyogenes and Haemophilus influenzae ribosomes or whole bacteria sonicates were compared in the peripheral blood and tonsils of 7 children, and in the tonsils, mesenteric and cervical lymph nodes of 10 sheep. No significant difference was noted between the two types of antigens, confirming that ribosomal preparations are able to mimic the immunogenicity of whole bacteria in the mucosae-associated lymphoid tissue.

Immunological properties of ribosomal proteins from Mycobacterium bovis BCG

Two proteins with molecular mass 65 kDa, a heat shock protein, and an S1-like protein were found in a 30S ribosomal subunit from Mycobacterium bovis BCG. The 17-kDa protein in the 30S subunit was homologous to alpha-crystallin heat shock protein, and the 16-kDa protein in the 50S subunit was homologous to the L7/L12 protein. The latter provoked a strong delayed-type hypersensitivity reaction in the sensitized guinea pigs. The GroES-like protein (12 kDa) loosely associated with ribosomes.

Protective ribosomal preparation from Shigella sonnei as a parenteral candidate vaccine

A parenteral Shigella ribosomal vaccine (SRV) was investigated in animals for safety, antibody-inducing capacity, and protective activity. Ribosomal preparations from a Shigella sonnei phase I avirulent strain were obtained and shown to possess chemical, sedimentation, and other properties typical of bacterial ribosomes. No endotoxin contamination was revealed by a ketodeoxyoctonate assay, although the presence of some kind of O antigen was evidenced by serological findings and the high activity of SRV in inducing the O-antibody response and immunological memory in animals. SRV was nontoxic in mice, guinea pigs, and monkeys and induced no local reactions when injected subcutaneously in reasonable doses. Significant protection against a local Shigella infection (Sereny test) was seen in guinea pigs injected with SRV (efficiency index, about 60%) and the specificity of the protection was evident from cross-challenge experiments. The protective efficiency of SRV was especially high in rhesus monkeys challenged orally with virulent Shigella cells (89%, as calculated from the summarized data of several experiments in 71 animals). Protection in monkeys was long lasting and could be demonstrated several months after injection of SRV. An inexpensive technique can be used for the production of SRV on a large scale. The high immunogenicity of SRV is discussed in terms of the amplifying effect of the ribosome, which serves as a delivery system for polysaccharide O antigen. Further study of SRV as a candidate vaccine for humans seems justified by the data obtained.

Polysaccharide nature of O antigen in protective ribosomal preparations from Shigella: experimental evidence and implications for the ribosomal vaccine concept

Shigella ribosomal vaccine (SRV) was previously shown to be highly active in induction of mucosal and systemic O-antibody response and protection against Shigella infection in guinea pigs and monkeys. In this study, the O-specific component (OSC) was isolated from the SRV by affinity chromatography using rabbit O antibodies coupled to CNBr-Sepharose. The results of the reaction with carbocyanine dye as well as chemical data show that ribosomal OSC is devoid of lipid A and KDO, which are characteristic of classical LPS. The comparison of OSC with various LPS-related substances led to the conclusion that ribosomal OSC is similar to and probably identical with cytoplasmic O polysaccharide (L hapten), an O-side-chain polymer which accumulates in cytoplasm. It is hypothesized that the extremely high immunogenicity of SRV depends on a cooperative action of OSC, representing an epitope-specific part of the vaccine, and a ribosomal particle which serves as a vector, providing amplification of the immunogenic effect. The data obtained indicate the presence of a non-covalent link between the two components of the ribosomal vaccine.

Vaccination of mice against Leishmania mexicana amazonensis with microsomal fraction associated with BCG

Attempts to develop a satisfactory vaccine against New World cutaneous leishmaniasis have been made with varying success. We found that in mice, pretreated subcutaneously with 2 X 10(6) BCG organisms 2 weeks prior to immunization at the same site with as low as 10 micrograms of a microsomal preparation (Pol-F) of Leishmania mexicana amazonensis, a profound alteration was observed in the course of infection produced by inoculation of virulent amastigotes of the same strain. The BCG-Pol-F vaccine preparation was consistently shown to have a protective capacity associated with larger classical cellular immune response (skin test) and higher specific antibody titres in response to leishmanial challenge dose (1 X 10(6) amastigotes/mouse).

Vaccines against fungal infections

The state-of-the-art reached in developing protective immunity against fungal infections through vaccination makes a survey of methodologies and results timely. This review describes experimental vaccinations against dermatophytes, pathogenic yeasts, and dimorphic fungi with special attention to the anti-Coccidioides immitis vaccine, which has reached clinical trials, and to the anti-Candida albicans and anti-Histoplasma capsulatum ribosomal vaccines. Also covered are vaccination experiments in compromised hosts aimed at eliciting acquired resistance to opportunistic fungal infections which constitute risk factors for these hosts. Immunization procedures include live, killed, and attenuated organisms, as well as different subcellular fractions such as cytoplasmic extracts, fungal culture filtrates, cell walls, or ribosomal fractions. A variety of experimental animal models and isolated human trials constitute the subjects in these studies. Acquired immunity has been evaluated through assessment of resistance to infection and determination of specific immune responses. It has been demonstrated that fungal vaccines do elicit both humoral and cell-mediated immunity in the immunized host. For some vaccines (e.g., H. capsulatum), a correlation between the induced immunity and protection was observed and the immunity could be adoptively transferred. In view of the potential of vaccines against fungal infections, a perspective on their applicability, significance, and value for human use is discussed.

T-cell-independent macrophage activation in mice induced with rRNA from Listeria monocytogenes and dimethyldioctadecylammonium bromide

Purified rRNA from Listeria monocytogenes or Pseudomonas aeruginosa injected in combination with dimethyldioctadecylammonium bromide (DDA), protects mice nonspecifically against a lethal challenge of various extra- and intracellular bacteria. In the present study vaccination of BALB/c as well as C57BL/Ka mice with listerial RNA-DDA resulted in activation of fixed-tissue macrophages, as measured by an enhanced in vivo L. monocytogenes killing in spleen and liver. Evidence was found that macrophage activation by vaccination with rRNA-DDA occurred by a T-cell-independent mechanism. Treatment of mice with cyclosporin A had no effect on the enhanced L. monocytogenes killing induced with RNA-DDA; in vitro exposure of RNA-DDA to spleen cell cultures did not give rise to any lymphocyte proliferation. No evidence could be found for a possible adjuvant activity for RNA-DDA in cellular responses; in fact, RNA-DDA had an inhibitory effect on lymphocyte proliferative responses to Listeria antigen and to concanavalin A.

Ribonuclease-sensitive ribosomal vaccines

This paper presents an analysis of the protective properties of the components in ribonuclease (RNase)-sensitive ribosomal vaccines, in particular the ribonucleic acid (RNA). The protective activities in mice of purified ribosomes derived from Pseudomonas aeruginosa and from Listeria monocytogenes were compared. Both ribosomal vaccines had to be combined with the adjuvant dimethyldioctadecylammonium bromide (DDA) in order to be protective, and both lost their activity after RNase treatment. The ribosomal vaccines as well as RNA purified from the ribosomes induced non-specific protection. Intraperitoneal injection of RNA with DDA induced an influx of peritoneal cells. Furthermore, RNA with DDA activated macrophages as shown by, a.o., enhanced phagocytic activity and killing capacity for L. monocytogenes. The results suggest that the observed macrophage activation is probably T-cell-independent. With regard to the ribosomal vaccine of P. aeruginosa it is concluded that RNA also contributed to the protective activity by increasing the humoral response against suboptimal concentrations of contaminating cell surface antigens. In conclusion, it is proposed that ribosomal vaccines may be considered as a combination of a non-specific immunomodulator (RNA) with pathogen-specific cell surface antigens. This concept of ribosomal vaccines is discussed in relation to the literature concerning RNase-sensitive ribosomal vaccines.

Immunological evaluation of a component isolated from Mycobacterium bovis BCG with a monoclonal antibody to M. bovis BCG

A component of Mycobacterium bovis BCG referred to as BCG-a was isolated through the combined use of monoclonal antibody directed to BCG and affinity chromatography. Analysis of BCG-a by sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed a single prominent band with a molecular weight of ca. 10,000. Structural characterization of BCG-a consisting of amino acid composition and amino-terminal sequence determination was carried out. The intact BCG-a antigen was bound by neither the lectin from common lentils nor concanavalin A, implying that BCG-a does not carry any asparagine-linked oligosaccharides. Immunoprecipitation of 125I-labeled BCG-a with polyclonal and monoclonal antibodies directed against BCG resulted in bands having the same mobility on sodium dodecyl sulfate-polyacrylamide gel electrophoresis as did free 125I-BCG-a. In radioimmunoassays 125I-BCG-a was bound by the monoclonal antibody and by polyclonal antibodies from rabbits that had been immunized to BCG and to Mycobacterium tuberculosis H37Rv. Antibodies to nontuberculous and to nonacid-fast bacteria bound BCG-a poorly or not at all. The binding of 125I-BCG-a by the monoclonal antibody was readily inhibited by extracts of BCG and H37Rv, but it was not as readily inhibited by extracts of nontuberculous mycobacteria and was not at all inhibited by extracts of nonacid-fast bacteria. Considerable inhibition was similarly observed by surface antigens of nonviable, intact BCG organisms. Delayed cutaneous hypersensitivity reactions to small concentrations of BCG-a were elicited in guinea pigs that had been immunized with BCG or H37Rv antigens, but such reactions were not elicited in unimmunized animals.

A Streptococcus mutans immunogen that reacts equally with S. mutans antibody of all serotypes

We have studied a possible immunogen from S. mutans that has the capability of producing antibody to S. mutans which reacts equally well with all serotypes. This immunogen, a ribosomal preparation, is immunogenic in mice, is antigenic with rabbit anti-S. mutans, and is antigenic with the human antibody that also reacts with S. mutans. The human antibody is of the IgG class and S-IgA class.

Immunogenicity, biochemical and serological characterizations of ribosomal preparations from human oral strains of serotypes c and d of the bacterium Streptococcus mutans

Crude ribosomal preparations of Streptococcus mutans C67-1 (serotype c) and 50B4 (serotype d) contain protein RNA and carbohydrate. Sepharose CL-2B column chromatography of preparations yielded two distinct peaks. Cell-wall carbohydrates were predominantly present in peak I; the serological activity resided mainly in peak II. The preparations contained antigens which cross-reacted with several streptococcal Lancefield antisera. Antisera prepared against the preparations cross-reacted with cell-wall proteins (NaCl extracts) and Ag I/II, but not with cell-wall carbohydrate antigens (Rantz-Randall extracts). Thus, cell-envelope protein antigens in the preparations appear to be responsible for the serological activity. The unique properties of ribosomal preparations may, apart from serological cross-reactivity, be useful in the immunological protection against dental caries.

Effective immunity to dental caries: protection of gnotobiotic rats by local immunization with a ribosomal preparation from Streptococcus mutans

A ribosomal preparation from Streptococcus mutans 6715 was characterized for its ability to induce an immune response in gnotobiotic rats which was protective against S. mutans-induced dental caries. Animals injected in the salivary gland region with the S. mutans ribosomal vaccine developed significantly higher (P less than 0.01) salivary IgA and serum IgG antibody activities against whole S. mutans cells and ribosomal preparations than nonimmunized rats. Vaccinated animals had significantly lower (67%; P less than 0.01) levels of S. mutans adherent to their molar surfaces than the control rats after infection with the homologous, cariogenic S. mutans. The immunized animals had significantly fewer (P less than 0.01) carious lesions on their buccal, sulcal, and proximal molar surfaces than the nonimmunized rats following challenge with the virulent organism. Animals injected with the ribosomal preparation developed salivary IgA and IgG antibodies with specificities to various cell surface-associated antigens such as lipoteichoic acid and glucosyltransferase, suggesting that the observed protection may be due to antibodies against cell surface contaminants of the ribosomal vaccine. These results are the first demonstration that a ribosomal preparation from S. mutans protected rats from caries formation after challenge with the homologous, virulent S. mutans.

Opsonization and phagocytosis of Haemophilus influenzae type B organisms by mouse polymorphonuclear leucocytes and antiribosomal serum

Sera from rabbits immunized with ribosomes passively protect mice challenged with Haemophilus influenzae type b. The protective antibody interacted with organisms in the blood and possibly at the sites of dissemination, but not at the site of inoculation. Macrophages did not phagocytize oposonized bacteria in our system. However, immune serum enhanced phagocytosis and intracellular killing by polymorphonuclear leucocytes (PMN) by reducing viable counts by 77 to 93% and 35 to 50%, respectively. There was a strong correlation between opsonizing activity and passive protection in immune and normal serum. Inactivation of complement significantly reduced the opsonizing activity of the immune serum. A significant portion of the protection associated with the immune serum is localized in the IgM fraction. Immune serum, depleted of IgG, enhanced phagocytosis to a degree similar to intact immune serum. However, immune serum depleted of IgM, opsonized bacteria to the same degree as normal serum. Therefore, the immune component of serum responsible for protection and opsonization appears to be localized in the IgM fraction. These data indicate that protection induced by antiribosomal antibodies results from an interaction with the cell surface of H. influenzae organisms, leading to increased phagocytosis by PMN.

Immunogenicity of soluble and particulate antigens from Leishmania donovani: effect of glucan as an adjuvant

The protective efficacy of glucan as an adjuvant with killed promastigotes of Leishmania donovani was compared with that of soluble or particulate fractions of the parasite. When these vaccine preparations were injected either intravenously or subcutaneously in CF-1 mice, glucan potentiated resistance against L. donovani infections as reflected by significant reductions in hepatic amastigote counts relative to infected control mice. The leishmanial antigens alone afforded no protection. Serum direct agglutination titers to leishmanial antigens were highest in all groups given the vaccine intravenously, whereas the delayed-type hypersensitivity response to the antigen was positive only in groups immunized subcutaneously with glucan as an adjuvant. Some index of protection and immune response against visceral infection with the parasite was seen in groups vaccinated with glucan and soluble antigens. However, the protection afforded by glucan and particulate antigens of L. donovani more closely paralleled the resistance of mice treated with glucan and unfractionated killed promastigotes. Further antigenic analysis of particulate fractions of L. donovani may optimize effective immunization when used with appropriate adjuvants, e.g., glucan.

Analysis of cell wall and membrane contamination of ribosomal preparations from Streptococcus mutans

A ribosomal preparation from a cariogenic strain of Streptococcus mutans was examined for cell wall and membrane contamination. A biochemical characterization established that the preparation contained 61.0% RNA and 39.0% protein. Carbohydrate was not detected by phenol-sulfuric acid or methyl pentose assays. Glucosyltransferase and D-succinate dehydrogenase, which are cell wall- and membrane-associated enzymes, respectively, were not found. However, D-lactate dehydrogenase, another membrane-associated enzyme, was present in the preparation. A comparison of two-dimensional gel electropherograms of a mixture of cell walls and membranes and the S. mutans ribosomal preparation revealed contamination of the latter sample with at least six cell wall- or membrane-associated proteins. Adsorption of a rabbit antiserum raised against the ribosomal preparation with whole S. mutans cells abrogated antibodies directed against at least two proteins from the ribosomal preparation. Immunodiffusion plates showed reactivity of this antiserum against preparations of purified lipoteichoic acid from Streptococcus pyogenes and S. mutans. Adsorption of rat and rabbit antisera against the ribosomal preparation with the cell wall-derived materials glucosyltransferase, lipoteichoic acid, glucan, and a Rantz-Randall extract reduced the concentration of antibodies against the ribosomes by as much as 10-fold. These data indicated that the preparation was contaminated with at least six cell wall proteins, one cell membrane-associated enzyme, and lipoteichoic acid.

Immunogenic dialyzable factor derived from a ribosomal fraction of Salmonella typhimurium. I. Preparation of the protective dialyzable factor from the ribosomal fraction by the freeze-thaw procedure

The preparation, properties, and immunogenicity of the dialyzable factor from a ribosomal fraction of Salmonella typhimurium are described. The ribosomal fraction was purified to eliminate O-antigenic components, by affinity chromatography (Sepharose-anti-O antibody conjugates used as immunoadsorbent). The dialyzable factor was obtained in the concentrated dialysate of the purified ribosomal fraction which was alternately frozen in dry-ice acetone and thawed in an 80 C water bath, for a total of five or six cycles. When this preparation was tested for its ability to protect mice against challenge with 1,000 LD50 of the homologous bacteria, it afforded 100% protection at a dose equivalent to 5.0 micrograms of RNA. The protection conferred by this factor was mainly cell mediated but immune serum enhanced this immunity despite the fact that no antibodies were detected in it. The protective activity of this factor was sensitive to RNase digestion but resistant to proteolytic enzymes. Ion exchange chromatography of this factor with DEAE-Sephadex A-25 (in 7 M Urea-0.02 M Tris-HCl buffer, pH 7.5) resulted in a single A260 peak which was found to be immunogenic. Chemical analysis of this peak after it was concentrated and desalted revealed that this immunogenic fraction was composed mainly of mixed nucleotides. The data indicate that protective immunity conferred by a ribosomal vaccine is associated with RNA but may not require the intact RNA molecule.

Humoral and cell-mediated responses to a ribosomal preparation from Streptococcus mutans

Streptococcus mutans 6715 ribosomes disrupted in a Braun homogenizer were isolated in sodium dodecyl sulfate by differential centrifugation. This preparation contained 80% RNA and 20% protein, and carbohydrate was not detected by phenol-sulfuric acid and methyl pentose assays. The sedimentation coefficient of the ribosomes was 70S. After dialysis in 0.01 M phosphate buffer containing 10(-4) M MgCl2, the ribosomes dissociated into 54S and 32S particles. Leukocytes from rabbits immunized intramuscularly with the ribosomal preparation showed transformation and migration indices of 13.0 and 0.71, which were significantly different (P less than 0.05) from the respective indices of 0.9 and 0.98 in nonimmunized animals. Hyperimmune serum from these rabbits agglutinated representative Formalin-killed strains of all seven serotypes of S. mutans, inhibited adherence of live S. mutans 6715 to glass, and agglutinated S. mutans 6715 ribosomes adsorbed upon erythrocytes. These findings suggested that animals immunized with S. mutans ribosomes may be protected from caries caused by any of the seven serotypes of this organism.

Characterization of the immune response in subcutaneous chambers of guinea pigs immunized with a ribosomal preparation from Neisseria gonorrhoeae

Immunization of guinea pigs with ribosomal preparations has been previously shown to be protective against chamber infection with Neisseria gonorrhoeae, and this protection could be correlated with the presence of serum bactericidal antibody. Analysis of the chamber fluids from ribosome-immunized and nonimmunized guinea pigs has demonstrated that the chamber fluid may accurately reflect serum antibody levels and proteins. At least one major population of antiribosomal antibodies is present in both immune serum and chamber fluid as revealed by lines of identity between these components. Antibody- and complement-mediated bactericidal assays revealed that matched chamber fluids and sera from immune animals had comparable bactericidal titers. These results suggest that the antibody-complement-mediated bactericidal activity plays a major role in the protection against N. gonorrhoeae infection. Protection could not be explained on the basis of the cellular components of the inflammatory response since both immune and nonimmune chambers had comparable increases in polymorphonuclear neutrophils, monocytes, and lymphocytes after challenge.

In vitro kinetics of phagocytosis and intracellular killing of gonococci by peritoneal macrophages from mice deficient in complement component 5

Unstimulated resident peritoneal macrophages were harvested from complement-sufficient (C5+) and complement-deficient (C5-) mice by peritoneal lavage and cultured for 14 h. Adherence to cover slips was determined, and the monolayer was infected with transparent T1 gonococci. At various times after infection, the macrophages were observed for both attachment and phagocytosis of the gonococci by scanning and transmission electron microscopy. this analysis indicated that C5+ macrophages were capable of immediate phagocytosis of gonococci, with maximal phagocytosis occurring by 60 to 90 min. In contrast, C5- macrophages had a greater lag time before initiation of phagocytosis; this event was started by 30 min and completed by 90 min. The intracellular gonococci which were phagocytized by either C5+ or C5- mice were completely killed after 30 min of incubation. It appears that C5- mice are at a disadvantage in the early kinetics of the phagocytosis of gonococci, but that this does not affect the ultimate intracellular destruction of gonococci.

A microsomal fraction of Cryptococcus neoformans induces lymphocyte blastogenesis in infected guinea pigs

Differential centrifugation of a homogenate from a mechanically disrupted, acapsular isolate of Cryptococcus neoformans resulted in a 105,000 x g supernatant (105 K) and a microsomal fraction (MS), both of which were capable of eliciting specific delayed cutaneous hypersensitivity and in vitro blastogenesis in infected guinea pigs. Polyacrylamide gel electrophoresis revealed two major proteins in the MS and seven proteins in the 105 K fractions. Electron microscopy of the MS showed both membranes and ribosomes. In vitro lymphocyte blastogenesis elicited by 1 to 10 micrograms/ml of antigens was maximal after 4 days of incubation; the reacting populations were peripheral blood leukocytes (PBL) and peritoneal exudate cells (PEC). Spleen cells of infected animals were unresponsive to in vitro antigenic stimulation. A simplified schedule of priming animals was infection with a single dose of virulent cryptococci. Under these conditions 3 of 6 animals' PBL responded with stimulation ratios of 6.55, 21.1, 35.42 to the MS and 1.41, 9.33, 17.39 to the 105 K antigens at 1 microgram/ml. Four of six animals' PEC response were positive with stimulation ratios of 2.62, 2.72, 4.02 and 7.20 towards MS, and 2.62, 5.13, 5.71, 10.01 to the 105 K antigens at 1 microgram/ml. When small capsule and large capsule isolates were used for infection, the small capsule form was not isolated from the brain, in contrast to its isolation from 2 of 3 animals receiving large capsule forms. Two of three animals in each group responded with blastogenic indices more vigorous in the PBL, and the most potent antigen was MS. There was no obvious difference in lymphocyte reactivity between the two groups.

Role of outer envelope contamination in protection elicited by ribosomal preparations against Neisseria gonorrhoeae infection

A recent report (Cooper et al., Infect. Immun. 28:92-100, 1980) demonstrated that immunization of guinea pigs with ribosomal preparations was protective (approximately 90%) against chamber infections with Neisseria gonorrhoeae. Similar protection has been demonstrated with other cellular immunogens such as outer membranes (OM) (92%) or purified lipopolysaccharide (LPS) (83%). Protection of LPS (5 to 100 micrograms) was dose dependent (83% with 100 micrograms). Treatment of LPS with pronase reduced the protection by 50%. Ribosomal preparations contained LPS contamination (3.9%) based on dry weight determinations by 2-keto-3-deoxyoctonate analysis. Analysis of ribosomal preparations isolated from cells after lactoperoxidase-mediated 125I labeling indicated a major OM contamination (Protein I). The ribosomal preparation also contained low levels of succinic and lactic dehydrogenase. Passive hemagglutination tests revealed that sera from guinea pigs immunized with ribosomal preparations also demonstrated antibody to OM proteins and LPS. LPS was able to absorb one line of precipitation seen in immunodiffusion reactions as well as the bactericidal activity of such sera. OM preparations were unable to absorb the remaining precipitin line or remove the bactericidal activity. It appears that LPS is the major antigen responsible for the bactericidal activity seen in ribosome-immune sera.