Factors affecting immunogenic activity of mycobacterial ribosomal and ribonucleic acid preparations

Immunogenic mycobacterial ribosomal and ribonucleic Acid preparations: chemical and physical characteristics

Five to 20% linear sucrose gradients were used to obtain sedimentation patterns of mycobacterial ribosomes, ribosomal subfractions, and ribonucleic acid (RNA) preparations. Classical 70S ribosomes were obtained when 10(-1)m magnesium chloride was used. These, when dialyzed against 10(-4)m MgCl(2), yielded typical 50S, 30S, and smaller ribosomal subunits. The 30S subunits were the most immunogenic under these conditions. A ribosomal preparation containing subunits which varied from 2.5 to 40S was fractionated by collecting five fractions from a sucrose gradient; based upon the amount of nucleic acid present, the fraction containing the 40S particles was most immunogenic. Physical and chemical evidence suggested that mycobacterial RNA preparations extracted with 65% ethyl alcohol from the ribosomes and diluted in distilled water, were either double-stranded, or mostly double-helical, or had a highly organized secondary structure. This was based on the following observations. (i) Native RNA was resistant to trace amounts of ribonuclease. (ii) The approximate T(m) value in SSC buffer (0.15 m NaCl plus 0.015 m sodium citrate) was greater than 85 C and in 0.1 SSC buffer was 55 C; the RNA diluted in SSC buffer produced a hypochromic effect on cooling at room temperature. (iii) Formaldehyde, in the presence of SSC buffer, decreased the T(m) of the RNA to approximately 55 C, and there was no hypochromic effect on cooling. (iv) Formaldehyde did not increase the wavelength of maximal adsorption of the RNA. (v) The purine/pyrimidine ratio was close to one. (vi) The major peak of the RNA sedimented in the more dense zones of the sucrose gradients. There was a relationship between the sedimentation pattern obtained with the RNA-protein subunits on sucrose gradients and immunogenicity; several examples are given. RNA-protein complexes of approximately 14 to 20S, and occasionally 23S in the major peak, appeared to produce the highest immune response. Smaller RNA-protein complexes such as 6S, which were obtained when the RNA preparation was diluted in certain buffers, were much less immunogenic. This was confirmed by collecting five fractions from sucrose gradients and finding the third fraction (containing RNA-protein complexes approximately 15 to 16S) the most immunogenic. Immunogenic activity was apparently related to the structure of the RNA since it was maximal when the RNA appeared to be either double stranded, double helical, or had a highly organized structure.

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.

Failure of synthetic polynucleotides to affect the immunogenicity of mycobacterial ribonucleic Acid and ribosomal protein preparations

The synthetic polyribonucleotides adenylic acid (poly A), uridylic acid (poly U), cytidylic acid (poly C), and inosinic acid (poly I), whether single- or double-stranded (poly A:U, poly I:C), cannot replace mycobacterial ribonucleic acid (RNA) in the production of a high immune response in CF-1 mice against tuberculous disease. These conclusions are based on the results of several types of experiments. (i) Poly A and poly U, used either singly or in combination, did not increase the immunogenicity of mycobacterial RNA preparations whether emulsified in Freund's incomplete adjuvant (FIA) or not emulsified. (ii) Mycobacterial ribosomal protein, extracted with 2-chloroethanol, was not immunogenic; the addition of poly A:U to the protein did not produce an immune response and FIA did not affect these results. (iii) The RNA left after the protein was extracted was partially immunogenic when emulsified in FIA even though it was partially degraded. (iv) Mycobacterial RNA prepared with ethyl alcohol and partially degraded with ribonuclease had a significantly lower immunogenic activity, and the original higher immune response was not restored by the addition of poly A:U. (v) Mycobacterial RNA totally degraded by weak alkali was not immunogenic, the original immunogenic activity was not restored by the addition of poly A:U or poly I:C, and FIA again did not influence the results. These findings suggest that (i) protein, polypeptides, or other antigenic fragments, if present, are not the specific immunogens; and (ii) mycobacterial RNA is responsible for the high immunogenic activity of mycobacterial ribosomal and RNA preparations. In addition, since the double-stranded forms of these synthetic polynucleotides markedly potentiate the formation of circulating antibodies, these results also reemphasize the lack of correlation between conventional antibody formation and immunity against tuberculosis.

Immunogenicity and protective efficacy offered by a ribosomal-based vaccine from Shigella flexneri 2a

Shigellosis is a major form of bacillary dysentery caused by Shigella infection. Shigella ribosome-based vaccines (SRV), considered among the potent vaccine candidates, are composed of O-antigen and ribosome isolated from S. flexneri 2a. To investigate the immunogenicity and protective efficacy of SRV, mice were vaccinated with SRV via the intranasal (i.n.) route. Interestingly, robust levels of Shigella-derived LPS-specific IgG and IgA Abs and antibody-forming cells were elicited in systemic and mucosal compartments following two i.n. administrations of SRV. Groups of mice receiving i.n. SRV developed milder pulmonary pneumonia upon challenge with virulent S. flexneri 2a than did those receiving parenteral SRV. We further found that the MyD88-dependent TLR2 signal partially mediates SRV-induced mucosal immunity, with the exception of TLR4- and TLR5-governed innate immunity. Most importantly, polymeric immunoglobulin receptor knockout (pIgR-/-) mice, which lack secretory IgA Ab, were afforded less protective efficacy than were wild-type mice. It can be concluded then that SRV is immunogenic and provides protective efficacy in mice. It can also be surmised that a mucosal SRV vaccine would be particularly relevant in targeting shigellosis, which provokes inflammation in the human colon.

Genetic analysis of host resistance: Toll-like receptor signaling and immunity at large

Classical genetic methods, driven by phenotype rather than hypotheses, generally permit the identification of all proteins that serve nonredundant functions in a defined biological process. Long before this goal is achieved, and sometimes at the very outset, genetics may cut to the heart of a biological puzzle. So it was in the field of mammalian innate immunity. The positional cloning of a spontaneous mutation that caused lipopolysaccharide resistance and susceptibility to Gram-negative infection led directly to the understanding that Toll-like receptors (TLRs) are essential sensors of microbial infection. Other mutations, induced by the random germ line mutagen ENU (N-ethyl-N-nitrosourea), have disclosed key molecules in the TLR signaling pathways and helped us to construct a reasonably sophisticated portrait of the afferent innate immune response. A still broader genetic screen--one that detects all mutations that compromise survival during infection--is permitting fresh insight into the number and types of proteins that mammals use to defend themselves against microbes.

Protective immunity to experimental tuberculosis by mannophosphoinositides of mycobacteria

Mannophosphoinositides isolated from mycobacterial cells were found to induce both humoral and cell-mediated immune responses in mice when injected as mannoside-methylated bovine serum albumin (MBSA) complexes. Immunization of mice with mannoside-MBSA complexes elicited significant protection against challenge with LD50 dose of M. tuberculosis H37Rv as revealed by high survival rate, low values of root-specific lung weight, lung densities and colony forming units recovered from lung, liver and spleen, compared to the nonimmunized group. These observations were further substantiated by histopathological studies. The protective immunity elicited by mannoside-MBSA complexes against challenge with M. tuberculosis H37Rv was mediated by the cooperation of T-B cells, as shown by the passive transfer of immune cells/sera into syngeneic sublethally irradiated recipient mice.

Dissociation between enhanced resistance and delayed hypersensitivity induced with subcellular preparations from Listeria monocytogenes and the adjuvant dimethyl-dioctadecyl-ammonium bromide

In this study we investigated the relation between enhanced resistance and delayed hypersensitivity (DH) induced with subcellular preparations from Listeria monocytogenes and the adjuvant dimethyldioctadecylammonium bromide (DDA). Ribosomal RNA as well as cell envelope fragments (fraction I) protected mice against lethal Listeria infection. However, only fraction I induced DH against killed Listeria. For the induction of protection with fraction I or RNA as well as for the induction of DH with fraction I, preparations had to be administered in combination with DDA. Fraction I elicited a DH response in mice immunized with viable Listeria, but RNA did not. These observations pointed to a dissociation between DH and enhanced resistance induced with RNA, and to a dissociation between fraction I and RNA with respect to their ability to induce or elicit DH. Also DH and enhanced resistance induced with fraction I could be dissociated. Intracutaneous administration of fraction I induced high levels of DH without concomitant induction of protection against lethal challenge with Listeria. On the other hand, intraperitoneal administration of fraction I fully protected mice against lethal infection, but only induced a moderate DH response. DH induced with fraction I was largely specific, whereas enhance resistance induced with this preparation was nonspecific. Finally, proteinase K-sensitive proteins were found to be essential for the induction of DH but not for the induction of protection with fraction I.

Lack of cross-reactivity of antibodies to ribosomal preparations from Streptococcus mutans with human heart and kidney antigens

Previous studies have suggested that sera from animals immunized with whole Streptococcus mutans cells may cross-react with human and monkey heart sarcolemmal tissues. In the present study, sera and saliva from rats and rabbits immunized peripherally with ribosomal preparations from S. mutans 6715 (serotype g) or GS-5 (serotype c) were examined for their ability to react with normal human heart sarcolemmal and kidney glomerular tissues by using enzyme-linked immunosorbent and immunofluorescence assays. The results showed that antibodies to serotype g and c ribosomal preparations do not react with either the human heart or renal antigens. Sera from mice immunized with human heart tissue and from a patient with a high anti-streptolysin O titer reacted strongly with human heart sarcolemmal and kidney glomerular tissues. These data indicated that ribosomal preparations from S. mutans lack the putative human heart cross-reactive determinant and suggest that the use of an S. mutans ribosomal vaccine against dental caries may not be pathogenic to human heart or renal tissues.

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.

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.

Kinetics of Haemophilus influenzae type B infection in normal and ribosome-immunized mice using intraperitoneal and intracerebral routes of inoculation

The kinetics of infection was studied in normal and ribosome-immunized mice challenged with Haemophilus influenzae Type b organisms. Ribosomal preparations extracted by the differential-centrifugation and sodium-dodecyl-sulphate treatment or ammonium-sulphate-precipitation procedures were highly immunoprotective when mice were challenged by the i.p. route. After i.p. injections, organisms rapidly spread to blood, liver, lungs and brain in normal and immunized mice. However, by 24 h after injection, evidence of organism clearance could be seen in immunized mice. By 32 h organisms were cleared from blood, brain and lungs of all immunized mice and from spleens in 2 of 3 mice. However, organisms persisted in high numbers of unimmunized mice until their death by 48 h. These data indicate that i.p. injections of H. influenzae mixed with gastric mucin leads to a true infection and can be used as a model to evaluate immunoprotective activity. The kinetics of infection induced by intracerebral (i.c.) inoculation also was studied. The LD50 for this type of infection was more than 1000 times the LD50 for i.p. infection. The patterns of infection induced by i.c. challenge were similar in normal and immunized mice and immunoprotection could not be detected using this model.

Immunogenicity of ribosomal preparations from Neisseria gonorrhoeae

Protection against gonococcal infection was obtained by immunization with ribosomal preparations from Neisseria gonorrhoeae. Ribosomes were isolated from disrupted cells by differential ultracentrifugation and treatment of the microsomal fraction with 0.25% sodium dodecyl sulfate. The isolated ribosomal preparations contained 55% ribonucleic acid, 39% protein, and 0.35% carbohydrate. The ribosomal preparations contained small amounts of endotoxin as determined by thiobarbituric acid- and lead acetate-sensitized mice assays. Guinea pigs immunized subcutaneously with ribosomal preparations were challenged intrachamberially with 10(7) colony-forming units of N. gonorrhoeae, and protection was assessed by clearance of the organism from subcutaneous chambers. The ribosomal preparations elicited significant protection, which was enhanced by incoporation of the immunogen into adjuvant. This protection was comparable to that obtained with whole cells. Treatment with proteolytic enzymes destroyed the protective effect of the ribosomal preparations, but ribonuclease had no measurable effect. Passive hemagglutination and immunodiffusion tests with sera from immunized animals demonstrated the presence of antibody to the ribosomal antigens. Results of adsorption of antiribosomal sera with enzyme-treated ribosomal preparations also indicated the protein nature of the immunogen. These results indicate that protein associated with the gonococcal ribosomal preparation is the major protective immunogen. The role of endotoxin contamination in the immunogenicity of gonococcal ribosomal preparations warrants further investigation.

Immunogenicity of ribosomes from enzymatically lysed Streptococcus pyogenes

Ribosomal fractions isolated from Streptococcus pyogenes by physical and enzymatic disruption of the cell wall were found to provide protection in mice against challenge with the homologous M type. Although ribosomal fractions isolated by physical disruption of the cells also provided protection against challenge with several heterologous M types, ribosomal fractions from enzymatically lysed cells did not provide protection against any of the heterologous M types. Ribosomes isolated by either method were found to be contaminated with cell surface proteins. Chemical analysis of the ribosomes showed a greater protein:ribonucleic acid ratio in ribosomes from physically disrupted cells than in ribosomes from enzymatically disrupted cells (2:1 versus 1:1). Antisera to ribosomes isolated from physically disrupted cells detected many more antigenic determinants on ribosomes isolated from enzymatically disrupted cells than did the corresponding homologous antisera. Immunodiffusion analysis suggested that ribosomes isolated from physically disrupted cells may contain cell wall antigenic determinants which are present on ribosomes isolated from enzymatically disrupted cells in a partially degraded form. Washing of ribosomes in high-molarity salt solutions suggested that some of the contaminating cell wall proteins are tightly bound to the ribosomes.

Experimental sporotrichosis in Syrian hamsters

Syrian hamsters were infected with Sporothrix schenckii by subcutaneous footpad inoculation. Two types of infection could be uniformly induced: a self-limited, lymphatic infection resembling the classical disease in humans, and a generalized nonfatal infection. An infecting dose of approximately 5,300 yeast cells produced the localized subcutaneous-lymphatic disease which was limited to a single limb. In contrast, a 1,000-fold increase in the inoculum temporarily overwhelmed the animals' defense mechanisms, producing a systemic infection involving the liver and spleen. These models were used to demonstrate the development of increased resistance to subsequent infection following either infection or active immunization with ribosomal fractions or trypsinized cell wall antigens of S. schenckii incorporated in Freund complete adjuvant. Agglutination titers were detectable in all animals that were either infected or immunized. In one group of infected animals, the titers persisted for at least 1 year after three booster doses of Formalin-killed S. schenckii. The ability to produce an infection in hamsters which closely resembles the disease seen in humans makes the animal a good model with which to study experimental sporotrichosis.

Immunogenic capacity of ribosomes of Salmonella typhi interfered with a flagellin-like material contaminant

The double-immunodiffusion technique and sodium dodecyl sulfate-polyacrylamide electrophoresis were used to demonstrate the presence of flagellin-like material strongly attached to ribosomes of Salmonella typhi Ty 2. This flagellin-like material contaminating the ribosome preparation interferes with the induction of antiribosome serum promoting the formation of antisera reacting either only with flagellin or in some cases with flagellin and ribosomes, but giving a very weak reaction with the latter. The interference is also observed when purified ribosomes from a nonflagellated mutant of S. typhi (S. typhi O-901) mixed with purified S. typhi Ty 2 flagellin are utilized as antigens. The antiribosome sera obtained with ribosomes from S. typhi O-901 have a considerably higher titer than those that are interfered with. These sera were able to react with ribosomes obtained from several related species and did not react with flagella-derived flagellin of S. typhi Ty 2.

Characterization of the immunoprotective antigen of ribosomal preparations from Haemophilus influenzae

This investigation was designed to characterize the immunoprotective antigen of ribosomal preparations from Haemophilus influenzae. The ribosomes that elicited 80 to 90% protection contained 25% protein and 75% ribonucleic acid but did not contain any detectable hexoses. The immunodiffusion and hemagglutination inhibition tests also failed to demonstrate that the capsular material (polyribose phosphate) was in ribosomal preparations. Treatment of ribosomes with ribonuclease degraded 78% ribonucleic acid but did not affect the immunogenicity of such preparations. The proteolytic enzymes reduced the immunogenicity of ribosomes corresponding to the amount of protein degraded. The protection elicited by ribosomal protein extracted with 2-chloroethanol was comparable to that induced by intact ribosomes. In contrast, the low levels of protection observed by immunization with phenol-extracted ribonucleic acid were dependent on the amounts of contaminating protein. Finally, immunogenicity of ribosomal ribonucleic acid and protein was abrogated by treatment with proteolytic enzymes. These results clearly indicate that the protein associated with Haemophilus ribosomes is the major immunoprotective antigen.

Lack of protection afforded by ribonucleic acid preparations from Mycobacterium tuberculosis against Mycobacterium leprae infections in mice

Mycobacterial ribonucleic acid preparations from H37Ra, an attenuated strain of Mycobacterium tuberculosis, provide their usual marked protection against M. tuberculosis challenge; however, they provided no protection against Mycobacterium leprae challenge. Suspensions of intact H37Ra were not effective against M. leprae. Suspensions of BCG gave their usual distinct protection against M. leprae challenge.

Adoptive transfer of immunity from mice immunized with ribosomes or live yeast cells of Histoplasma capsulatum

This investigation was designed to compare the role of lymphoid cells and immune serum in protective immunity induced by immunization with ribosomes or live yeast cells of Histoplasma capsulatum. Spleen cells, peritoneal cells, and serum from C3H mice immunized with Histoplasma ribosomes or live cells were transferred intravenously to separate groups of syngeneic recipients. All recipients along with a set of immunized and control mice were challenged intravenously with 4 x 10(6) yeast cells of H. capsulatum, and protection was assessed. Immunization with ribosomes or live cells provided 90 to 100% protection. Mice receiving filtered spleen cells or peritoneal cells from donors immunnized with live cells showed 90 to 100% protection; 80 to 90% protection was observed for mice receiving cells from ribosome-immunized donors. In contrast, no evidence of protection was seen in mice receiving serum from either live-cell- or ribosome-immunized mice. Peritoneal cells were far more efficient than spleen cells in adoptive transfer of immunity. The adoptive immunity in recipients persisted for at least 3 weeks after transfer, the longest period tested in the present study. These results indicate that the immunity elicited by immunization with Histoplasma ribosomes or live cells is mediated by a cellular mechanism.

Immunoprotective activity of ribosomes from Haemophilus influenzae

Immunization with ribosomal preparations from Haemophilus influenzae type b elicited protective immunity in mice. Ribosomes from disrupted cells where isolated by differential centrifugation using sodium dodecyl sulfate. The washed ribosomes contained 25% protein and 75% ribonucleic acid and sedimented as a single peak on sucrose density gradient analysis with a sedimentation coefficient of 67S, using Escherichia coli ribosomes as a 70S marker. Immunodiffusion tests with antipolyribose phosphate serum showed that the ribosomes were free from capsular material. Mice immunized subcutaneously with ribosomes, with or without adjuvant, were challenged intraperitoneally with 100 to 1,000 mean lethal doses of H. influenzae type b suspended in gastric mucin. Significant protection was induced by ribosomes and was compared to that obtained after sublethal infection with live cells. The protection was greatly enhanced after incorporation of ribosomes into adjuvants. Maximum protection (90 to 95%) was observed at 1 to 2 weeks after immunization. Ribosomes from a nonencapsulated strain of H. influenzae were as immunogenic as those from the encapsulated strain, demonstrating that the capsular material is not responsible for immunogenicity of Haemophilus ribosomes.

Immunogenic activity of a ribosomal fraction obtained from Pasteurella multocida

The cells of P. multocida strain P-1059 were destroyed with the French pressure cell; the ribosomal fraction proven to be homogeneous by analytical ultracentrifugation was obtained from the product by centrifugal fractionation, zonal electrophoresis, and Sephadex G-200 gel filtration. The ribosomal fraction exhibited intense protective antigenicity in mice and chickens, but the lipopolysaccharide (endotoxin) and the other bacterial cell fraction obtained in this experiment did not. Sodium deoxycholate treatment of the ribosomal fraction resulted in only a 13% loss in immunological activity, and ribonuclease treatment caused a 60% loss of activity.

Effect of the injection of ribosomes and RNA from Crithidia fasciculata on the experimental infection of mice by Trypanosoma cruzi

Immunization of mice with Crithidia fasciculata (live suspension, ribosomal fraction and purified RNA) induced a certain degree of protection (decrease of parasitaemia) against infection with Trypanosoma cruzi.

Mycobacterial ribonucleic acid: comparison with mycobacterial cell wall fractions for regression of murine tumor growth

Mycobacterial ribonucleic acid (RNA) and cell wall skeleton fraction isolated from H37Ra caused P-815 mastocytoma regression in DBA/2 mice provided the animals were presensitized with freshly harvested living H37Ra cells. In the absence of presensitization, only the RNA fraction inhibited. Cell wall skeleton fraction, under these conditions, stimulated tumor growth. Cell wall lipids (from H37Ra) added to H37Ra cell wall skeleton fraction did not increase the inhibitory activity of cell wall skeleton fraction alone. Mycobacterial RNA appeared to be an effective inhibitor of P-815 mastocytoma metastases as shown by (i) the inhibition of a second footpad lesion distant from the one treated and (ii) increase in survival time.

Variability of protection in inbred mice induced by a ribosomal vaccine prepared from Salmonella typhimurium

Ribosomal vaccines prepared from Salmonella typhimurium were effective immunogens in A/J inbred mice and C3H/HeTex, inbred mice. However, ribosomal vaccines were not protective in C57BL/6J inbred mice. A/J mice were protected against lethal challenge by attenuated S. typhimurium live-cell, ribosomal, phenol, and heat-killed vaccines. C3H/HeTex mice were protected by live-cell, ribosomal, and phenol vaccines but not the heat-killed vaccine. Only the live-cell vaccine gave significant protection in the C57BL/6J inbred mice. A comparison of the kinetics of infection in sham-immunized mice and mice immunized with ribosomes showed that ribosome preparations elicited protection against Salmonella infection in mice inherently sensitive and resistant to Salmonella.

Effect of rifampin on immunity to tuberculosis and on delayed hypersensitivity to purified protein derivative

Mice vaccinated with mycobacterial ribonucleic acid (RNA) produced a high immune response and did not develop delayed hypersensitivity to purified protein derivative (PPD), and rifampin had no effect on the immune response. Mice vaccinated with viable H37Ra cells produced a high immune response and did develop delayed hypersensitivity to PPD. Rifampin had no effect on this immune response, but reduced the footpad reactions to PPD. Both mycobacterial RNA and poly(A:U) served as adjuvants for induction of hypersensitivity to PPD. This hypersensitivity was reduced by the administration of rifampin. Rifampin had no effect on the production of mycobacterial growth inhibitory factor, which is produced following vaccination of mice with mycobacterial RNA or viable H37Ra cells. Rifampin had no effect on the nonspecific phase of the granulomatous response, but did inhibit the secondary allergic phase of this response. The action, therefore, of rifampin that inhibits the induction of delayed hypersensitivity but had no effect on the immune responses against tuberculosis leads to a separation of tuberculin hypersensitivity from cellular immunity to tuberculosis.

Immunogenicity of ribosomal vaccines isolated from group A, type 14 Streptococcus pyogenes

A ribosomal preparation isolated from group A, type 14 Streptococcus pyogenes protected mice against a challenge of 1,000 mean lethal doses. Optimal immunization consisted of subcutaneous administration of 326 mug of protein with Freund incomplete adjuvant. Animals immunized with higher or lower antigen concentrations showed decreased survival. Freund incomplete adjuvant was necessary to insure optimum immunization. Immunochemical studies showed no M protein or C carbohydrate present in the ribosomal preparation. Mice optimally immunized with the type 14 ribosomal preparation were protected against heterologous challenge with M types 2, 5, 8, and 12. Protein-free ribonucleic acid extracts isolated from the type 14 ribosomal preparation did not protect mice against homologous challenge. But ribonucleic acid-free protein extracts showed 100% protection in mice after homologous challenge.

Protection against Toxoplasma gondii in mice immunized with Toxoplasma cell fractions, RNA and synthetic polyribonucleotides

Mice immunized with fractions obtained by centrifugation of disrupted Toxoplasma gondii trophozoites as well as with 200 μg of Toxoplasma ribonucleic acid (RNA) were resistant (as measured by time to death and total mortality) to challenge with Toxoplasma 30 days later. When mice were challenged at 15 days no protection was noted. A dose of 50 μg of Toxoplasma RNA was effective in protecting mice against lethal challenge only when incorporated into Freund's incomplete adjuvant. In studies performed to determine the specificity of the resistance observed, resistance was also noted in mice immunized with 200 μg of RNA extracted from normal mouse peritoneal macrophages, as well as in mice immunized with 100 μg of the synthetic polyribonucleotide polycytidylic acid. Polyadenylicuridylic acid conferred protection only when incorporated into Freund's incomplete adjuvant and polyinosinic—cytidylic acid had no effect. The protection induced by Toxoplasma RNA was eliminated by prior treatment of the preparation with ribonuclease but not by treatment with pronase, suggesting that the moiety responsible for the protective effect was RNA. In experiments designed to explore the mechanism of resistance in the vaccinated mice, macrophages harvested from mice which had been injected with Toxoplasma RNA 15 days earlier were found to be activated in that they resisted challenge with Listeria monocytogenes.

Ribosomal vaccines. II. Specificity of the immune response to ribosomal ribonucleic acid and protein isolated from Salmonella typhimurium

Ribosomal proteins isolated from Salmonella typhimurium were effective in inducing immunity in mice. This immunity was specific since animals immunized with ribosomal proteins from S. typhimurium were not protected against challenge with S. cholerae-suis or S. enteritidis. Immunity was evident as early as 5 days after immunization. Ribosomal ribonucleic acid (RNA) failed to provide any effective immunity in mice. Polyinosinic acid: polycytidylic acid (poly I: C) induced a rapid, short-lived immunity to all three Salmonella species. In contrast, ribosomal RNA failed to elicit any rapid nonspecific response to infection.

Ribosomes of acid-fast bacilli: immunogenicity, serology, and in vitro correlates of delayed hypersensitivity

Ribosomal fractions obtained from Mycobacterium bovis (BCG) and M. smegmatis (strain butyricum) were studied to determine their antigenicity, their ability to stimulate the production of soluble mediators of delayed hypersensitivity (in vitro correlates) by sensitized peritoneal exudate cells, and the antigenic relations of ribosomal antigens of BCG to BCG protoplasm and H37Rv culture filtrates. The crude ribosomes and the 50-30S ribosomal subunit pool obtained from each of the organisms induced both delayed and immediate hypersensitivity when injected in incomplete Freund adjuvant into rabbits, and skin reactions could be elicited in sensitized rabbits with those antigens. The crude ribosomes and 50-30S ribosomal subunit pool of M. smegmatis stimulated lymphocytes of guinea pigs sensitized with viable organisms to produce macrophage migration inhibition factor. Comparable ribosomal fractions from BCG bacilli caused lymphocytes of guinea pigs sensitized with viable M. bovis (BCG) to produce skin reactive factor. Immunoelectrophoretic studies showed that H37Rv culture filtrate, protoplasm, crude ribosomes, and 50-30S ribosomal subunits of BCG contain multiple precipitinogens and that many of these were shared between the different antigen systems. Comparative electrophoresis revealed that BCG protoplasm and H37Rv culture filtrate shared a major portion of their components with each other and relatively few with ribosomal systems. The ribosomal systems shared the major portion of their components with each other and relatively few with the other antigen systems.

Relationship between tuberculin hypersensitivity and cellular immunity to infection in mice vaccinated with viable attenuated Mycobacterial cells or with Mycobacterial ribonucleic acid preparations

The migration inhibition technique has been used to study delayed hypersensitivity in vitro by using peritoneal exudate cells and splenic lymphocytes from mice vaccinated with viable cells of the attenuated H37Ra strain of Mycobacterium tuberculosis and from mice vaccinated with ribonucleic acid (myc RNA) preparations obtained from viable mycobacterial cells of the same strain. Inhibition of macrophage migration was noted when purified protein derivative (PPD) or viable H37Ra cells were added to peritoneal exudate cells obtained from mice immunized with viable H37Ra cells and not from mice immunized with myc RNA. Splenic lymphocyte cultures were exposed to the same antigens in vitro. Filtered supernatant fluids from these lymphocyte cultures, when added to peritoneal exudate cells obtained from nonimmunized mice, inhibited migration only when they were obtained from lymphocytes which came from mice immunized with viable H37Ra cells. Injection of PPD intravenously into vaccinated mice resulted in inhibitory supernatant fluids from splenic lymphocyte cultures only when the lymphocytes came from mice immunized with viable H37Ra cells. However, intravenous injection of either viable H37Ra cells or of myc RNA preparations into mice vaccinated with myc RNA occasionally produced inhibitory supernatant fluids when lymphocytes were obtained from these mice. On the other hand, mice vaccinated with myc RNA or viable H37Ra cell preparations were consistently and equally protected against intravenous challenge with the virulent H37Rv strain. Thus, although some evidence was obtained for a delayed type hypersensitivity in mice vaccinated with H37Ra cells or with myc RNA to ribosomal proteins or other proteins associated with the RNA preparation, no evidence of tuberculin hypersensitivity could be detected in any mice vaccinated with the myc RNA. These results argue against a role for tuberculin hypersensitivity in immunity to tuberculous infection.

Immunity to Salmonella typhimurium infection: characterization of antigens in active protection by polyacrylamide gel electrophoresis

Immunity to challenge with Salmonella typhimurium (strain SR-11) was studied in NIH/NMRI Swiss mice. Viable organisms induced the best protection, but ribosomes were the best immunogen of the subcellular fractions. Antigens with lower concentrations of protein did not induce protection as well as antigens which had higher concentrations of protein. Acrylamide gel electrophoresis of the SR-11 subcellular components, fractionation, and differential staining of the gel columns indicated that the immunogen is a high-molecular-weight glycoprotein or mucopolysaccharide.

Effect of polybasic amines on the immunogenicity of mycobacterial ribonucleic acid

The five polybasic amines, methylated bovine serum albumin (MBSA), protamine sulfate, neomycin sulfate, streptomycin sulfate, and diethylaminoethyl-dextran (DEAE-dextran), were examined to determine their effects on the immunogenic activity of mycobacterial ribonucleic acid (RNA) preparations, and whether they could substitute for Freund incomplete adjuvant (FIA) by protecting the mycobacterial RNA in vivo. These compounds were either emulsified in FIA or not emulsified in FIA. Different results were obtained when these compounds, complexed with mycobacterial RNA, were emulsified in FIA. MBSA, in ratios of mycobacterial RNA-MBSA of 1:0.2 to 1:0.4, had no effect on immunogenic activity. However, when the ratio was increased to 1:1, 1:2, or to 1:4, marked inhibition of the immunogenic activity occurred. Protamine sulfate and neomycin sulfate also inhibited the immunogenic activity of mycobacterial RNA; however, neither streptomycin sulfate nor DEAE-dextran had any effect on immunogenic activity. Without being emulsified in FIA, these five polybasic amines, with the exception of DEAE-dextran, acted only as weak adjuvants for mycobacterial RNA and, therefore, could not be used as substitutes for FIA for the protection of mycobacterial RNA from host nucleases. DEAE-dextran, although not as effective as FIA, afforded some protection for the mycobacterial RNA. DEAE-dextran alone also produced a low degree of nonspecific immunity against tuberculosis. Since MBSA, protamine sulfate, and neomycin sulfate reduce the biological activity of mycobacterial RNA after complexing with it, it is probable that these compounds "mask" the immunogenic sites on the mycobacterial RNA structure.

Response of vaccinated and nonvaccinated syngeneic C57B1-6 mice to infection with Mycobacterium tuberculosis

Data are presented which show that the syngeneic C57B1/6 mouse strain is far more susceptible to infection with Mycobacterium tuberculosis strain H37Rv than are the other allogeneic mouse strains used in this laboratory, particularly the Strong A and the CF-1 strains. Not only are the C57B1/6 mice more susceptible to tuberculous infection, but also they respond to infection more uniformly than do the allogeneic strains. C57B1/6 mice develop immunity to challenge with small infecting doses of the virulent H37Rv strain when they are vaccinated with viable cells of the attenuated H37Ra strain and with ribonucleic acid (RNA) preparations isolated from the H37Ra strain. Mice vaccinated with viable cells of the H37Ra strain, however, may die more rapidly than nonvaccinated mice when given a large infecting dose (1.0 mg). This accelerated type of disease is not seen in mice vaccinated with mycobacterial RNA. Since C57B1/6 mice are known to develop tuberculin hypersensitivity more readily than many other mouse strains, the possibility is discussed that the increased susceptibility to tuberculous infection of mice vaccinated with viable cells of the H37Ra strain may be due to a superimposition of a pronounced acute inflammatory response due to tuberculin hypersensitivity upon the infectious process. The several advantages that may be gained in the study of certain host-parasite interactions in tuberculosis by the use of a highly susceptible syngeneic mouse strain such as the C57B1/6 are discussed.

Delayed hypersensitivity reactions provoked by ribosomes from acid-fast bacilli. I. Ribosomal isolation, characterization, delayed hypersensitivity, and specificity

Ribosomes and ribosomal subunits of Mycobacterium bovis (strain BCG) and M. smegmatis have been isolated and employed as skin test antigens in guinea pigs sensitized with homologous or heterologous organisms. Ribosomes and ribosomal subunits were found to be potent antigens for skin test purposes, and the 30S subunits were found to be more specific and active than the 50S subunits.

Response of mice to injection of ribosomal fraction from group B Neisseria meningitidis

Ribosomes of strain NOR-7 of group B Neisseria meningitidis were isolated by a procedure that included treatment of the cells with sodium dodecyl sulfate, disruption in a French pressure cell, and differential centrifugation. These preparations consisted of 66% ribonucleic acid and 24% protein and sedimented as a single component with a constant of approximately 66S. When used in immunodiffusion tests with homologous rabbit antiserum, untreated ribosomes formed two precipitin lines, when treated with ribonuclease three lines, and when Pronase-digested only one distinct line. Qualitatively indistinguishable reactions were obtained with the same antiserum and ribosomes from group A meningococci, but no precipitation occurred with those of Escherichia coli. When injected into mice, group B ribosomes elicited an increase in the number of antibody-producing spleen cells demonstrable by the hemolytic plaque technique using unsensitized sheep erythrocytes. Sensitization of the erythrocytes with increasing amounts of supernatant fluid of meningococcal cultures progressively reduced the number of demonstrable plaque-forming cells. Neuraminidase treatment of the erythrocytes increased immune hemolysis, whereas Pronase digestion reduced it. Injected mice were protected against homologous and heterologous meningococcal challenge. Both hemolysis and protection-inducing activities of the ribosomes were unimpaired by ribonuclease, but were reduced by Pronase. It is concluded that the immunological response elicited by the meningococcal ribosomes does not involve the group-specific carbohydrate antigen. The immunological mechanism by which the mice are protected against meningococcal challenge remains unknown.

Isolation of protective somatic antigen from Vibrio cholerae (Ogawa) ribosomal preparations

Ribosomal preparations from Vibrio cholerae Ogawa and Inaba are protective immunogens for mice challenged with either serotype. Column chromatography of ribosomal fractions separated protective antigen from the ribosomes. The antigen is a heterogeneous colloid which contains protein, lipid, and carbohydrate in the ratio 3:1:1. Amino acid composition is that of a slightly acidic protein with no unusual complement of amino acids. The lipid component consists of several longchain fatty acids and of phosphatidyl ethanolamine. The major sugars identified were glucose and galactose. The colloid can be dissolved by treatment with chelating agents and sodium dodecyl sulfate. Purification of the solubilized material or of the colloid was unsuccessful.

Ribosomal vaccines. I. Immunogenicity of ribosomal fractions isolated from Salmonella typhimurium and Yersinia pestis

The immunogenicity of ribosomes and ribosomal subfractions isolated from Yersina pestis and Salmonella typhimurium has been studied. Ribosomes and ribosomal protein isolated from S. typhimurium protected mice against lethal challenge. Ribosomal ribonucleic acid isolated by phenol extraction failed to induce any significant level of protection in mice. None of the ribosomes or ribosomal subfractions isolated from Y. pestis were effective in inducing immunity to lethal challenge. These results suggest that the immunogen of the ribosomal vaccine is protein.

Staphylococcidal capability of rabbit peritoneal macrophages in relation to infection and elicitation: delayed-type hypersensitivity without increased resistance

The staphylococcidal capability of populations of peritoneal macrophages in rabbits has been measured before and after repeated infections with Staphylococcus aureus. Such rabbits after infection showed delayed-type hypersensitivity to S. aureus antigens, but the staphylococcidal capability of the peritoneal macrophages was not increased. This result at the cellular level is in agreement with previous assessment in vivo of the consequences of staphylococcal infection. Pathways to cell-mediated resistance, with and without delayed-type hypersensitivity, are presented.

Purification of immunogenically active ribonucleic acid preparations of Salmonella typhimurium: molecular-sieve and anion-exchange chromatography

Immunogenic Salmonella typhimurium ribonucleic acid (RNA) preparations, prepared by differential centrifugation, phenol extraction at 65 C, and ethanol precipitation from 0.5% sodium dodecyl sulfate solution, maintained their immunogenicity through lyophilization. As measured by survival, differential pathogen counts 5 days postchallenge, or clearance of the infecting organism from the tissues, immunization with 50 mug (dry weight) of the lyophilized preparation proved as effective as immunization with 0.1 LD(50) of attenuated S. typhimurium cells. Chromatography of the immunogenic fraction through Biogel P-6 (exclusion limit > 4,600) or through Biogel P-300 (exclusion limit > 300,000) resulted in only one immunogenically active protein of the eluate found in the void volume of the columns. Diethylaminoethyl (DEAE) cellulose anion-exchange chromatography of the RNA preparations showed that the immunogenic activity was eluted from the column at 0.8 to 1.0 m NaCl in a linear 0.1 to 2.0 m NaCl gradient. Nonimmunogenic, protein-containing minor peaks were eluted at 0.1 to 0.5 m NaCl. Serial fractionation of the crude RNA preparations over Biogel P-6 to DEAE cellulose to Biogel P-300 molecular-sieve or anion-exchange columns did not alter the immunogenicity of the RNA preparation. Incorporation of the column fractions into Freund's incomplete adjuvant did not increase their relative effectiveness in eliciting anti-salmonella resistance. Chemical analysis of the immunogenic preparations indicated that they were lacking in detectable protein, lipid, and deoxyribonucleic acid. These results suggest that the immunogenic moiety of the crude nucleic acid fraction is either RNA or an as yet undefined polysaccharide of greater than 300,000 molecular weight.