Conserved machinery of the bacterial flagellar motor

Novel periplasmic and cytoplasmic structural modules of the bases of bacterial flagella have been observed in situ and isolated using new biochemical protocols. Flagellar rotation may depend upon interactions of these modules with the intramembrane particle rings, a ubiquitous feature of flagellar bases necessary for torque generation. The outer membrane-associated basal disk of the Wolinella succinogenes polar flagellum has architecture well suited for interaction with the ring particles. However, antibody against the main W. succinogenes basal disk protein did not cross-react with flagella-enriched fractions from Salmonella typhimurium and Bacillus firmus; nor have such structures been observed in these species thus far. Antibodies against two S. typhimurium proteins, FliG and FliM, known to be involved in motor function and part of the cytoplasmic module in this species cross-reacted with flagella-enriched fractions from both W. succinogenes and B. firmus. In addition, flagellar cytoplasmic structure could be isolated from B. firmus. The basal disk may anchor the flagellar motor to the cell wall in some polar bacteria, but this does not seem to be a unique strategy. In contrast, the data indicate that the cytoplasmic module is conserved.

Structural characteristics of polysaccharides that induce protection against intra-abdominal abscess formation

Bacteroides fragilis is the anaerobe most commonly isolated from clinical cases of intra-abdominal sepsis. In a rodent model of this disease process, intraperitoneal injection of the capsular polysaccharide complex (CPC) from B. fragilis provokes abscess formation, while subcutaneous administration of this complex confers protection against B. fragilis-induced intra-abdominal abscesses. The CPC consists of two discrete polysaccharides, polysaccharides A and B (PS A and PS B), each possessing oppositely charged structural groups critical to the ability of these carbohydrates to induce the formation of abscesses. Other bacterial polysaccharides that possess oppositely charged groups (such as the group antigen or capsular polysaccharide from Streptococcus pneumoniae type 1 strains) also exhibited potent abscess-inducing capabilities. We report here that positively and negatively charged groups on polysaccharides are also essential for inducing protection against abscess formation. Vaccination of rats with B. fragilis PS A, PS B, or the S. pneumoniae type 1 capsule protected against intra-abdominal abscesses subsequent to intraperitoneal challenge with each of these polysaccharides. Chemical conversion of the free amino or carboxyl groups on PS A to uncharged N-acetyl or hydroxymethyl groups, respectively, abrogated the ability of this polymer to confer protection against polysaccharide-mediated abscess formation. Adoptive transfer of splenic T cells from polysaccharide-vaccinated rats to naive animals demonstrated that T cells mediated this protective activity. T cells transferred from animals vaccinated with a polysaccharide repeating unit (Salmonella typhi Vi antigen) that normally contains one carboxyl group but was chemically converted to a polymer that possesses both free amino and carboxyl groups (accomplished by de-N-acetylating the Vi antigen) protected naive T-cell recipients against polysaccharide-induced abscesses. These results demonstrate that a distinct structural motif associated with the B. fragilis polysaccharides is necessary for induction of protective immunity against abscess formation associated with intra-abdominal sepsis. However, protection is not antigen specific in a traditional sense. Rather, the protective ability of these structurally dissimilar polysaccharides is conferred by, and perhaps specific for, a motif of oppositely charged groups.

Resistance to infection and activation of the monocyto-macrophage system caused by Bacillus firmus and its fractions

Crude lipids isolated from Bacillus firmus, but not from other bacilli, were previously found to induce significant resistance against Listeria monocytogenes infection in mice. In this study, formaldehyde- and heat-killed bacterins of eight Bacillus species and some cellular fractions of B. firmus were prepared and tested for further immunomodulatory activities. Crude lipids, their aqueous extract, LTA, Protodyne and Pex-residue preparations exhibited a strong anti-infection activity, whereas Pextract, P40 and all bacterins tested had no effect. Formaldehyde-killed bacterins, live bacteria and the P40 preparation of both B. firmus strains, as well as bacterins of both B. subtilis strains, induced pronounced splenomegaly in mice. Peptidoglycan and Pex-residue induced significant depression of cytochrome P-450 in mouse liver microsomes after application of 0.1 mg per mouse. Optimal conditions for obtaining a bacterial suspension exhibiting these immunomodulatory properties were elaborated.

Development of a monoclonal antibody-based competitive inhibition enzyme-linked immunosorbent assay for detection of Bacillus piliformis isolate-specific antibodies in laboratory animals

A competitive inhibition enzyme-linked immunosorbent assay (ELISA) was developed to detect Bacillus piliformis isolate-specific antibodies in serum specimens from rats and gerbils experimentally infected with B. piliformis isolates R1, R2, or M. Detection was based on the ability of serum antibodies to block binding of B. piliformis isolate-specific monoclonal antibodies to purified B. piliformis flagella. Application of this assay to serum specimens collected from sham-infected or experimentally infected rats and gerbils demonstrated that the serum specimens were capable of specifically inhibiting the binding of B. piliformis isolate-specific monoclonal antibodies to homologous flagella preparations (> 70% inhibition) only when the serum specimens were from animals infected with the homologous B. piliformis isolate. Only one false-negative and false-positive result were obtained when 80 serum specimens were tested by this competitive inhibition ELISA. In addition, we demonstrated that little nonspecific inhibition of monoclonal antibody binding occurred (< 30% inhibition) in this immunoassay specific inhibition of monoclonal antibody binding by serum was due to serum antibody and a serum's ability to inhibit binding of monoclonal antibodies to purified B. piliformis flagella was correlated with antibody reactivity with B. piliformis flagella but not with serum antibody reactivity to whole B. piliformis organisms. These results suggest that this monoclonal antibody-based competitive inhibition assay could be successfully applied to the serologic identification of isolates involved in naturally occurring B. piliformis infections in laboratory animals.

Structural and immunological characterization of a biosurfactant produced by Bacillus licheniformis JF-2

Bacillus licheniformis JF-2 produces a very active biosurfactant under both aerobic and anaerobic conditions. We purified the surface-active compound to homogeneity by reverse-phase C18 high-performance liquid chromatography and showed that it is a lipopeptide with a molecular weight of 1,035. Amino acid analysis, fast atom mass and infrared spectroscopy, and, finally, 1H, 13C, and two-dimensional nuclear magnetic resonance demonstrated that the biosurfactant consists of a heterogeneous C15 fatty acid tail linked to a peptide moiety very similar to that of surfactin, a lipopeptide produced by Bacillus subtilis. Polyclonal antibodies were raised against surfactin and shown to exhibit identical reactivity towards purified JF-2 lipopeptide in competition enzyme-linked immunosorbent assays, thus providing further evidence for the structural similarity of these two compounds. Under optimal conditions, the B. licheniformis JF-2 biosurfactant exhibits a critical micelle concentration of 10 mg/liter and reduces the interfacial tension against decane to 6 x 10(-3) dyne/cm, which is one of the lowest interfacial tensions ever reported for a microbial surfactant.

Role of the integument in insect immunity: epicuticular abrasion and induction of cecropin synthesis in cuticular epithelial cells

When the epicuticle of a silkworm larva, Bombyx mori, was lightly abraded in the presence of live Bacillus licheniformis, Enterobacter cloacae, or bacterial cell wall components, cecropin mRNAs were detected in the underlying epithelial cells and in fat body cells remote from the abraded area. Antibacterial activity due to cecropin was detected in the matrix of the lightly abraded cuticle but not in nonabraded portions of the cuticular matrix or in the hemolymph surrounding the fat body, unless a more severe cuticular abrasion was administered. A light abrasion to a larva of the giant silkworm moth, Hyalophora cecropia, in the presence of E. cloacae also induced antibacterial activity in the abraded cuticle. These data illustrate that the ectodermally derived lepidopteran larval integument, when challenged by live bacteria or their cell wall components, mounts an immune response. Hence, the insect exoskeleton, which is often considered as an inert protective armor, is indeed actively participating in defense.

Antigenic diversity in flagellar epitopes among Bacillus piliformis isolates

Monoclonal antibodies (MAbs) were developed to Bacillus piliformis isolate-specific flagellar epitopes and used to group B. piliformis isolates on the basis of epitope expression. BALB/c mice immunised with flagella purified from various B. piliformis isolates served as the source of immune spleen cells for fusion with SP2/0Ag14 myeloma cells. Evaluation of hybridoma culture medium by ELISA against various bacterial species and B. piliformis isolates indicated that 482 of 2127 hybridomas secreted antibodies specific for B. piliformis. Specificity of MAbs for flagellar epitopes was demonstrated by indirect fluorescent antibody assays and Western blot analyses. Probing of 10 B. piliformis isolates with MAbs indicated that four B. piliformis isolates each possessed a distinct and isolate-specific flagellar epitope; five other isolates shared a common flagellar epitope. One isolate did not react with any of the MAbs specific for flagellar epitopes. Thus, B. piliformis isolates could be grouped into six antigenically distinct groups based upon flagellar epitope expression. Additionally, a MAb reactive with a cell-associated component recognised all but one isolate. This serological grouping of B. piliformis isolates agrees with the grouping of isolates based upon genetic and physiological characteristics, and supports the assertion that there are different strains among B. piliformis isolates.

Effect of crude bacterial lipids on the course of Listeria infection in mice

Crude lipids from 37 strains belonging to 32 bacterial species were isolated. By injecting mice with lipids 5 d prior to challenge with a virulent strain of Listeria monocytogenes, immunostimulatory activity in 19 preparations was found. In general, lipids of Gram-negative bacteria appeared to be more effective. As to bacilli, an extraordinary activity was found in the lipids of Bacillus firmus. Lipids of various species of the genus Listeria were found to be active in approximately one-half of cases. Among other Gram-positive bacteria, significant activity of lipids was found in Corynebacterium xerosis, Propionibacterium acnes and BCG. The composition of fatty acids in the lipids did not differ significantly from that reported in the literature and their mutual differences could not explain the different biological activity. In selected strains of Gram-negative bacteria lipids were repeatedly purified with anhydrous chloroform; these preparations were found to be inactive as compared with original chloroform-methanol lipids.

Rederivation of rat colonies seropositive for Bacillus piliformis and the subsequent screening for antibodies

Latent infection of rats in a breeding colony with Bacillus piliformis detectable by antibodies to the agent in an immunofluorescence assay was eliminated by a combination of traditional rederivation techniques, using animal units not previously used for rat breeding, and the use of specific disinfection procedures. The success rate was apparently correlated with the use of peracetic acid instead of aldehyde products to decontaminate the animal unit.

Correlation between megaloileitis and antibodies to Bacillus piliformis in laboratory rat colonies

Rat colonies in which antibodies to Bacillus piliformis were detected in animals examined at the age of 8 to 15 weeks were compared with rat colonies where no such antibodies were present. The seropositive colonies had a low incidence of megaloileitis in 5-week-old rats of Sprague-Dawley stock and some few inbred strains. In seronegative colonies, no megaloileitis was detected. In rats with megaloileitis, significantly high titers to B. piliformis were noted and the agents could be identified in the ileal mucosa by immunofluorescence technique.

Scanning force microscopy studies of the S-layers from Bacillus coagulans E38-66, Bacillus sphaericus CCM2177 and of an antibody binding process

In many prokaryotic cells (eubacteria and archaebacteria) the outermost cell envelope component is composed of a regularly structured protein surface layer (S-layer). The two-dimensional S-layer from Bacillus coagulans E38-66 and Bacillus sphaericus CCM2177 has been investigated by SFM at molecular resolution under physiological conditions (i.e., in buffer solution). We find the E38-66 S-layer lattice to be oblique with lattice parameters of a = 9-10 nm, b = 7-8 nm and gamma = 80 degrees -90 degrees (E38-66). The CCM2177 lattice is square with a = 12-14 nm, in good agreement with TEM data. We have used the unique possibility of the SFM to study the kinematics of biological processes and have performed experiments on the adhesion of polyclonal antibodies to the recrystallized E38-66 protein layer on a time scale of about two to ten seconds per image frame. This represents a first step in directly visualizing molecular recognition reactions.

Bacillus piliformis flagellar antigens for serodiagnosis of Tyzzer's disease

Purified flagella from multiple isolates of Bacillus piliformis were obtained and examined by electron microscopy. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and Western blot (immunoblot) analyses were used to assess the purity, antigenicity, and cross-reactivity of purified flagellar preparations. SDS-PAGE demonstrated a single, major protein band evident at approximately 53 to 56 kDa in all isolates tested. Results of Western blot analyses indicated a lack of cross-reactivity between flagellar antigens and heterologous isolates. Enzyme-linked immunosorbent assays (ELISAs) were used to compare the efficacies of flagellar preparations from the various isolates as antigens in detecting B. piliformis serum antibodies from several host species. ELISA results indicated that no single flagellar preparation could be relied on to consistently identify serum antibodies in all the host species tested; however, ELISAs that utilized a trivalent flagellar antigen preparation were shown to be specific and sensitive for the detection of antibodies to B. piliformis.

A serological survey on Bacillus piliformis infection in laboratory rabbits in Japan

A total of 544 rabbit sera obtained from 6 commercial breeding facilities and 9 research institutions during 1985-1990 were tested for Bacillus piliformis antibody by an enzyme-linked immunosorbent assay (ELISA) and indirect immunofluorescent antibody test (IFAT). The antibody was detected in 53 (14.2%) rabbits from 3 breeding facilities and 30 (17.4%) rabbits from 6 research institutions, indicating the prevalence of B. piliformis infection among laboratory rabbits in Japan. The overall agreement with ELISA for immune status was 96.9% (527/544) with IFAT. In tests of the ability of ELISA and IFAT to quantitate antibody, a correlation coefficient (r) of 0.86 (P less than 0.01) was obtained by plotting the measured average log of the ELISA titer against the corresponding log of the IFAT titer.

The effect of alpha 2 macroglobulin-proteinase complexes on macrophage Ia expression in vivo

Alpha-2-Macroglobulin (alpha 2M) is a major plasma proteinase inhibitor. It can also regulate the function of cells of the immune system, including macrophage expression of Ia antigens in tissue culture systems. The present work was done to assess the effect of alpha 2M-trypsin complexes (alpha 2M-t) on macrophage Ia expression in vivo. Bacillus Calmette-Guerin-infected mice were injected intraperitoneally with 100nM alpha 2M-t, phosphate buffered saline (PBS), or bovine serum albumin (BSA) in PBS. The peritoneal cells were harvested by lavage from 3 to 6 days after injection. Differential cell counts were performed, and macrophage Ia antigen expression determined by indirect immunofluorescence. Injection of either alpha 2M-t or BSA solutions tended to increase the number of total cells and lymphocytes harvested, without changing the number of macrophages harvested. alpha 2M-t injection reduced the proportion of macrophages which were Ia positive from 60 to 37% on day 3 after injection, and to 20% Ia positive on day 6. The reduction in Ia positive macrophages was statistically significant when compared to either PBS or BSA injected groups. In summary, in vivo exposure to alpha 2M-t can alter macrophage function. alpha 2M-proteinase complexes formed during the course of coagulation or inflammation may play a physiologic role as regulators of the immune response.

Detection of serum antibodies to Bacillus piliformis in mice and rats using an enzyme-linked immunosorbent assay

Rats and mice were infected with Bacillus piliformis organisms at a dosage which resulted in clinical signs of Tyzzer's disease in gerbils. Although rats and mice did not show clinical signs of disease, rising antibody titers to B. piliformis were detected by enzyme-linked immunosorbent assay (ELISA) 2 to 6 weeks post-inoculation and remained at positive levels 11 weeks post-inoculation. Western blot analyses of sera from experimentally infected animals revealed banding patterns nearly identical to those obtained using hyperimmune serum. Results indicated that elevated ELISA titers reflected production of specific antibodies directed against antigens of B. piliformis. ELISA and Western blot analyses of naturally infected animals yielded similar results. These findings suggest that immunoassays such as ELISA can be used to detect subclinically infected rats and mice in the absence of clinical signs or histopathologic evidence of Tyzzer's disease.

Polyvalent interaction of antibodies with bacterial cells

We have studied the physical-chemical characteristics of the interaction of peroxidase-labelled rabbit antibodies with Bacillus sp. bacterial cells. The antibodies are able to bind bivalently with two antigen sites on the bacterial cells with the formation of intramolecular "cyclic" complexes. A kinetic model is proposed suggesting the existence of monovalent and bivalent cell surface antigens. The equilibrium constant of the bivalent IgG binding to the bacterial cell is by two orders of magnitude higher as compared to monovalent Fab fragments. The intramolecular reaction between the free active site of the monovalently bound antibody and a free antigen site on the cell surface is the rate limiting step of the polyvalent interaction. Formation of the cyclic complexes seems to be accompanied by essential tension of bonds and deformation of the IgG molecule. Agglutination of bacterial cells was also studied. The cell agglomerate size dependence on the antibody concn has a threshold. Agglutination proceeds under conditions where the antigen-antibody binding on the cell surface is far from equilibrium.

Protein and antigenic heterogeneity among isolates of Bacillus piliformis

Protein and antigenic heterogeneity among isolates of Bacillus piliformis, the etiologic agent of Tyzzer's disease, were investigated. The seven isolates utilized in this study were originally isolated from naturally infected animals of different animal species and diverse geographical locations. Isolates were propagated in mammalian cell lines, and bacterial extracts were prepared. Protein and antigenic profiles were compared among isolates, using Coomassie blue-stained polyacrylamide gels and Western blot (immunoblot) analyses, respectively. Results showed differences in protein and antigen banding patterns, indicating diversity among isolates. Western blots probed with serum preabsorbed with a heterologous bacterial extract revealed that numerous antigens have different electrophoretic mobilities among isolates but apparently share common epitopes. Immunodominant cross-reactive antigens may be candidate proteins useful for development of improved serologic diagnostic tests, allowing identification of animals infected with a wide range of B. piliformis isolates.

Inhibition of Dermatophilus congolensis by substances produced by bacteria found on the skin

Bacteria, isolated from the skins of clinically normal sheep, were tested for inhibitory activity against Dermatophilus congolensis grown in vitro. Out of 85 bacterial isolates, 19, mainly Bacillus spp., showed zones of inhibition when grown together with D. congolensis. The inhibitory activity was shown to be due to the metabolites released by the bacteria.

Identification of Bacillus anthracis by using monoclonal antibody to cell wall galactose-N-acetylglucosamine polysaccharide

Guanidine extracts of crude Bacillus anthracis cell wall were used to vaccinate BALB/c mice and to develop monoclonal antibody (MAb) to vegetative cell surface antigens. Two hybridomas selected during this study produced immunoglobulin M immunoglobulins, which appear to be directed to an epitope associated with the galactose-N-acetyl-D-glucosamine polysaccharide. Both demonstrated specificity in their binding to purified B. anthracis cell wall, o-stearoyl-polysaccharide conjugates, and intact, nonencapsulated vegetative cells. The interaction of the MAbs with purified polysaccharide was inhibited by 0.5 M galactose and lactose but not by N-acetylglucosamine, glutamate, glycine, or glycerol. Inhibition by glucose or sucrose was approximately 75% of that seen with galactose. Electron microscopy showed that both MAbs interacted with the cell wall of vegetative cells as well as with the cortex of spores. Neither MAb reacted with encapsulated vegetative cells, such as those from infected guinea pigs, nor did they react with intact spores. After conjugation to fluorescein isothiocyanate, the MAbs stained intensely all B. anthracis strains tested, whereas with two exceptions, none of the strains of 20 other Bacillus spp. was stained. The exceptions, strains of Bacillus cereus, could be differentiated from B. anthracis by being beta-hemolytic on blood agar.

Initial phase of infection with Tyzzer's organism in cultured mouse hepatocytes

The initial phase of infection with Tyzzer's organisms in cultured mouse hepatocytes was observed using indirect immunofluorescence (IF) and a plaque assay. The organisms adhered poorly to aldehyde- or acetone-fixed cells, but once adhered to host cells, whether methanol-fixed or unfixed, they were not removed by methanol or acetone. By the IF as well as the plaque assay, both of which discriminated intra- and extracellularly located organisms, the number of cell-associated organisms increased linearly up to 3 h post-inoculation. The number of intra-cellular organisms increased rapidly in the first 1 h, followed by linear increase at a much lower rate. Similar results were obtained by the plaque assay.

Production of Tyzzer's disease in rats by ingestion of bacterial spores

Tyzzer's disease was produced in rats by peroral inoculation with spores of Bacillus piliformis (Tyzzer's organism) of rat origin. After ingestion of 10(6) spores necrotized lesions with intracellular bacterial propagation were seen in the intestines, liver and heart on days 2 to 14 postinoculation (p.i.). A number of B. piliformis were present within enterocytes of the cecum and colon. Infected cells were also seen in the liver, myocardium and intestinal muscle layers on days 3 to 7 p.i. Infective spores were found to be shed in feces during 3 to 10 days p.i.

Enterohepatitis in Mongolian gerbils (Meriones unguiculatus) inoculated perorally with Tyzzer's organism (Bacillus piliformis)

Enterohepatitis was produced in Mongolian gerbils by intragastric inoculation with Tyzzer's organism from natural infection of a gerbil. Death occurred in 50 to 60% animals 5 to 7 days postinoculation (p.i.). On day 3 p.i., when a few necrotic foci appeared in the liver, a large amount of bacterial antigen was present within ileocecal enterocytes and reticuloendothelial cells of the Peyer's patches. Neutrophil and monocyte infiltration was found in the lamina propria. On day 5 or 6 p.i. there was severe necrotizing and hemorrhagic ileotyphlocolitis. Bacterial antigen was abundant within not only enterocytes, but also smooth muscle cells of the ileum and jejunum as well as reticular cells of the mesenteric lymph nodes. On day 7 p.i. the intestinal lesions subsided in the presence of fewer bacteria, while necrotizing hepatitis became well developed. The results indicated that Mongolian gerbils were highly susceptible to the oral route of infection with the Tyzzer's organism.

Serum antibody prevalence for Herpesvirus sylvilagus, Bacillus piliformis and California serogroup arboviruses in cottontail rabbits from Pennsylvania

A serologic survey of 60 eastern cottontail rabbits (Sylvilagus floridanus) from three counties in Pennsylvania was conducted in March 1983. Serum antibody prevalences for Herpesvirus sylvilagus and La Crosse virus (California serogroup) were less than 4%. There was no evidence of previous exposure to either Jamestown Canyon or snowshoe hare viruses (California serogroup). Antibody to trivittatus virus (California serogroup) was found in 60% of the 20 cottontails from York County. No cottontails had antibodies to Bacillus piliformis, the etiologic agent of Tyzzer's disease.

Investigation of spore surface antigens in the genus Bacillus by the use of polyclonal antibodies in immunofluorescence tests

Fluorescein-conjugated rabbit antibodies to formalized spores of Bacillus anthracis were tested against strains of B. anthracis and other Bacillus species in a subjective immunofluorescence test. The lack of reaction of B. anthracis Vollum spores with conjugated antibody raised against B. anthracis Sterne spores indicated that spores of the Vollum strain lacked a major surface antigen present in most of the other anthrax strains tested, including the non-encapsulated strains Sterne and the Soviet ST1, variants cured of the pX01 plasmid that codes for the toxin, and several virulent strains. Four other antibody preparations, raised against B. anthracis Vollum, New Hampshire, Ames and Strain 15, reacted to an approximately similar degree with spores of all four strains and of Sterne, indicating that Vollum has at least one spore antigen in common with these other strains. The anti-Sterne and anti-Vollum conjugates both displayed cross-reactions with spores of strains of B. cereus, B. coagulans, B. subtilis, B. megaterium, B. polymyxa, B. pumilus and B. thuringiensis. Absorption of the anti-anthrax conjugates with B. cereus NCTC 8035 and NCTC 10320 removed all these cross-reactions, demonstrating the existence of spore antigens specific for anthrax.