Evaluation of allergic and serological tests for diagnosing Brucella melitensis infection in sheep

A total of 291 unvaccinated sheep from Brucella melitenesis-infected flocks were examined for delayed-type hypersensitivity (DTH) responses with Brucellergene commercial allergen and with cold saline extract and cytosol from rough B. melitensis 115, and their sera were tested in the rose bengal test (RBT), complement fixation test (CFT), and enzyme-linked immunosorbent assay (ELISA) with lipopolysaccharide. DTH reactions were maximal after 72 h, with no intensity differences among allergens, inoculation sites (eyelid and tail), and doses tested. There were no differences in the results recorded by visual inspection and palpation of inoculation sites, by measuring skin thickness with a caliper, or by microscopic examination of samples taken at necropsy. Six days after DTH testing, energy was observed in 100% of the animals, and 100% reactivity was recovered only after 24 days. All animals were necropsied, and thorough bacteriological searches were performed. The sensitivities found with the 140 animals from which B. melitensis was isolated were ELISA, 100%; DTH, 97.1%; RBT, 92.1%; and CFT, 88.6%. Those results put into question the value of RBT and CFT as screening and confirmatory tests for sheep brucellosis and at least indicate that their standardization should be modified. For 151 tested sheep from which B. melitensis was not isolated, the percentages of positive animals were ELISA, 100%; DTH, 94.0%; RBT, 57.6%; and CFT, 53.6%. All tests were negative for 100 tested sheep from Brucella-free flocks. The different results of bacteriological and immunological tests suggest the usefulness of developing indirect tests able to distinguish truly infected animals from those that have developed an immunological response.

Evaluation of serological tests for diagnosis of Brucella melitensis infection of goats

Five serological assays were evaluated for the diagnosis of brucellosis in goats: the rose bengal test (RBT), complement fixation test (CFT), radial immunodiffusion (RID) with Brucella and Yersinia enterocolitica O:9 polysaccharides, counterimmunoelectrophoresis (CIEP) with cytosol, and enzyme-linked immunosorbent assay (ELISA) with polyclonal and protein G conjugates and smooth lipopolysaccharide (S-LPS), native hapten polysaccharide (NH), or cytosol antigens. For optimal sensitivity, RBT had to be used with sera-antigen at a 3:1 dilution. In the RID test, Brucella melitensis biotype 1 NH could not be replaced by Brucella abortus biotype 1 or Y. enterocolitica 0:9 polysaccharides. In the ELISA, S-LPS and NH gave similar results and the protein G conjugate increased the specificity. With the sera from 55 B. melitensis culture-positive goats, the sensitivity was 100% for RBT, CFT (titer > or = 4), and ELISA with S-LPS or NH; 94% for RID; and 93% for CIEP. All tests were negative (100% specific) when testing the sera from 127 brucella-free goats. Larger discrepancies among the results of the serological tests were obtained with sera from goats of areas where brucellosis is endemic. When the sera of 20 young goats vaccinated subcutaneously (10(9) CFU of B. melitensis Rev 1) and bled 6 months later were examined, the specificities were as follows: NH ELISA, 60%; CFT and S-LPS ELISA, 75%; RBT, 80%; CIEP, 90%; and RID, 94%. With the sera from 10 young goats vaccinated conjunctivally (10(9) CFU of B. melitensis Rev 1) all tests were 100% specific 4 months after vaccination. The proportion of goats giving a positive reaction after vaccination decreased faster in RID than in other tests.

[Permanent venous access through a +portacath reservoir in patients receiving prolonged chemotherapy]

A significant number of oncology patients need intravenous chemotherapy. Peripheral venous access is generally difficult, frequently requiring central venous access. This study reviews the Author's experience with permanent venous portals. A total of 66 patients records, from January 1992 to April 1994, were reviewed. The central venous portals remained in place an average of 272 days. An average of 8 courses of chemotherapy were given through each port. There was no significant difference in the rate of complications secondary to the portal site. The Authors conclude that the placement of permanent venous portals is a safe and reliable chronic venous access in patients with cancer who require intravenous therapy. The rate of serious complication was 3% which is relatively low for these immunosuppressed patients. All venous portals, except one (98.5%) remained functional.

Comparative analysis of Brucella serotype A and M and Yersinia enterocolitica O:9 polysaccharides for serological diagnosis of brucellosis in cattle, sheep, and goats

Hapten polysaccharides of Brucella smooth M and A serotypes were prepared from Brucella sp. and Yersinia enterocolitica O:9 by previously described hydrolytic (O chain) or nonhydrolytic (native hapten [NH]) procedures. The purified polysaccharides differed only in the presence (O chain) or absence (NH) of lipopolysaccharide core sugars. The polysaccharides were compared by reverse radial immunodiffusion for the diagnosis of brucellosis in cattle (Brucella abortus biotype 1 [A serotype] and Brucella melitensis biotype 3 [AM serotype]), sheep (B. melitensis biotypes 1 [M serotype] and 3), and goats (B. melitensis biotype 1). The reverse radial immunodiffusion test with the NH from B. melitensis 16 M (serotype M) showed the highest sensitivity (89.6 to 97.3%), regardless of the host species and the serotype of the infecting Brucella sp. Y. enterocolitica O:9 NH (A serotype) was useful for diagnosing disease in cattle infected with B. abortus biotype 1, but not in cattle infected with B. melitensis biotype 3, sheep, or goats. The different results obtained with the serotype M and A polysaccharides and the sera from animals infected with M, A, and AM serotypes of Brucella spp. showed that in naturally infected animals, a large proportion of the antibodies are directed to or react with a previously defined common epitope(s) (J. T. Douglas and D. A. Palmer, J. Clin. Microbiol. 26:1353-1356, 1988) different from the A or M epitopes. By using the radial immunodiffusion test with B. melitensis 16M NH, it was possible to differentiate infected from vaccinated cattle, sheep, and goats with a sensitivity and specificity similar to that of the complement fixation test.

Factors affecting detection of Brucella melitensis by BACTEC NR730, a nonradiometric system for hemocultures

The detection of Brucella bacteremia by subculture does not always correlate with a positive signal in the BACTEC NR730 nonradiometric system (Becton Dickinson Diagnostic Instrument Systems, Sparks, Md.). The effect of the inoculum size, pH, sodium polyanetholesulfonate, carbon sources (i-erythritol, sodium pyruvate, monosodium glutamate, D-glucose, and L-alanine), and urea in the release of CO2 was evaluated by using the reference strain Brucella melitensis 16M. In standard NR6 vials with or without blood, inocula 5 to 10 times larger (at least 265 CFU per vial) than those usually found in the blood of patients with brucellosis were necessary to produce a positive growth value (GV) in 4 days or less, and similar results were obtained with vials supplemented with the substrates listed above. GVs were consistently lower in vials with sodium polyanetholesulfonate than in vials without this agent. Vials with no blood inoculated with 265 CFU per vial showed turbidity 1 day before GVs became positive, proving that the major limiting detection factor was the low level of release of CO2 and not an inadequate growth medium. In NR6 vials buffered to pH 6.2, GVs became positive faster and were higher than those in standard vials. NR6 vials at pH 6.2 with 0.3% sodium pyruvate yielded a positive GV in the first day of bacterial turbidity.

Brucella group 3 outer membrane proteins contain a heat-modifiable protein

Brucella melitensis and B. ovis outer membrane blebs contained a protein displaying a temperature-dependent molecular mass upshift from 25 kDa to 30 kDa. A fraction of the protein tightly bound to LPS did not show the molecular mass upshift which was also blocked by exposure of the protein to Zwittergent 314. The B. melitensis heat-modifiable protein and Escherichia coli OmpA shared antigenic determinants. These data indicate that the Brucella group 3 outer membrane proteins belonged to the OmpA family of proteins.

Evaluation of whole cell and subcellular vaccines against Brucella ovis in rams

Five antigen preparations from Brucella ovis strain REO 198 were incorporated with the pluronic polymer L-121 and muramyl dipeptide and tested as vaccines against B. ovis infection of rams. The antigenic preparations were: (1) a fraction enriched in outer membrane proteins and rough lipopolysaccharide (hot saline extract, HS); (2) the proteins from HS substantially free of lipopolysaccharide; (3) outer membrane blebs; (4) outer membrane-peptidoglycan complexes extracted with detergent; (5) killed whole cells. The experimental vaccines were compared with two standard vaccines, rough Brucella abortus 45/20 whole killed cells in an oil based adjuvant, and live Brucella melitensis Rev 1. Immunizations with non-living vaccines were performed on two occasions, 18 weeks apart. The rams were challenged with a virulent strain of B. ovis 31 weeks after the second vaccination and slaughtered 15 weeks thereafter. Rates of infection in groups vaccinated with Rev 1 (33%), and HS (40%) were significantly lower (P < 0.005 and P < 0.025, respectively) than that in the non-vaccinated control group (87%). Strain 45/20 was the only other vaccine that conferred a significant level of protection (50%) (P < 0.05). The organ distribution of the infection and the level of colonization of infected organs did not differ significantly between infected animals in the various vaccine groups and those in the unvaccinated control group. No statistically significant relationship was detected between the magnitude of the antibody responses to the HS extract, to outer membrane proteins, or to the rough lipopolysaccharide, and freedom from infection. The results indicate that the HS extract of B. ovis may represent a useful alternative to B. melitensis Rev 1 or B. abortus 45/20 as a vaccine against B. ovis.

The Myf fibrillae of Yersinia enterocolitica

The Myf antigen produced by Yersinia enterocolitica appeared as a proteic polymer composed of 21 kDa subunits. By transposon mutagenesis we isolated Myf-defective mutants. Those allowed us to clone and sequence a 4.4 kb chromosomal locus involved in Myf production. This region was found to contain three genes that we called myfA, myfB and myfC. Genes myfB and myfC encode an assembly machine related to those involved in the synthesis of many fimbriae: MyfB, the putative chaperone, possesses the consensus residues of the PapD family and myfC encodes a putative outer-membrane protein. MyfA, the major subunit, was found to be 44% identical to the pH 6 antigen of Y. pestis. Myf is thus the Y. enterocolitica counterpart of this antigen, but it is by far not so well conserved as the other virulence determinants such as the Yops, suggesting that Myf and pH 6 antigen do not necessarily play the same role in Y. enterocolitica and Y. pestis. The study of the prevalence of myfA in various species of Yersinia revealed that, like the yst enterotoxin gene, its presence is restricted to the pathogenic serotypes of Y. enterocolitica. By immunogold labelling, Myf appeared as a layer of extracellular material extending locally 2 microns from the bacterial surface, indicative of a fibrillar structure.

Differential binding of wild-type and a mutant RepA protein to oriR sequence suggests a model for the initiation of plasmid R1 replication

DNA replication of the enterobacterial plasmid R1 is initiated by RepA protein. We have developed a new procedure for the purification of RepA from inclusion bodies, which involves CHAPS-mediated solubilization. This method has been also used for the thermosensitive mutant protein RepA2623. The nucleoprotein complexes obtained with both proteins and oriR, the origin of replication, are studied in this paper. DNaseI and hydroxyl-radical footprinting suggest the presence in oriR of two sites with different affinity for RepA separated by eight helical turns. The pattern of hypersensitive sites in the footprints indicates that the oriR sequence, when complexed with RepA, is curved. The binding of RepA molecules to oriR is co-operative and this co-operativity is defective in the thermosensitive protein. Band-shift analysis of RepA-oriR complexes revealed the existence of a species with an anomalously high electrophoretic mobility that appears after formation of the first RepA-oriR complex and requires the sequential interaction of RepA with its two distal binding sites. These features lead us to propose that protein-protein interactions between RepA bound to both distal sites could be responsible for oriR looping. This model represents a novel mechanism that results in activation of an origin in a replicon that does not contain iterons.

Platelet alpha 2-adrenoceptor density in pregnancy-induced hypertensive patients: effect of epidural analgesia

OBJECTIVES

Although pregnancy induced hypertension (PIH) is an important and relatively common medical problem, its pathophysiology remains unresolved and the search for a biochemical marker that precedes the hemodynamic abnormalities of PIH continues. Since human platelets contain alpha 2-adrenoceptors, these receptors were measured in women with PIH to determine whether patients with PIH have alpha 2-adrenoceptor abnormalities that might cause or exacerbate the hypertensive process. The effect of epidural analgesia upon blood pressure and its relation to changes in platelet alpha 2-adrenoceptor density were also investigated.

DESIGN

Biochemical measurements and radioligand binding assays in platelets were performed on 33 patients with the criteria for PIH and on 26 healthy pregnant women.

RESULTS

Blood pressure was significantly elevated in hypertensive women when compared with normotensive pregnant women although, in this group, blood pressure returned to normal levels in response to epidural analgesia. In drug-free hypertensive patients, the specific binding of 3H-yohimbine to platelet membranes increased significantly compared with that in control pregnant subjects. In contrast, the dissociation constant was not significantly different in the two groups. Furthermore, alpha 2-adrenoceptor density in the group with PIH returned to normal levels in response to epidural analgesia.

CONCLUSION

Our findings indicate that PIH is characterized by an exaggerated response of platelet alpha 2-adrenoceptor density to a rise in blood pressure and that this alteration could be significant in the pathogenesis of hypertension. Furthermore, human alpha 2-adrenoceptors undergo regulatory mechanisms similar to those recently described for adrenergic receptors in a variety of animal models.

[Isolation of Yersinia enterocolitica 0:8 in Spain]

BACKGROUND

We presented three cases of enterocolitis due to Yersinia enterocolitica 0:8.

METHODS

We use common isolation media, pathogenicity markers and plasmid analysis.

RESULTS

The study of genetic and biochemical characteristics of the strains showed that they belonged to 1B biotype, 0:8 serotype, and that they not carry the virulence plasmid. However, they have pathogenicity markers that were considered typical of highly virulent strains.

SUMMARY

This are the first isolations of this particular serotype in Spain and they showed, as it happens in other European countries, the spread of serotype 0:8 around the world.

[Creutzfeldt-Jakob disease. The first case with histopathological study in Panama]

We studied the clinical and histopathology findings of the first proved case of Creutzfeldt-Jakob disease in Panama. A sixty-five-years-old female patient referred from Santiago de Veraguas was admitted to Santo Tomás Hospital with a progressive clinical picture of dementia, incoordination and generalized myoclonia. The electroencephalogram showed periodic paroxysmal activity. The patient died eight months after initiated the disease. The cerebral histopathologic study was characteristic of Creutzfeldt-Jakob disease: status spongiform, neuronal loss and non-inflammatory gliosis was found.

Genetic and functional analysis of the basic replicon of pPS10, a plasmid specific for Pseudomonas isolated from Pseudomonas syringae patovar savastanoi

The sequence of a 1823 base-pair region containing the replication functions of pPS10, a narrow host-range plasmid isolated from a strain of Pseudomonas savastanoi, is reported. The origin of replication, oriV, or pPS10 is contained in a 535 base-pair fragment of this sequence that can replicate in the presence of trans-acting function(s) of the plasmid. oriV contains four iterons of 22 base-pairs that are preceded by G+C-rich and A+T-rich regions. A dnaA box located adjacent to the repeats of the origin is dispensable but required for efficient replication of pPS10; A and T are equivalent bases at the 5' end of the box. repA, the gene of a trans-acting replication protein of 26,700 Mr has been identified by genetic and functional analysis. repA is adjacent to the origin of replication and is preceded by the consensus sequences of a typical sigma 70 promoter of Escherichia coli. The RepA protein has been identified, using the minicell system of E. coli, as a polypeptide with an apparent molecular mass of 26,000. A minimal pPS10 replicon has been defined to a continuous 1267 base-pair region of pPS10 that includes the oriV and repA sequences.

[Oral infection by Y. enterocolitica 0:8. Studies of immunization in a murine model]

The evaluation and mechanism of protection against Y. enterocolitica O:8 using different immunization schedules. We immunize 3 groups of 20 mice each against an oral lethal dose of Y. enterocolitica O:8 using: 1) whole cells, 2) hyperimmune sera, and 3) LPS and common antigen. Animals immunized using whole live cells that produce common antigen (O:3 +V and IP614) developed the highest degree of protection, with an overall survival rate of 70% and 60% respectively. Similar results were obtained using animals immunized with sera. Animals immunized using LPS and common antigen also were able to control the replication of the infecting strain. Common antigen and antibodies against it did not inhibit adherence not bacterial invasion. However, it seems to be an important protecting factor, that controls the bacterial replication in intestinal lymph tissue. The exact mechanism is currently unknown.

Protection against the lethal effect and arthritogenic capacity of Yersinia enterocolitica serovar O:3 for mice

Protection against the intravenous lethal effect of Yersinia enterocolitica serovar O:3 for mice can be achieved by oral immunization with bacteria expressing the O:3 lipopolysaccharide (LPS). Under similar experimental conditions, Ca(2+)-dependent cells are more protective than their Ca(2+)-independent counterparts, live vaccines are more efficacious than killed ones, and parenteral immunization is more efficient than the oral route. Antibodies induced by enzyme-treated LPS from an O:3 strain are able to mediate protection against challenge with one homologous strain, but they do not prevent induction of arthritis.

[Obtainment of pineapple juice powder by foam-mat drying]

The foam-mat production and stability using pineapple juice concentrate (25, 30 and 40 degrees Brix), adding a surfactants mixture and maltodextrin (DE 10) as co-adjuvant, stirred in a commercial mixer, was studied. Adequate foam formation conditions were as follows: concentrate of 25 degrees Brix using surface active agents (Sorbac 60-Polisorbac 80) 0.285% surface active agent/total solids, HLB = 6, and stirring time, 7 min. The foam was dehydrated in an oven dried with a horizontal air flow circulation set at 60, 70 and 80 degrees C using 3, 5 and 10 mm bed depths. The best conditions were obtained at 60 degrees C and 5 mm bed depth. The product had a particle size of sieve 40-80, and a moisture content of 3%. It was then packaged in multilayer plastic film and stored at environmental conditions. No brown color formation or mold growth was detected during storage. Pineapple juice and a refreshing drink were prepared. The general acceptability in a community indicated that 95% of the population involved accepted the product.

Cloning vectors, derived from a naturally occurring plasmid of Pseudomonas savastanoi, specifically tailored for genetic manipulations in Pseudomonas

A minimal replicon of 1.8 kb isolated from a 10-kb plasmid of Pseudomonas savastanoi, pPS10, has been used to obtain a collection of small vectors specific for Pseudomonas (P. savastanoi, P. aeruginosa and P.putida). In addition, shuttle vectors that can be established both in Pseudomonas and Escherichia coli have been constructed by adding a pMB9 replicon. The vectors permit cloning of DNA fragments generated by a variety of restriction enzymes using different antibiotic resistance markers for selection and offer the possibility to screen recombinants by insertional inactivation. This cloning system can be used to establish recombinant plasmids in Pseudomonas either at low or high copy number. pPS10 derivatives are compatible with other Pseudomonas vectors derived from broad-host-range replicons of the incompatibility groups P1, P4/Q and W. Introduction and expression of the iaaMH operon in a P. savastanoi mutant deficient in the production of indoleacetic acid has been achieved using one of these vectors.

Antibody response to Brucella ovis outer membrane proteins in ovine brucellosis

Hot saline extracts of Brucella ovis were composed of vesicles with outer membrane proteins (OMPs), lipopolysaccharide, and phospholipid as constituents. Extraction with petroleum ether-chloroform-phenol yielded a protein fraction free of detectable lipopolysaccharide, in which group 3 OMPs (28,500 apparent molecular weight [28.5K], 27.0K, and 25.5K) represented 81% of the total. Group 1 OMPs and 67.0K, 22.5K to 21.5K, and 19.5K to 18.0K proteins were also detected. Adsorption of immune sera with whole bacteria suggested that group 3 OMPs and 67.0K, 22.5K to 21.5K, and 19.5K to 18.0K proteins had antigenic determinants exposed on the surfaces of both B. ovis and rough B. melitensis cells but not on smooth B. melitensis cells. Antibodies to group 3 OMPs and the 67.0K protein in the sera of 93 and 87%, respectively, of B. ovis-infected rams were found by immunoblotting. Antibodies to other proteins were present in 67% of these animals. Compared with B. ovis-infected rams which had not developed lesions, rams with epididymo-orchitis had antibodies to a larger variety of proteins. Although ewes infected with B. melitensis also showed antibodies to OMPs, the immunoblot reactions were less intense.

Comparison of three serological tests for Brucella ovis infection of rams using different antigenic extracts

The sensitivity and specificity of the complement fixation, gel diffusion and ELISA tests for the diagnosis of Brucella ovis infection of rams have been compared using three different antigenic preparations. The antigens obtained by petroleum ether - chloroform - phenol, or cold saline extractions gave poorer diagnostic results than those obtained by hot saline extraction in all the tests. The best sensitivity was obtained with the ELISA (97.6 per cent) followed by the gel diffusion (96.4 per cent) and complement fixation tests (92.7 per cent). The gel diffusion test detected as positive the two rams negative in the ELISA, while the complement fixation test did not improve the sensitivity of the other tests. Under these conditions all the tests were 100 per cent specific when testing sera from rams free of B ovis.

[Paroxysmal nocturnal hemoglobinuria: physiopathology and therapeutic management]

The authors study the pathophysiology and the therapy of patients with paroxysmal nocturnal hemoglobinuria according with the literature reviewed. They also refer to have studied seven cases with HPN, two of which were women and five men, between the ages of 26 and 76 years of age, with symptomatology that varied from moderate, chronic hemolytic anemia and acholuria, to severe pancytopenia with bleeding, infections, and requiring transfusions, antibiotics, corticosteroids, androgens and other supportive measures. Most of them had enlargement of the spleen and liver, especially during hemolytic crises.

[Tobacco consumption in a group of physicians of the V Valparaiso Region (Chile)]

We surveyed 174 physicians from the Valparaiso area regarding smoking habits. 25% were smokers and 75% were not, among them 103 exsmokers (70%). A slightly higher, but not significant percentage of women smokers was observed. Compared to the general population in that area the percentage of physician smokers is significantly lower. The latter show a greater tolerance to smoking habit among their family and patients. Most doctors surveyed were not impressed by the anti-smoking campaigns of health authorities.

Isolation and characterization of a conditional replication mutant of the antibiotic resistance factor R1 affected in the gene of the replication protein repA

In vitro mutagenesis with hydroxylamine of a ParD- miniderivative of R1, pAB174, yielded mutants that were less stable in the cell than pAB174. Some of these mutants had a thermosensitive phenotype. The replication of pAB2623, one of the thermosensitive mutants, was inhibited in the cell at the restrictive temperature of 42 degrees C. The efficiency of the RepA protein of pAB2623 to promote replication of R1 in an in vitro assay was greatly reduced. Sequence analysis indicated that the repA gene of pAB2623 contains, close to its 3' end, two GC-AT transitions, separated by a single base, that change two consecutive codons of the gene. These results indicate that the phenotype of the mutant is the consequence of a mutated RepA protein and is consistent with the requirement of RepA for the in vivo replication of this plasmid.

Comparative analyses of proteins extracted by hot saline or released spontaneously into outer membrane blebs from field strains of Brucella ovis and Brucella melitensis

Sheep infected with Brucella ovis produce antibody responses to the rough lipopolysaccharide and to proteins present in hot saline (HS) extracts of B. ovis (J. I. Riezu-Boj, I. Moriyón, J. M. Blasco, C. M. Marín, and R. Díaz, J. Clin. Microbiol. 23:938-942, 1986). The distribution and antigenic relatedness of proteins in HS extracts and in outer membrane blebs were established by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blotting for 41 strains of B. ovis and 26 strains of Brucella melitensis of diverse geographic origin. Five major groups of proteins were identified in HS extracts of B. ovis that had been freed of rough lipopolysaccharide: proteins of 43 kilodaltons (kDa), group A (25.5 to 32.0 kDa), group B (21.5 to 22.5 kDa); group C (18.0 to 19.5 kDa), and group D (13.0 to 15.5 kDa). Group A, B, C, and D proteins were also present in blebs. The profiles of proteins in HS extracts or blebs from strains of both Brucella species were very similar. Cross-reactions were demonstrated among HS extracts and blebs of all strains tested in immunoblots performed with an antiserum against the HS extract of a reference strain of B. ovis. Evidence was also provided of an antigenic relationship between group 3 proteins of the outer membrane and some of the proteins in groups A, B, and C. The conservation of these antigens and their immunogenicity in infected animals provide promise that they may serve as components of an effective subcellular vaccine for ovine brucellosis.

Killing of Escherichia coli cells modulated by components of the stability system ParD of plasmid R1

The proteins P10 and P12 have been shown to be gene products of a new stability system, ParD, of plasmid R1. It is now shown that an R1 miniplasmid, pAB112, carrying a trans-complementable amber mutation in the gene of the P10 protein, is lethal for the host in the absence of suppression. This lethal effect is suppressed in a supF background and also by deletions in pAB112 that affect the gene of the P12 protein. These data indicate that the P12 protein has a lethal effect on the host and that this effect is neutralized by the P10 protein. The possibility that the stabilization conferred by the ParD system could be due to a counterselection, mediated by P12, of cells that lose the plasmid at cell division, is discussed.

Enzyme-linked immunosorbent assay with Brucella native hapten polysaccharide and smooth lipopolysaccharide

Brucella melitensis native haptens (NH) are polysaccharides identical to the O-side chain of the smooth lipopolysaccharide (S-LPS) (E. Moreno, H. Mayer, and I. Moriyón, Infect. Immun. 55:2850-2853, 1987) which precipitate with sera from infected cattle but not from strain 19-vaccinated cattle. In the present work, NH was extracted by the hot-water method (R. Díaz, J. Toyos, M.D. Salvo, and M.L. Pardo, Ann. Rech. Vet. 12:35-39, 1981) and purified free of S-LPS and protein. Purified NH lacked the ability to coat polystyrene and sheep erythrocytes. In contrast, NH acylated with stearoyl chloride bound to both polystyrene and erythrocytes. By hemagglutination and enzyme-linked immunosorbent assay (ELISA), S-LPS and acylated NH gave similar results with blood sera from brucellosis-free, strain 19-vaccinated, and infected cattle. Moreover, a significant correlation between the results of NH ELISA and S-LPS ELISA was demonstrated with milk sera. However, in a competitive ELISA with milk sera, S-LPS in the liquid phase abrogated the binding of antibodies to acylated NH adsorbed to polystyrene, while NH in the liquid phase did not influence the binding of antibodies to polystyrene-adsorbed S-LPS. It is hypothesized that the different precipitations of NH and S-LPS with sera from infected or strain 19-vaccinated cattle are due to differences in the affinity of the antibodies produced upon vaccination or infection and in the physical state of aggregation of NH and S-LPS in aqueous solutions.

Serological response to the outer membrane lipoprotein in animal brucellosis

The presence of antibodies to Brucella outer membrane lipoprotein was investigated in cattle and rams. Low but significant amounts of antibody were detected in sera from B. abortus-infected cattle and from B. ovis-infected rams which had developed epididymitis. Strain-19-vaccinated cattle also showed a weak albeit transient antibody response.

Identification of components of a new stability system of plasmid R1, ParD, that is close to the origin of replication of this plasmid

We provide evidence that a mutation which derepresses an autoregulated system that is located in the vicinity of the basic replicon of R1, stabilizes the ParA- and ParB- miniplasmid of R1 pKN1562, without increasing its copy number. The system, which we have called ParD, maps inside the 1.45-kb PstI-EcoRI fragment that is adjacent to the origin of replication of the plasmid. Two proteins whose expression is coordinated are components of the system. The sequence of the PstI-EcoRI fragment was obtained. The wild-type ParD system determines in cis a basal but detectable stability.

Immunization with Brucella melitensis Rev 1 against Brucella ovis infection of rams

The efficacy of Brucella Melitensis Rev 1 vaccine (Rev 1) for the prophylaxis of Brucella ovis ram epididymitis was evaluated. Twenty-nine 3-month-old rams were vaccinated with 2 X 10(9) Rev 1 and 14 were revaccinated with 5 X 10(8) at 14 months of age. Six rams remained unvaccinated as a control group. All rams were challenged with 5 X 10(8) B. ovis at 21 months of age. Before being slaughtered 8 weeks later, only one vaccinated ram developed epididymitis while four of the six control rams developed testicular alterations. Genital and selected extragenital organs and lymph nodes were removed at slaughter and inoculated on selective media. B. ovis was isolated from 26.6% of the vaccinated rams, 21.4% of the revaccinated rams and 100% of control rams. Portions of epididymis, testes and vesicular glands were also used for pathological studies. More severe lesions were observed in control rams than in vaccinated ones. In conclusion, these results show that vaccination of young lambs, followed or not by revaccination, is a suitable method for the prophylaxis of B. ovis infection of rams.

Influence of mouse genotype on passive systemic anaphylaxis by immune complexes

The influence of mouse genotype on passive systemic anaphylaxis (PSA) by immune complexes was studied. PSA was induced by using Brucella abortus endotoxin as the antigen and rabbit anti-Brucella endotoxin antisera. Experiments using syngeneic mice as well as mice congenic for H-2 showed that the H-2 haplotype influenced the sensitivity of mice to PSA. Among the H-2 haplotypes studied, H-2b was the most sensitive, followed by H-2k and H-2d. Experiments using passive transfer of serum as well as the complement inhibitors suramin and flufenamic acid indicated that variations in complement levels under control of H-2 may be responsible for the effects described. Cyproheptadine, a blocker of serotonin and histamine receptors, and imidazol-alpha-ketoglutarate, an inhibitor of thromboxane synthesis, inhibited PSA, indicating that platelet aggregation, possibly mediated by activated components of the complement cascade, is an important feature in the development of PSA reactions in this system. Differences between strains for protection by cyproheptadine and for the effect of complement inhibitors indicated a role of early components of the classical pathway in this model.

Analysis by coagglutination of the distribution of a 24,000-dalton surface protein in Yersinia isolates

The presence of a 24,000-dalton surface protein in 215 isolates of Yersinia enterocolitica and related species was examined. By coagglutination with the specific antiserum, a 100% correlation with the pathogenic biogroups was found. Thus, this method is useful for the rapid screening of potential pathogenic Y. enterocolitica isolates.

Characterization of a Yersinia enterocolitica antigen common to enterocolitis-associated serotypes

Yersinia enterocolitica synthesized an exocellular antigen common to the serotypes associated with enterocolitis but absent from other serotypes or from other Yersinia species. Both virulent Ca2+-dependent and avirulent Ca2+-independent isogenic pairs derived from the enterocolitis-associated serotypes synthesized the common antigen. Requirements for the synthesis of this common antigen were (i) the presence of metabolizable sugars and (ii) growth on a solid medium at 37 degrees C. The antigen was identified as a 24,000-dalton protein loosely associated with the cell surface but absent from either the cell envelope or the cytoplasmic fraction.

[Quantification (by nomograms) of physiopathological parameters in an experimental model of passive anaphylaxis caused by immune complexes]

Pharmacological changes in a model of passive anaphylaxis by immune complexes in mice have been studied. The results have been evaluated by nomograms to overcome the difficulties observed when using classical criteria as 50% lethal dosis or 50% infective dosis in experimental models which do not allow serial dilutions of the reagents. Mean lethal time, maximal pathogenic capacity and relative survival time can be easily determined, allowing the comparison of the immunopharmacologic protection for each administration schedule. By these criteria, we have observed a different degree of anaphylactic reaction depending on the genetic background of the hosts as well as a protection against anaphylactic shock using the antiserotoninic cyproheptadine and, to a lesser extent, by the platelet antiaggregant ticlopidine.