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R M Roop

Publications and source records attributed to R M Roop.

32 records · Page 2Linked to original sources
PubMed1994

Identification of an immunoreactive Brucella abortus HtrA stress response protein homolog.

An 11-kb fragment of Brucella abortus genomic DNA cloned into the BamHI site of pUC9 expressed a 60-kDa protein in Escherichia coli DH5-alpha. Antibodies reactive with this 60-kDa protein were detected by Western blot (immunoblot) analysis in sera from mice, cattle, and goats experimentally infected with B. abortus, in sera from mice experimentally infected with Brucella melitensis, and in serum from a dog experimentally infected with Brucella canis. Similar results were seen with sera obtained from cattle and dogs with naturally acquired brucellosis. The gene encoding the 60-kDa Brucella protein was localized to a 2-kb EcoRI fragment which was also reactive in Southern blots with genomic DNA from other strains of B. abortus as well as with genomic DNA from B. melitensis and B. canis. Nucleotide sequence analysis of the cloned EcoRI fragment revealed an open reading frame encoding a protein with a predicted molecular mass of 51,847 Da and an isoelectric point of 5.15. Comparison of the deduced amino acid sequence of the immunoreactive Brucella protein with the SWISS-PROT protein sequence data base revealed that it shares > 40% amino acid sequence identity with the E. coli and Salmonella typhimurium HtrA stress response proteins. Computer-assisted analysis of this amino acid sequence also predicted that the putative Brucella HtrA homolog contains an export signal sequence and a serine protease active site, two structural features characteristic of previously described HtrA proteins. A potential sigma E type heat shock promoter sequence was detected upstream of the cloned Brucella htrA gene, and Northern (RNA) blot analysis demonstrated that exposure of B. abortus 2308 to heat shock conditions resulted in a transient elevation of htrA transcription. These results strongly suggest that the immunoreactive 60-kDa Brucella protein is a member of the HtrA class of stress response proteins.

Amino Acid Sequence↗
PubMed1992

Molecular cloning and nucleotide sequence analysis of the gene encoding the immunoreactive Brucella abortus Hsp60 protein, BA60K.

A recombinant 60 kDa Brucella abortus protein expressed in Escherichia coli was recognized in immunoblots by sera from mice experimentally infected with B. abortus and a dog experimentally infected with B. canis. Sera from humans and dogs with naturally acquired brucellosis also recognized this protein, which was designated BA60K. The gene encoding BA60K was localized within an 18 kb B. abortus genomic fragment and its direction of transcription determined by subcloning and maxicell analysis of selected restriction fragments. The nucleotide sequence of 1800 bases encompassing the predicted gene location was determined, revealing an open reading frame encoding a protein of 546 amino acids (predicted relative molecular mass of 57515). Solid phase micro-sequencing of BA60K eluted from two-dimensional polyacrylamide gels confirmed the predicted amino acid sequence. Comparison of the predicted amino acid sequence of BA60K with a protein sequence database revealed that BA60K shares 67.9% identity with the GroEL protein of E. coli, a member of the Hsp60 family of chaperonins. The immunodominant Hsp60 homologs from Legionella pneumophila, Chlamydia trachomatis and Mycobacterium tuberculosis were also found to share greater than 59% amino acid sequence identity with the BA60K protein. The identification of BA60K as a member of the Hsp60 family of chaperonins supports its role in stimulating a prominent host immune response during the course of Brucella infections. It also indicates that BA60K is an important candidate for studies aimed at identifying the antigens responsible for eliciting the protective immune response to brucellosis.

Amino Acid Sequence↗
PubMed1992

Brucella abortus deficient in copper/zinc superoxide dismutase is virulent in BALB/c mice.

The gene encoding the Cu/Zn superoxide dismutase (SOD) of Brucella abortus strain 2308 was identified in a Brucella genomic library utilizing a combination of Western blotting and native gel electrophoresis. The Cu/Zn SOD gene was inactivated in vitro by ligation of a kanamycin resistance gene into the open reading frame encoding SOD. The plasmid born construct was introduced back into B. abortus by electroporation. Replacement of the wild-type Cu/Zn SOD by recombination was demonstrated by showing that both the KnR gene and the Cu/Zn SOD gene hybridized to the same band in a Southern analysis of genomic DNA. In addition, KnR strains were deficient in Cu/Zn SOD activity as assessed by lack of Cu/Zn SOD activity on a native gel and by lack of reactivity with specific serum in a Western analysis. Either strain 2308 or the Cu/Zn SOD deficient mutant injected intraperitoneally into BALB/c mice, exhibited no differences in their ability to colonize the spleen at 7 and 28 days post-inoculation. Thus, the inability to produce Cu/Zn SOD by B. abortus does not significantly impair its virulence in mice.

Animals↗
PubMed1992

Identification and purification of a cpn60 heat shock protein homolog from Helicobacter pylori.

Helicobacter pylori is associated with gastritis and peptic ulcer disease in humans. We have identified a homolog of the chaperonin cpn60 family of heat shock proteins in H. pylori, referred to as Hp54K. Hp54K, purified from water-extractable H. pylori proteins, migrated as a single band at 54 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Its native molecular mass was 740 kDa; thus, Hp54K apparently comprises a 14-mer. The N-terminal 33 residues of Hp54K exhibited 60.6, 57.6, 54.5, 54.5, 51.5, and 51.5% identity with corresponding sequences in the following cpn60 homologs: HtpB (Legionella pneumophila), P1 (human mitochondria), GroEL (Escherichia coli), BA60K (Brucella abortus), HypB (Chlamydia trachomatis), and the 65-kDa immunodominant protein of Mycobacterium bovis BCG, respectively. Hp54K was the only protein recognized in whole-cell preparations of H. pylori by immunoblotting using monospecific antisera against cpn60 homologs from L. pneumophila, E. coli, C. trachomatis, and M. bovis BCG. Antiserum against Hp54K recognized proteins with molecular masses of 50 to 60 kDa in a large number of gram-negative bacteria, consistent with the known highly conserved nature of cpn60 proteins. Hp54K is a major protein and is immunogenic in humans infected with H. pylori. Thus, Hp54K shares many similarities with known cpn60 homologs. On the basis of the proposed role of other cpn60 proteins in induction of chronic inflammation, immune cross-reactivity between Hp54K and gastric tissue may provide an important link between H. pylori infection and gastritis.

Amino Acid Sequence↗
PubMed1991

Experimental infection of goat fetuses in utero with a stable, rough mutant of Brucella abortus.

Fetuses of goats in their last trimester of pregnancy were experimentally infected with Brucella abortus strain RB51, a stable rough mutant deficient in the perosamine O-chain content of its lipopolysaccharide. RB51 maintained its rough phenotype in vivo and did not induce abortion. Infection with RB51 resulted in the production of significant levels of IgG type antibodies specific for B abortus cellular antigens distinct from the perosamine O-chain. These findings suggest that strain RB51 will be useful in the pregnant goat for studying the role of brucella antigens other than the lipopolysaccharide O-chain in the immune response to brucellosis.

Animals↗
PubMed1991

Biological properties of RB51; a stable rough strain of Brucella abortus.

A rifampin-resistant mutant of Brucella abortus, designated RB51, was derived by repeated passage of strain 2308 on Trypticase soy supplemented with 1.5% agar and varying concentrations rifampin or penicillin. The RB51 colonies absorbed crystal violet and RB51 cell suspensions autoagglutinated, indicating a rough type colonial morphology for this strain. No O-chain component was detected in lipopolysaccharide (LPS) extracted from RB51 on SDS-PAGE gels stained with silver. Western blot analysis with the monoclonal antibody BRU 38, which is specific for the perosamine homopolymer O-chain of smooth Brucella LPS, indicated that the LPS of RB51 is highly deficient in O-chain when compared with the parenteral smooth strain 2308 or rough strain 45/20. Biochemically, RB51 resembles parental strain 2308 in its ability to utilize erythritol. Intraperitoneal inoculation of RB51 into mice results in a splenic colonization which is cleared within four weeks post infection. RB51 does not revert to smooth colony morphology upon passage in vivo (mice) or in vitro. Mice infected with RB51 produce antibodies against B. abortus antigens including class 2 and 3 outer membrane proteins but not against the O-chain. Furthermore, rabbits, goats and cattle hyperimmunized with sonicates of RB51 develop antibodies to B. abortus cellular antigens but do not develop antibodies specific for the O-chain. Immunization of mice with 1 x 10(8) viable RB51 organisms confers significant protection against challenge with virulent B. abortus strain 2308.

Animals↗
PubMed1991

Serum sensitivity and lipopolysaccharide characteristics in Bordetella bronchiseptica, B. pertussis and B. parapertussis.

The viability of four strains of Bordetella bronchiseptica, two strains of B. pertussis and one strain of B. parapertussis exposed to hyperimmune and pre-colostrum porcine serum was examined. Viable cell numbers (cfu/ml) of the B. pertussis strains and a rough strain of B. bronchiseptica (CSU-P-1) decreased by 99% and 99.99%, respectively, after exposure for 1 h to porcine hyperimmune serum. In contrast, smooth B. bronchiseptica strains and the B. parapertussis strain showed no significant decrease in viable cell numbers after the same treatment. B. bronchiseptica strain CSU-P-1 also showed a 99% decrease in viable cell numbers after exposure to pre-colostrum porcine serum for 1 h whereas the other strains tested showed no decrease in viable numbers under the same conditions. Heating the hyperimmune and pre-colostrum serum at 56 degrees C for 30 min resulted in the loss of bactericidal activity suggesting the involvement of complement in both systems. Analysis of silver-stained SDS-PAGE profiles of lipopolysaccharide (LPS) extracted from the bacterial cells indicated that the smooth strains of B. bronchiseptica and the B. parapertussis strain possessed high mol. wt O-side chain-like material, whereas the B. pertussis strains and B. bronchiseptica strain CSU-P-1 did not. Gel filtration of acid-hydrolysed LPS samples indicated two distinct carbohydrate peaks for the strains with high mol. wt O-side chain-like material, whereas the other strains each yielded one distinct peak. Western-blot analysis indicated a positive reaction for anti-B. bronchiseptica antibodies to the high mol. wt O-side chain-like material of all serum-resistant strains used in this study.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Virulence factors of Bordetella bronchiseptica associated with the production of infectious atrophic rhinitis and pneumonia in experimentally infected neonatal swine.

Four strains of Bordetella bronchiseptica (CSU-P-1, 64-C-0406, 1120-A-83-013, and B205BT) with defined virulence for neonatal swine were examined, and an attempt was made to correlate the presence of certain in vitro phenotypic characteristics with the ability of a particular B. bronchiseptica strain to produce turbinate and lung lesions in piglets. All of the strains except CSU-P-1 colonized the nasal passages of the pigs heavily, and strains 1120-A-83-013 and B205BT produced moderate to severe nasal and lung lesions in experimentally infected piglets. All of the strains attached equally well to porcine tracheal ring explant cultures, and all of the strains except CSU-P-1 produced smooth, hemolytic colonies on Bordet-Gengou medium, agglutinated porcine erythrocytes, and possessed adenylate cyclase activity. Strains 1120-A-83-013 and B205BT produced considerably higher levels of dermonecrotic toxin activity than did strains CSU-P-1 and 64-C-0406. These results indicate that production of nasal and lung lesions in neonatal piglets by the B. bronchiseptica strains tested can be directly correlated with their level of dermonecrotic toxin production.

Adenylyl Cyclases↗
PubMed1987

Rapid identification of smooth Brucella species with a monoclonal antibody.

A colony blot enzyme-linked immunosorbent assay was developed for the rapid identification of smooth Brucella species, i.e., Brucella abortus, B. melitensis, and B. suis. Bacterial colonies from plates were blotted onto nitrocellulose disks, lysed by immersion in chloroform, and reacted with BRU 38, a rat monoclonal antibody with specificity for the O side chain of B. abortus. Reaction with anti-rat immunoglobulin G conjugated to horseradish peroxidase and development in 4-chloro-1-naphthol resulted in colonies of naturally occurring smooth Brucella species staining purple. Results could be obtained within 4 h after colonies were visible on plates and individual colonies could be detected. Yersinia enterocolitica serovar O:9 strains were the only other organisms tested which showed cross-reaction by using this procedure. Because of its speed, sensitivity, and specificity, this technique should be very useful for identifying smooth Brucella strains in diagnostic laboratories.

Animals↗
PubMed1985

DNA homology studies of the catalase-negative campylobacters and "Campylobacter fecalis," an emended description of Campylobacter sputorum, and proposal of the neotype strain of Campylobacter sputorum.

Twenty-three strains of catalase-negative campylobacters and five strains of "Campylobacter fecalis," which is catalase-positive, were examined by DNA hybridization experiments. These organisms formed four distinct DNA homology groups corresponding to Campylobacter sputorum, Campylobacter mucosalis, Campylobacter concisus, and a currently unnamed group referred to as the "catalase-negative or weak" (CNW) strains. The strains were further characterized to determine which phenotypic characteristics provide the most reliable identification at the species level. Campylobacter sputorum ssp. sputorum, C. sputorum ssp. bubulus, and "C. fecalis" could not be distinguished by DNA homology; consequently, it is proposed that these three taxa be considered as biovars of C. sputorum. The description of C. sputorum is emended accordingly. ATCC strain 35980 is proposed as the neotype strain of C. sputorum.

Campylobacter↗
PubMed1984

Improved biotyping schemes for Campylobacter jejuni and Campylobacter coli.

Campylobacter jejuni (20 strains) and Campylobacter coli (12 strains) were assigned to four biovars for each species based on phenotypic tests that were easy to perform and interpret. The resulting biotyping schemes offer a greater degree of distinction among C. jejuni and C. coli strains than any of the other biotyping schemes previously described for these organisms.

Alkaline Phosphatase↗
PubMed1984

Differential characteristics of catalase-positive campylobacters correlated with DNA homology groups.

Eighty-four strains of catalase-positive campylobacters could be placed into seven distinct DNA homology groups (species), corresponding to Campylobacter fetus, "C. hyointestinalis," C. jejuni, C. coli, "C. laridis," "C. fecalis," and aerotolerant campylobacters. The biochemical and physiological characteristics of the strains were examined for their correlation with the homology groups. The characterization tests that provided the most reliable differentiation at the species and subspecies level were growth at 25 and 42 degrees C, sensitivity to cephalothin and nalidixic acid, growth in semisolid media containing 1% glycine and 3.5% NaCl, growth on plates containing 1.5% NaCl, growth in a semisolid minimal medium, anaerobic growth in the presence of 0.1% trimethylamine-N-oxide, hydrogen sulfide production in SIM medium and triple-sugar iron agar, hippurate hydrolysis, nitrite reduction, and growth on plates under an air atmosphere.

Aerobiosis↗
PubMedDate not supplied

A Brucella melitensis high-temperature-requirement A (htrA) deletion mutant is attenuated in goats and protects against abortion.

It has been previously demonstrated that a Brucella melitensis high-temperature-requirement A (htrA) deletion mutant is more susceptible to oxidative killing in vitro than the parental strain and is attenuated in mice. To evaluate the contribution of the B melitensis HtrA protease to virulence in ruminants, the capacity of the B melitensis htrA mutant RWP5 to produce abortion in goats was compared to that of the virulent parental strain 16M. Experimental infection with strain 16M caused abortion in eight of 12 pregnant nannies, while none of the 12 nannies inoculated with RWP5 aborted. Furthermore, intramuscular injection of fetuses in utero with RWP5 led to colonisation of the fetus with subsequent colonisation of the nanny, but no abortion was observed. Nannies vaccinated with RWP5 showed complete protection against abortion when challenged with 16M during the third trimester of pregnancy. However, these animals were not protected from colonisation by 16M. The results presented here clearly indicate that the B melitensis htrA gene product contributes to pathogenesis in goats, but the utility of B melitensis htrA mutants as vaccines in this host appears to be limited.

Abortion, Veterinary↗