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C A Genco

Publications and source records attributed to C A Genco.

49 records · Page 3Linked to original sources
PubMed1991

A novel mouse model to study the virulence of and host response to Porphyromonas (Bacteroides) gingivalis.

We describe here the development of a mouse subcutaneous chamber model that allows for the examination of host-parasite interactions as well as the determination of gross pathology with Porphyromonas (Bacteroides) gingivalis challenge. When inoculated into stainless-steel chambers implanted subcutaneously in female BALB/c mice, P. gingivalis W83, W50, and A7436 (10(8) to 10(10) CFU) caused cachexia, ruffling, general erythema and phlegmonous, ulcerated, necrotic lesions, and death. P. gingivalis W50/BEI, HG405, and 33277 (10(10) CFU) produced localized abscesses in the mouse chamber model with rejection of chambers at the injection site. Analysis of chamber fluid from 33277-, HG405-, and W50/BEI-infected mice by cytocentrifugation revealed inflammatory cell debris, polymorphonuclear leukocytes, and high numbers of dead bacteria. In contrast, fluid from A7436-, W50-, and W83-infected mice revealed infiltration predominantly of polymorphonuclear leukocytes and live bacteria. Bacteria were found primarily associated with polymorphonuclear leukocytes in the fluid from W50-, HG405-, and W83-infected mice but not from A7436-infected mice. Viable isolates were recoverable from the chamber fluid through day 3 for W50/BEI, day 5 for 33277, day 6 for HG405, day 7 for W50, day 14 for W83, and day 26 for A7436. All strains induced a systemic immunoglobulin G response in serum and chamber fluid samples. The use of this model will allow us to examine the virulence of P. gingivalis as defined by the interaction of host response to localized infection with P. gingivalis.

Animals↗
PubMed1990

Molecular cloning and characterization of the structural gene for the major iron-regulated protein expressed by Neisseria gonorrhoeae.

This report describes the cloning and sequencing of the major iron-regulated protein (termed Fbp) of Neisseria gonorrhoeae strain F62. Attempts to identify recombinants expressing the Fbp using specific antibody proved unsuccessful. Therefore, an alternative cloning strategy using oligonucleotide probes derived from NH2-terminal and tryptic fragments of this protein was used to identify short fragments of the gene. Using this methodology, the gene encoding the precursor of Fbp was cloned on three separate overlapping fragments and sequenced, and the amino acid sequence was deduced. These data were unambiguously confirmed by the known NH2-terminal amino acid sequence and were supported by the sequences from tryptic fragments that lie outside of this region. Using oligonucleotide probes, we were unable to obtain clones encoding the potential regulatory region of this protein. Therefore, the technique of inverse polymerase chain reaction was used to amplify a fragment containing an additional 200 bp. This fragment was cloned and sequenced and found to contain a consensus ribosome binding site and potential -10 and -35 sequences. Hybridization analysis of genomic DNA from gonococcal strain F62 indicated that only a single copy of the Fbp gene exists per genome. These results complement the biochemical characterization of the Fbp expressed by gonococci and further suggest that it has a role in iron-acquisition.

Amino Acid Sequence↗
PubMed1988

Transfer of a gonococcal beta-lactamase plasmid to conjugation-deficient Neisseria cinerea strains by transformation.

We have previously shown that some strains of Neisseria cinerea can serve as recipients in conjugation (Con+) with Neisseria gonorrhoeae while others cannot (Con-). To determine if a replication defect contributes to the inability of certain strains of N. cinerea to serve as recipients in conjugation, we attempted to introduce a naturally occurring gonococcal beta-lactamase plasmid into N. cinerea by transformation. Various methods were employed, and all proved unsuccessful. Since specific sequences are required for DNA uptake in transformation of N. gonorrhoeae, we constructed a number of hybrid plasmids containing N. cinerea chromosomal DNA inserted into the N. gonorrhoeae/Escherichia coli beta-lactamase shuttle vector, pLES2. When nine randomly selected plasmids with inserts were used to transform an N. cinerea strain which did not accept the gonococcal beta-lactamase plasmid by conjugation, transformants were observed with four of the hybrid plasmids. The presence of one of the hybrid plasmids, pCAG9, in transformants was confirmed by agarose gel electrophoresis, Southern hybridization, and beta-lactamase production. When an N. gonorrhoeae donor strain containing pCAG9 was used in conjugation with several N. cinerea strains, only those strains that were previously shown to act as recipients could accept and maintain pCAG9. The ability of pCAG9 and the other three hybrid plasmids to transform Con- strains demonstrates that the beta-lactamase plasmid can replicate in Con- strains, and, therefore, the Con- phenotype is due to a block in some other stage of the conjugation process.

Blotting, Southern↗
PubMed1988

Role of outer-membrane proteins and lipopolysaccharide in conjugation between Neisseria gonorrhoeae and Neisseria cinerea.

Little is known concerning the mechanism involved in cell contact between the donor and recipient during conjugation in Neisseria gonorrhoeae. The formation of stable mating pairs during conjugation in Escherichia coli appears to require a specific protein as well as LPS in the outer membrane of the recipient cell. To attempt to identify the cell surface components necessary for conjugation in the neisseriae, we began a comparison of the outer membrane of Neisseria cinerea strains that can (Con+) and cannot (Con-) serve as recipients in conjugation with N. gonorrhoeae. There were no differences in outer-membrane protein profiles on SDS-polyacrylamide gel electrophoresis between Con+ and Con- strains that could be correlated with the ability to conjugate. However, whole outer membrane isolated from Con+ strains specifically inhibited conjugation while those from Con- strains did not. Proteolytic cleavage of outer-membrane proteins by trypsin, pronase or alpha-chymotrypsin abolished the inhibitory effect of Con+ outer membranes, suggesting that these outer membranes contained a protease-sensitive protein(s) involved in conjugation. Although periodate oxidation of Con+ outer-membrane carbohydrates did not abolish the inhibitory action of these membranes, purified LPS from both Con+ and Con- strains inhibited conjugation when added at low concentrations. These results suggest that conjugation requires the presence of a specific conjugal receptor that consists of both LPS and one or more outer-membrane proteins. Both Con+ and Con- strains contain the necessary LPS, but only Con+ strains contain the required protein(s).

Bacterial Outer Membrane Proteins↗
PubMed1984

Conjugation of plasmids of Neisseria gonorrhoeae to other Neisseria species: potential reservoirs for the beta-lactamase plasmid.

The discovery that penicillinase production in Neisseria gonorrhoeae was plasmid mediated and the spread of the beta-lactamase encoding plasmids in gonococcal isolates since 1976, raise the possibility that a nonpathogenic indigenous bacterium could serve as a reservoir for these plasmids. We initiated studies to define the ability of commensal Neisseria species and Branhamella catarrhalis strains, as well as strains of the pathogen Neisseria meningitidis, to serve as recipients in conjugation with Neisseria gonorrhoeae. We found that with N. gonorrhoeae as the donor, 3 of 5 Neisseria cinerea, 2 of 5 Neisseria flava, 0 of 1 Neisseria flavescens, 1 of 3 Neisseria subflava, 0 of 6 B. catarrhalis, 0 of 7 Neisseria lactamica, 1 of 5 Neisseria mucosa, 1 of 7 Neisseria perflava/sicca, and 0 of 13 N. meningitidis strains gave detectable conjugation frequencies (greater than 10(-8). N. cinerea was the only species found to maintain the gonococcal conjugal plasmid (pLE2451). A N. cinerea transconjugant containing pLE2451 was observed to transfer both the beta-lactamase plasmid and pLE2451 to N. gonorrhoeae at high frequency.

Conjugation, Genetic↗
PubMedDate not supplied

Acquisition of beta-lactamase and TetM-containing conjugative plasmids by phenotypically different strains of Neisseria gonorrhoeae.

beta-lactamase plasmids confer high-level penicillin resistance on strains of Neisseria gonorrhoeae and may be mobilized between strains by conjugative plasmids. The authors examined 32 isolates belonging to 23 auxotype/serovar (A/S) classes to determine the frequency with which they acquired the 4.4-, 3.2-, and 3.05-megadalton (Mdal) beta-lactamase plasmids, respectively. The 3.05-Mdal beta-lactamase plasmid was not acquired by any isolate. Each of 22 isolates possessing only the 2.6-Mdal plasmid or both the 2.6- and 24.5-Mdal plasmids acquired the 4.4- and 3.2-Mdal plasmids at similar frequencies, and 12 (55%) acquired the 4.4- or 3.2-Mdal plasmids at a frequency of greater than or equal to 10(-3) per input recipient; all transconjugants acquired the 24.5-Mdal conjugative plasmid. Among ten isolates that lacked the 2.6-Mdal plasmid (plasmidless), seven isolates that included five PAU/IB-2, -16 isolates acquired neither the 4.4- nor 3.2-Mdal plasmid; three non-PAU isolates acquired both the 4.4- and 3.2-Mdal plasmids (10(-2)-10(-5) per input recipient). All plasmidless isolates acquired the 25.2-Mdal TetM containing plasmid with frequencies ranging from 10(-1) to 10(-8) per input recipient. These data suggest that gonococcal strains possessing the 2.6-Mdal plasmid readily acquire the 4.4- and 3.2-Mdal beta-lactamase plasmids in vitro, whereas acquisition of these plasmids by strains lacking the 2.6-Mdal plasmid is strain dependent.

Conjugation, Genetic↗
PubMedDate not supplied

Invasion strategies of the oral pathogen porphyromonas gingivalis: implications for cardiovascular disease.

Microorganisms have evolved a variety of mechanisms designed to evade detection and/or destruction by the host. Many pathogens evade host defenses by invading cells, thus providing the bacterium with an environment free of competing microorganisms. Adherence and invasion are active processes in which microorganisms often use host proteins and enzymes to gain entry into the cell, thus stimulating their own uptake. The investigation of invasion by the periopathogen Porphyromonas gingivalis is in its infancy in comparison with that of the enteric pathogens. However, recent studies with P. gingivalis have revealed that these organisms have developed invasion strategies and mechanisms similar to those of the enteric pathogens for both epithelial and endothelial cells. The study and elucidation of the mechanisms by which microorganisms such as P. gingivalis persist in chronic infection will provide valuable insight into the pathogenesis of P. gingivalis-mediated periodontal disease. The ability to multiply in and to activate endothelial cells may be one of the pathogenic mechanisms exerted by P. gingivalis that may explain the recently described association between this organism and cardiovascular disease.

Bacterial Adhesion↗