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N A Vedros

Publications and source records attributed to N A Vedros.

At least 19 recordsLinked to original sources
PubMed1992

Immunochemical analysis and possible biological role of an Aeromonas hydrophila surface array protein in septicaemia.

The biochemical, immunological, and biological properties of an S layer purified from an Aeromonas hydrophila strain (AH-342) involved in a case of bacteraemia were investigated. The S layer selectively removed from the cell surface was composed of a single acidic (pI 4.56) protein subunit (surface array protein, SAP) with a molecular mass of approximately 52 kDa. Amino acid analysis of this 52 kDa protein indicated a molecule composed of 498 amino acids with 46% hydrophobic residues. No cysteine residues were detected. The first 35 residues of the N-terminus were sequenced by Edman degradation; only 4-24% homology was noted between this sequence and those previously published for SAPs of Aeromonas salmonicida (A450) and a strain of A. hydrophila (TF7) originally isolated from a moribund fish. Polyclonal antibodies raised against AH-342 SAP were genospecific, reacting only against S layers produced by A. hydrophila strains and not those from Aeromonas veronii. Acute serum from the bacteraemic patient from whom AH-342 was isolated reacted strongly with the SAP of AH-342 in immunoblot studies. Purified SAP, when intraperitoneally co-inoculated with SAP- strains of A. hydrophila into Swiss-Webster mice, could reduce the 50% lethal dose by approximately 30-70 fold. The results suggest that the SAP of A. hydrophila strains may play an important role in systemic dissemination after invasion through the gastrointestinal mucosa.

Aeromonas hydrophila↗
PubMed1991

Characterization of classic and atypical serogroup O:11 Aeromonas: evidence that the surface array protein is not directly involved in mouse pathogenicity.

A number of different techniques were used to analyse classic and atypical serogroup O:11 Aeromonas isolates. Five of seven atypical O:11, S layer-negative strains lacking a homogeneous LPS side-chain pattern exhibited varying degrees of mouse pathogenecity. One virulent atypical strain (AH-77) synthesized a surface array protein (SAP) but was unable to anchor it to the cell surface in an intact form, presumably due to a defect in its LPS architecture. Proteinase K digestion to remove the SAP, or growth at elevated temperatures (42 degrees C) to reduce the proportion of SAP synthesized from classic O:11 S layer-positive strains, did not alter their LD50 values in outbred mice. In addition, a spontaneous mutant, AS-180-1, that was S layer-negative was as virulent as the parental S layer-positive strain in the mouse model. These results suggest neither the SAP nor the characteristic serogroup O:11 homogeneous LPS side-chain pattern are directly involved in mouse pathogenicity.

Aeromonas↗
PubMed1990

Electrophoretic analysis of the surface components of autoagglutinating surface array protein-positive and surface array protein-negative Aeromonas hydrophila and Aeromonas sobria.

The protein and lipopolysaccharide (LPS) compositions of 10 autoagglutinating Aeromonas hydrophila and Aeromonas sobria strains were studied; one group consisted of five serogroup O:11 strains that contained an S layer, while a second group was composed of diverse serogroups that were S layer negative by transmission electron microscopy. All serogroup O:11 strains were found to contain a predominant 52,000- to 54,000-molecular-weight protein that was present on both whole-cell and outer membrane protein profiles; this protein was found to be glycine extractable under low-pH (pH 4) conditions and was identified as the surface array protein. LPS analysis revealed that all O:11 strains exhibited homogeneous-length O-polysaccharide side chains characterized primarily by two or three major bands. In contrast, S-layer-negative autoagglutinating strains of other serogroups lacked this predominant surface array protein, and silver stain analysis of LPS indicated that such profiles mainly consisted of core antigens and were deficient in or devoid of O-polysaccharide side chains. These collective results offer potential explanations for observed differences between these two groups in virulence, disease spectrum, and pathogenic properties.

Aeromonas↗
PubMed1990

New marine calicivirus serotype infective for swine.

A new serotype of calicivirus was isolated from California sea lions (Zalophus californianus) with severe vesicular disease. Neutralizing antibodies were found in 27 of 82 (32.9%) serum samples from California sea lions and in 15 of 146 (10.3%) serum samples from Steller sea lions (Eumetopias jubatus) tested. The seropositive animals were widely dispersed along the margins of the eastern Pacific basin, from the Bering Sea to the Santa Barbara Channel. Seropositive samples were found from as early as 1976 through the present time. This new calicivirus serotype, San Miguel sea lion virus type 13, was inoculated into weaned pigs, resulting in induction of severe vesicular disease, which spread to all pigs, including uninoculated pen contacts. Virus was continually shed by most of the pigs throughout the 2-week duration of the experiment.

Animals↗
PubMed1987

Sialic acid of group B Neisseria meningitidis regulates alternative complement pathway activation.

The effect of meningococcal cell-associated sialic acid on activation of the human alternative complement pathway was examined by using a quantitative fluorescence immunoassay to assess alternative pathway-mediated C3 binding to a group B strain of Neisseria meningitidis from which graded amounts of sialic acid had been removed with neuraminidase. Using human serum absorbed with strain B16B6 (B:2a:L2,3) and chelated with 10 mM MgCl2 and 10 mM ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid, we found an increase in the amount of C3 bound by enzymatically desialylated B16B6 organisms over the amount bound by fully sialylated organisms. This increase was proportional to the amount of sialic acid cleaved from the bacteria. Enhanced C3 binding was accompanied by an increase in factor B deposition. A sialic acid-deficient mutant of strain B16B6, designated 2T4-1, bound C3 via the alternative pathway at a level equivalent to that bound by wild-type meningococci from which 88% of the sialic acid had been removed. Strain B16B6 was resistant to the alternative pathway-mediated bactericidal activity of both absorbed and hypogammaglobulinemic human sera, whereas noncapsular variant 2T4-1 was sensitive to these sera. The addition of purified immune immunoglobulin M (IgM) and IgG significantly increased the alternative pathway-mediated killing of strain B16B6 organisms. IgM mediated increased bactericidal activity without an increase in C3 or factor B deposition. In contrast, the IgG-mediated killing was associated with increased binding of C3 and factor B to the organisms. Absorption studies showed that the IgM bound to the sialic acid capsule, whereas the IgG bound to noncapsular surface antigens. We conclude from these results that the group B meningococcal sialic acid capsule inhibits activation of the alternative pathway in the nonimmune host and that both IgM and IgG, although specific for different surface antigens, are capable of augmenting the alternative pathway-mediated killing of group B meningococci.

Antibodies, Bacterial↗
PubMed1985

Genetic relationships among Neisseria species assessed by comparative enzyme electrophoresis.

The electrophoretic mobilities of 12 enzymes from 19 Neisseria species (including 6 strains of N. perflava), Gemella haemolysans, Escherichia coli and Branhamella catarrhalis were characterized by polyacrylamide slab gel electrophoresis. All strains and species tested exhibited qualitatively different zymogram patterns. Species and strain relationships were quantified by pairwise comparisons of all 12 enzyme systems to obtain similarity indices; these data were subjected to numerical clustering methods to obtain groups and a phenogram. The electrophoretic classification compared favourably with those obtained by other criteria. In addition, the quantitative clustering data indicated that N. ovis and N. caviae are sufficiently different from the other Neisseria species to warrant their separation into a distinct group. These two species also lacked the characteristic NADPH-diaphorase zymogram pattern found in all the other Neisseria species. Intra-species similarity indices were generally greater than the inter-species index values. However, certain species such as N. meningitidis and N. gonorrhoeae had similarity index values in the range of inter-strain index values.

Dihydrolipoamide Dehydrogenase↗
PubMed1983

Passive immunization in murine mucormycosis.

Antibody raised in mice against mycelial homogenates of Rhizomucor pusillus was effective in passive immunization against pulmonary and disseminated mucormycosis (phycomycosis) in immunocompromised mice. Mice intranasally inoculated and infected with Rh. pusillus and treated with antisera had a statistically significant increased resistance to infection and a diminished secondary dissemination of viable fungal fragments. Histological examination of infected lung tissues showed that antibody treated animals were apparently able to degrade hyphal fragments.

Animals↗
PubMed1983

Immunodiffusion and complement fixation assays with sera from mucormycotic-infected mice.

Results using homogenate antigens of Rhizomucor pusillus against immunized rabbit sera, mouse ascites fluid and sera from mucormycotic-infected mice, detected by immunodiffusion and complement fixation assays are presented. Using immunodiffusion techniques, common antigens and unique antigens from Rh. pusillus, Rhizopus oryzae and Absidia corymbifera were observed. Complement fixation titers of greater than 256 and 128 were obtained in immunized rabbit sera and mouse ascites fluid, respectively. However, no appreciable titers of antibody were measured from mucormycotic-infected animals by either immunodiffusion or complement fixation.

Animals↗
PubMed1982

Murine model of pulmonary mucormycosis in cortisone-treated mice.

Intranasal inoculation of Rhizomucor pusillus sporangiospores into cortisone-treated mice produced pulmonary and disseminated mucormycosis (phycomycosis). Evidence for infection in cortisone treated mice was obtained by recovery of Rh. pusillus from homogenates of tissue. Confirmation of infection was shown histologically. The 50% infectious dose was 2.4 x 10(2) colony forming units for lung infections and 2.7 x 10(5) colony forming units for brain infections. No evidence of sporangiospore germination was found in tissues of non-cortisone-treated mice although sporangiospores were found throughout pulmonary tissues. In infected tissues of cortisone-treated mice, hyphae were covered with leukocytes and tissue necrosis was extensive.

Animals↗
PubMed1982

Characterization of atypical aerobic gram-negative cocci isolated from humans.

Six atypical aerobic gram-negative cocci, isolated from humans, were classified taxonomically by genetic relatedness (DNA base pairs and DNA homology), fatty acid content, pigment absorption profile, and other physiological and biochemical characteristics. One strain (M448), which produced acid only from glucose, was identified as Neisseria meningitidis; one strain (CH), which produced acid from glucose, maltose, and sucrose, was identified as N. gonorrhoea; Branhamella catarrhalis was confirmed in a case of acute meningitis; N. canis was identified in a cat bite wound; and representative isolates of a proposed new pigmented species were found to have genetic affinities with N. meningitidis and N. perflava.

Base Sequence↗
PubMed1982

Bacterial and fungal flora of wild northern fur seals (Callorhinus ursinus).

Tissues from healthy subadult and moribund newborn northern fur seals (Callorhinus ursinus) on St. Paul Island, Pribilof Islands, Alaska, and from healthy pups and yearlings on San Miguel Island, California, were sampled for bacteria and fungi. Corynebacterium spp. and Staphylococcus spp. were more frequently present in tissues from animals on St. Paul Island whereas Pseudomonas spp. were frequently isolated on San Miguel Island. Approximately half of the blood samples were positive for bacteria. Salmonella spp. were isolated from rectal swabs of animals only on San Miguel Island. Fungi were isolated from the hair and skin of subadult males.

Age Factors↗
PubMed1981

Biphasic resin system for growing concentrated cultures of microorganisms and its application to the cultivation of Neisseria gonorrhoeae.

A technique is described in which a polyester casting resin is used instead of agar for the growth of Neisseria gonorrhoeae in a biphasic system. In complex medium, higher concentrations and stability of T1 colony type were obtained with resin than with either agar or broth alone after 24 h of incubation. In defined medium, the growth of gonococci and colony type stability were similar in single-phase and resin systems and superior to the growth and stability occurring in the biphasic agar system.

Bacteriological Techniques↗
PubMed1979

Fatty acid content of depot fat in the northern fur seal (Callorhinus ursinus).

The fatty acid content of depot fat samples from 15 northern fur seals (Callorhinus ursinus) were determined by gas-liquid chromatography. Callorhinus ursinus has a high proportion of short chain saturated acids: C10, C11, C12, C13, C15. Unsaturated longer chain acids C16:1, and C16:2, and C18:1 also were found. Results obtained are compared to a previously reported milk lipid analysis of the northern fur seal.

Adipose Tissue↗
PubMed1978

Hazards of disease transfer from marine mammals to land mammals: review and recent findings.

In a 5-year study (1972-1977) of microbial agents isolated from both clinically normal and diseased marine mammals, it was shown that certain disease agents are widespread in a diversity of ocean populations and that some are also transmissible to a number of terrestrial mammal species. Leptospira interrogans serovar pomona has been isolated repeatedly from 2 species of pinnipeds (Zalophus californianus califonianus and Callorhinus ursinus). Some of the more important bacterial pathogens for land mammals that were isolated from wild marine mammals are Pseudomonas mallei, Clostridium chauvoei, C novyi, Neisseria mucosa var heidelbergensis, Klebsiella pneumoniae, Salmonella spp, and Pasteurella multocida. Numerous serotypes of viruses classified as caliciviruses were isolated from a variety of marine mammals. Some of these are known to infect several land mammal species including swine horses, and primates. For this reason., precautions should be taken to ensure that disease agents shed by captive marine mammals are not transmitted to susceptible terrestrial mammals, including animal handlers and other human beings.

Animals↗
PubMed1977

Host range comparisons of five serotypes of caliciviruses.

Two new serotypes of San Miguel sea lion virus (SMSV), designated SMSV-4 and SMSV-5, were studied in vivo and in vitro. The host cell spectrums were compared with SMSV-1, SMSV-2, and vesicular exanthema of swine virus type A-48. Based on the result of these broad host spectrums, a numerical scoring system was devised for ranking each virus on the basis of its potential for infecting terrestrial mammals, including the important domestic species.

Animals↗
PubMed1975

Method for detecting antibody formation to Neisseria gonorrhoeae.

The use of Concanavalin A as a coupling agent for sensitization of sheep erythrocytes with an alkaline extract of Neisseria gonorrhoeae organisms is described in this paper. The sensitized erythrocytes were used in a plaque assay for enumeration of antibody-producing cells and in hemagglutination and hemolysin tests for determination of serum antibody. Rabbits were immunized intraperitoneally, intravenously, or via the footpad with viable N. gonorrhoeae organisms. Plaque-forming cells were found in draining lymph nodes and in the spleens of these rabbits. The cells from some rabbits also lysed sheep erythrocytes coated with an alkaline extract prepared from Neisseria meningitidis organisms. No antibody-producing cells were found in the lymphoid tissues of normal rabbits. Rabbits immunized by all three routes developed high hemagglutination and hemolysin titers. Hemolysin titers were significantly higher than hemagglutination titers when both tests were performed on the same serum samples. Pooled antiserum from these rabbits also lysed erythrocytes coated with a meningococcal antigen, but titers for the specific immunizing species were higher.

Animals↗