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Biomedical subjects

L Bevanger

Publications and source records attributed to L Bevanger.

At least 37 records · Page 2Linked to original sources
PubMed1992

Characterization of the alpha antigen of the c proteins of group B streptococci (GBS) using a murine monoclonal antibody.

A murine monoclonal antibody raised against the alpha antigen of the group B streptococcal c proteins was analysed by immunofluorescence and whole-cell ELISA against a collection of 22 c protein-producing GBS. All the strains showing fluorescence and reactivity in ELISA turned out to be alpha antigen-carrying strains as defined by polyclonal rabbit antisera, while none of the strains producing only the beta antigen was positive. Western blot analyses of the alpha antigen released into the culture medium of growing bacteria suggest that the alpha antigen is present as distinct proteins of variable molecular weights. The upper limit of the molecular weights varies considerably from one strain to another, from approximately 200 kD to 70 kD. With all strains, the bands seen by the MAb occurred at regularly spaced intervals of about 10 kD throughout the gel. Some strains gave rise to 15-16 bands, while others gave rise to only one or two bands. The present investigation suggests that alpha antigens include several, probably identical, repeating subunits of approximately 10 kD. The epitope recognized by the MAb seems to be located on a 10-kD fragment, and in addition, it appears to be surface located, making the MAb a suitable tool in serodiagnostic work.

Antibodies, Bacterial↗
PubMed1992

Binding of human IgA to HCl-extracted c protein from group B streptococci (GBS).

The c beta protein of group B streptococci obtained by HCl extraction appears as a ladder-like pattern in SDS-PAGE when detected by a rabbit anti-c beta serum, and a similar picture is seen when the crude extract is incubated with human IgA and an anti-human IgA conjugate. Affinity-purified c beta antigen and IgA receptors from GBS gave identical pictures in Western blots using rabbit anti-c beta serum. Both the c beta antigen and the IgA receptor are exposed on the surface of GBS as demonstrated by immunofluorescence.

Antigens, Bacterial↗
PubMed1991

Evaluation of monoclonal antibodies in serovar classification of group B streptococci (GBS). Brief report.

We have produced murine MAbs against the c protein from GBS and selected one anti-c alpha and one anti-c beta MAb for serovar classification of c-protein-producing strains. A total of 61 GBS isolates, classified by serotype-specific rabbit antisera, were tested in an immunofluorescent assay and whole-cell ELISA. The MAbs permitted classification of the isolates into 13 serovars. A total of 34 strains contained the c alpha antigen, seven strains the c beta antigen, and 20 strains both the c alpha and the c beta antigen. The distribution of GBS with regard to c-protein serovars was identical to that recorded when rabbit anti-c alpha and -c beta sera were used. The results show that the MAbs are directed against common epitopes on c alpha and beta, respectively. The MAbs will be useful in the serovar determination of clinical GBS isolates and in the study of the structure and immunobiology of c proteins.

Animals↗
PubMed1990

[Sore throat. Rapid detection of beta hemolytic group A streptococci by a coagglutination method].

In Norway anually half a million consultations are for acute sore throat. The clinical differentiation between streptococcal and non-streptococcal infection remains poor. A reliable diagnosis of beta-hemolytic streptococcal infections requires a screening test. In a multicenter study from general practice the rapid test Phadirect Strep A was compared with cultivation at two microbiological laboratories. 257 patients were included and the prevalence of beta-hemolytic streptococci was 41.6%. The results of valid calculations were: Sensitivity 70-77%; Specificity 86-89%; Positive predictive value 74-82%; Negative predictive value 81-88%. The results were considered in relation to body temperature and signs of local infection in the throat. There was no correlation between clinical signs and occurrence of beta-hemolytic streptococci. The Phadirect Strep A test was acceptably sensitive and specific for use in general practice. The test is easy to perform, and the results are available after five minutes. The test seems to be useful, and is an improvement in the daily management of patients with acute throat infections, especially in relation to the question of whether or not to prescribe antibiotics.

Agglutination Tests↗
PubMed1989

Competitive enzyme immunoassay for antibodies to a 43,000-molecular-weight Francisella tularensis outer membrane protein for the diagnosis of tularemia.

Antibodies against a 43,000-molecular-weight Francisella tularensis outer membrane (OM) protein (43K protein) were measured in paired serum specimens from 23 patients with tularemia and matched against antibodies in sera from 25 patients with nontularemic infectious diseases and from 25 blood donors. Antibodies were measured by a competition enzyme-linked immunosorbent assay which tested the ability of human serum to compete with rabbit anti-43K protein antibodies for its binding to the F. tularensis OM coat. The sera from nontularemic patients and from blood donors, in dilutions of 1:16 and 1:64, respectively, showed no or very low levels of antibodies. All of the tularemia patients showed positive tests with the first, the second, or both of the serum specimens examined. For instance, with serum diluted 1:64, each of the serum specimens showed a sensitivity of 95.7% and a specificity of 96%. When used for antibody competition in Western blotting (immunoblotting), the rabbit anti-43K selectivity blocked the binding of human serum antibodies to the 43,000-molecular-weight protein. This protein was immunoaccessible in Formalin-killed F. tularensis. These data indicate an important role of the 43,000-molecular-weight OM protein in the immunobiology of tularemia and emphasize its potential usefulness as an antigen in serodiagnostic tests.

Antibodies, Bacterial↗
PubMed1988

Agglutinins and antibodies to Francisella tularensis outer membrane antigens in the early diagnosis of disease during an outbreak of tularemia.

Tularemia was diagnosed in 57 patients during an outbreak in central Norway in 1984 and 1985. Clinical categories of the disease showed seasonal variations. A bacterial microagglutination test and an enzyme-linked immunosorbent assay (ELISA) with class-specific antibodies against Francisella tularensis outer membrane (OM) antigens were evaluated for the early diagnosis of tularemia. ELISA with immunoglobulin G (IgG), IgA, or IgM antibodies and the microagglutination test differed only marginally in diagnostic sensitivity. The OM preparation harbored F. tularensis agglutinogens and contained a variety of proteins, several of which functioned as immunogens in tularemia patients, as shown by Western blotting (immunoblotting). All 12 patients tested produced antibodies against a 43,000-molecular-weight OM protein. Individual variation was noted with regard to antibody response against other OM antigens. The OM is a suitable antigen preparation in ELISA for the diagnosis of tularemia and, presumably, contains antigens important in the immunobiology of tularemia.

Adolescent↗
PubMed1985

The Ibc proteins of group B streptococci: isolation of the alpha and beta antigens by immunosorbent chromatography and test for human serum antibodies against the two antigens.

The Ibc protein fraction from group B streptococci contains at least two antigens, named alpha and beta. Rabbit antisera to each of these antigens were used to prepare affinity-purified alpha and beta antigens. Analysis of the purified antigens by SDS-PAGE showed at least three weakly stained proteins in the alpha antigen - and multiple protein bands in the beta antigen preparation. Conditions for optimalization of ELISA for testing of human serum antibodies against these antigens were investigated. When tested at a dilution of 1 in 200, ELISA activity corresponding to an OD405 greater than 0.2 was shown by 11.2 per cent of 157 blood donor sera in tests with the alpha antigen, and 77.7 per cent with the beta antigen. Increasing antibody activity against the alpha antigen was shown by a patient with septicaemia caused by an alpha antigen-producing strain. The antigens were immunoblotted and tested against human and rabbit antibodies. With the alpha antigen, antibodies from both species produced a diffuse stained area, and with the beta antigen multiple stained bands, some of which were colinear with the human and rabbit antibody. Thus, antibodies to the beta antigen of group B streptococci are present in a large proportion of the healthy population. These antibodies may be important in the protection against group B streptococcal disease.

Animals↗
PubMed1985

Mouse-protective antibodies against the Ibc proteins of group B streptococci.

Antiserum to each of the alpha and beta antigens of the Ibc protein fraction of group B streptococci was raised in rabbits. A possible protective effect of the antisera in mice challenged by group B streptococci was evaluated. Antiserum against each of the antigens significantly increased the survival rates of mice challenged by bacteria which produced the corresponding antigen, but not of those challenged by bacteria which produced only the heterologous antigen. Animals challenged with a strain which produced both of the alpha and beta antigens were protected by antiserum to the beta antigen but not by antiserum to the alpha antigen. In this case the effect of the anti-alpha serum was a postponement of death of the animals. The antisera showed no protection of animals challenged by a group B streptococcal strain which did not produce any of the Ibc protein antigens.

Animals↗
PubMed1983

The Ibc proteins of group B streptococci: trypsin extracted alpha antigen and detection of the alpha and beta antigens.

In order to study the antigen composition of different group B streptococcal strains as regards the Ibc proteins alpha and beta, different methods for extraction were compared. Bacteria of the serotype Ic strains A909 and 335 were treated with HCl, urea, Triton-X-100, EDTA, or trypsin. Extraction with HCl was most efficient for the preparation of the beta antigen; trypsin extraction for the alpha antigen. The trypsin-extracted alpha A909 and alpha 335 antigens showed similar characteristics. Double-diffusion analysis showed a reaction of identity; on Sephacryl:S-200 filtration both appeared with peak activity at a Kav of 0.25 and on SDS-PAGE the purified preparations showed peak antigenic activity corresponding to 65,000 daltons. Hydrolysis of the alpha antigens with HCl induced minor changes in the SDS-PAGE patterns and reduction in antigenic activity. Both of the alpha antigens were immunogenic in rabbits. Antisera to the alpha 335 and beta A909 antigens were used to evaluate indirect FAT, CA, RIE, and CIE, in the detection of the antigens in 20 group B isolates. The results indicated that as a single test for the detection of alpha and beta antigens in group B streptococci, FAT or RIE should be preferred.

Animals↗
PubMed1983

Ibc proteins as serotype markers of group B streptococci.

A collection of 106 clinical isolates of group B streptococci were type classified by a direct fluorescent antibody test (FAT). In all, 99 of the isolates were typable and belonged to the serotypes Ia (8 strains), Ib (9 strains), Ic (30 strains), II (15 strains), or III (37 strains). The presence of Ibc proteins was demonstrated in 60 of the strains, including 6 of the non-typable isolates. Indirect FAT was performed to test whether the bacteria produced the alpha and beta antigens of the Ibc protein fraction, using specific anti-alpha and anti-beta sera. Both alpha and beta were produced by 22 strains, only alpha by 33 strains, and only beta by 5 strains. The results show that the alpha and beta antigens can be used as markers to detect serovars among group B strains which carry identical serotype-specific carbohydrate antigens, or strains listed as nontypable according to the classification currently used.

Bacterial Proteins↗
PubMed1981

The Ibc protein fraction of group B streptococci: characterization of protein antigens extracted by HCL.

The Ibc protein fraction of group B streptococci was prepared by HCL extraction of the type Ic strains A909 and 335. The fraction from strain A909 contained two protein antigens (alpha A 909 and beta A909) that could be separated by ion-exchange chromatography and isoelectric focusing. The 335 extract contained the alpha (alpha 335)-but not the beta antigen. The alpha 335 antigen was purified by similar procedures. The beta A909 antigen had a molecular weight of several hundred thousands, was immunogenic in rabbits and dissociated into several polypeptides on SDS-PAGE. Polypeptides with sub-unit molecular weights corresponding to 70,000 daltons showed antigenic activity. The alpha 335 antigen had a molecular weight of approximately 75,000 daltons as judged from gel filtration and SDS-PAGE. The antigen was immunogenic in rabbits. In contrast, the alpha A909 antigen showed neither protein lines on SDS-PAGE, nor immunogenicity in rabbits. However, the two alpha antigens showed serological crossreactivity in tests with the anti-alpha 335 serum.

Animals↗
PubMed1979

Complete and incomplete Ibc protein fraction in group B streptococci.

The Ibc protein fraction of group B streptococci was isolated from the type Ib strain H36B, the type Ic strain A909, and the type Ic strain 335, and examined against antisera by immunodiffusion and immunoelectrophoresis. The fraction from the Ib strain and one of the Ic strains (A909) contained two antigens or groups of antigens, called the alpha and beta antigens, respectively. Strain 335 produced the alpha but not the beta antigen. This was also the case with three other group B isolates previously classified as type Ic. One type II and one type III strian produced both antigens. The results suggest that group B streptococci producing the Ibc fraction can be subdivided further on the basis of the antigens that are present in that fraction.

Antigens, Bacterial↗
PubMed1979

Group L streptococci as the cause of bacteraemia and endocarditis. A case report.

A beta-haemolytic streptococcus was isolated from multiple blood cultures in a 56-year-old woman suffering from thrombophlebitis in a leg and from a 42-year-old man with endocarditis. Both strains were identified as group L streptococci by precipitation testing. Initially they were identified as group A streptococci on the basis of cultural characteristics, bacitracin sensitivity and fluorescent staining with an anti-group A conjugate. The two cases are an addition to the few existing reports on proved infection in humans by group L streptococci.

Bacteriological Techniques↗
PubMed1977

Type classification of group B streptococci by the fluorescent antibody test.

Fluorescein-isothiocyanate conjugates were prepared from rabbit anti-type Ia, Ib, II and III sera, and used to classify 90 strains of group B streptococci isolated from the genital tract of puerperal women. Of the 84 strains that were typeable, the numbers belonging to serotypes Ia, Ib, Ic, II and III, were 7, 14, 6, 37 and 20, respectively. The anti-type Ib conjugate showed cross-reactivity with 21 of the type II strains and one of the type III strains. Absorption of the anti-type Ib conjugate with bacteria of a type Ic strain and testing of enzyme-digested streptococci indicated cross-reactivity due to antibody to the Ibc protein antigen of group B streptococci. The potential usefulness of this antigen in the classification of type II and type III strains is discussed.

Animals↗
PubMed1976

Yersinia pseudotuberculosis as the cause of septicaemia in a patient with amyloidosis.

Septicaemia caused by Y. pseudotuberculosis in a female patient, aged 61, is reported. The patient suffered from amyloidosis with extensive infiltration of liver, spleen, and kidneys. While under treatment with corticosteroids and azathioprin, Y. pseudotuberculasis, serotype IA, was isolated from each of 6 blood cultures. The infection responded favourably to treatment with ampicillin. The development of Y. pseudotuberculosis septicaemia owing to impairment of the defence mechanisms by the underlying disease and the treatment given is discussed.

Ampicillin↗