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B Niklasson

Publications and source records attributed to B Niklasson.

At least 37 records · Page 2Linked to original sources
PubMed1996

Ockelbo virus (Togaviridae: Alphavirus) neutralizing antibodies in experimentally infected Swedish birds.

The ability of native Swedish birds to produce and maintain production of Ockelbo virus neutralizing (Nt) antibodies were evaluated experimentally between 6 June 1990 and 27 July 1991. After experimental infection of 57 birds of the orders Anseriformes and Passeriformes with Ockelbo virus, these birds were examined for Ockelbo virus Nt antibodies at 5 days, and at 1, 3, 6, 9, and 12 mo after inoculation. One month after inoculation, Nt antibodies were more prevalent in birds with a detectable viremia (100%, n = 22) than in non-viremic birds (65%, n = 26). The Nt antibody prevalence varied over time among taxa; detectable antibodies occurred earlier after inoculation and for a longer time in Anseriformes than in Passeriformes. By 5 days after inoculation, antibodies could be detected in 22 (71%) of 31 Anseriformes but in none of 16 Passeriformes. However, at 1 mo the antibody prevalences at 1 mo were similar: 84% among the Anseriformes and 73% among the Passeriformes; at 3 mo the prevalences were 50% in Anseriformes and 15% in Passeriformes. Forty-two percent of the Anseriformes had detectable antibodies even 12 mo after inoculation.

Alphavirus↗
PubMed1995

Antigenic relationships of hantavirus strains analysed by monoclonal antibodies.

The antigenic relationships among 71 hantavirus strains, isolated from rodent species or humans in several geographic regions, were examined by immunofluorescence assay (IFA) using human patient sera and a panel of 22 monoclonal antibodies prepared against Hantaan, Seoul, and Puumala viruses. The study included virus strains, mainly from the former USSR, for which little or no serological data were available. Fifty-nine of the 71 isolates could be placed into five antigenic groups of hantaviruses, Hantaan (HTN), Puumala (PUU), Seoul (SEO), Prospect Hill (PH), Dobrava/Belgrade (DOB). Twelve isolates were found antigenically closely related to, but distinct from, HTN (2 strains), PUU (4 strains) and PH (6 strains), respectively. The antigenic characteristics of these 12 isolates suggested two supplementary antigenic subgroups of HTN, one of PUU, and two of PH. The two antigenic subgroups of HTN included strains isolated in the Far-East of Russia. The PUU subgroup included strains isolated in European Russia as well as strains isolated in Far-Eastern Russia. The PH group comprised two subgroups, both represented by strains isolated from M. fortis in Far-Eastern Russia. The results showed that the PUU and PH antigenic groups are more complex than previously known and that PH-like virus strains isolated in Russia are antigenically more closely related to PUU virus when compared to prototype PH virus isolated in the USA.

Antibodies, Monoclonal↗
PubMed1995

Sensitive detection of hantaviruses by biotin-streptavidin enhanced immunoassays based on bank vole monoclonal antibodies.

Antigen capture enzyme-linked immunosorbent assays (ELISAs) based on detection of the viral nucleocapsid protein (N) were designed for rapid diagnosis of hantavirus infections. Several combinations of bank vole (Clethrionomys glareolus) monoclonal antibodies with various N-epitope specificities were used for the development of two double-antibody sandwich forms of ELISA; PUU virus AG-ELISA for an exclusive detection of Puumala-related viruses, and Hantavirus AG-ELISA for a more extensive detection of all serotypes of hemorrhagic fever with renal syndrome (HFRS) viruses. The biotin-streptavidin system, in combination with horseradish peroxidase, rendered the assays' sensitivities similar to or even higher than immunoblotting. Calculated detection limits for the PUU virus and the Hantavirus AG-ELISAs were 405 and 50 focus forming units or 80 and 10 infected Vero E6 cells, respectively. The assays were evaluated and found to be suitable for convenient and routine detection of hantaviruses in cell cultures and in infected animal tissue.

Animals↗
PubMed1995

Nucleotide and deduced amino acid sequences of the M and S genome segments of a Swedish Puumala virus isolate.

The Swedish Puumala (PUU) virus strain Vindeln 83-L20, isolated from a bank vole trapped in 1983 near Vindeln, Västerbotten county, Sweden, was characterized by nucleotide sequence analysis. The coding region of the M segment was determined by PCR followed by direct sequencing and the entire S segment was characterized by cloning and nucleotide sequence analysis. The genomic organization was found to be very similar to that of other PUU virus strains regarding open reading frames, polypeptide sizes and potential glycosylation sites. According to phylogenetic analysis 83-L20 was found to represent a new lineage within the Puumala virus serotype in the Hantavirus genus. The M segment sequence of 83-L20 was found to be more closely related to the Finnish PUU virus strains than to strains from Central Europe or from Russia. The evolutionary origin of the S segment was not as clearly resolved since the branching points of all PUU virus strains in the phylogenetic tree were nearly the same.

Amino Acid Sequence↗
PubMed1995

Indirect immunofluorescence for serological diagnosis of dengue virus infections in Swedish patients.

BACKGROUND: An increasing number of travellers to dengue endemic areas has emphasized the need for an easy and reliable serological test for diagnosis of dengue virus infections. OBJECTIVES: Indirect immunofluorescence (IF) and hemagglutination inhibition (HI) tests were compared for serological diagnosis of dengue fever (DF). STUDY DESIGN: Sera from patients with clinical symptoms compatible with DF and a travel history comprising dengue endemic areas were included in the study. Paired serum samples from 24 patients and single convalescent sera from five patients were investigated by HI and IF. Paired sera from ten patients were investigated by plaque reduction neutralization test (PRNT) in order to confirm the HI/IF results. RESULTS: In twelve of the patients with paired sera a sero-conversion or a significant (4-fold) antibody titer rise was seen with HI as well as with IF. Four patients with stationary HI-titers had significant titer rises when investigated by IF. Stationary or declining HI- and IF-titers were found in the remaining eight patients. The five single sera were antibody-positive by both methods. Investigation by PRNT of paired sera from ten patients confirmed the IF results. A total of 298 serum samples (paired sera or early convalescent samples) were investigated for dengue antibodies by IF. A sero-conversion, significant titer-rise or an IF-titer of 320 was generally seen 7-13 days post onset of disease. During the years 1991-1993 altogether 161 cases of dengue were diagnosed by IF in Swedish patients, a majority of which had travelled to Southeast Asia. CONCLUSION: Antibody detection by indirect IF proved to be at least as reliable as HI for diagnosis of dengue infections in Swedish patients. The specificity of the IF was ensured by testing the sera of ten patients for serotype specific neutralizing dengue antibodies.

Journal Article↗
PubMed1995

Mapping of B-cell determinants in the nucleocapsid protein of Puumala virus: definition of epitopes specific for acute immunoglobulin G recognition in humans.

The complete amino acid sequence of the Puumala (PUU) virus nucleocapsid protein (N), deduced from the genome of the prototype strain Sotkamo, was synthesized as decapeptides with 5-amino-acid overlaps. By use of the PEPSCAN method, 86 peptides were examined for reactivity with sera from serologically confirmed nephropathia epidemica (NE) patients and 11 PUU virus N-specific bank vole monoclonal antibodies. The human sera showed reactivity with several different regions, while only one of the monoclonal antibodies reacted with one single peptide. Sequences were selected by this PEPSCAN analysis of human antibody reactivities, and five 15-amino-acid peptides were synthesized and evaluated as antigens by an enzyme-linked immunosorbent assay (ELISA). Peptide-reactive antibodies of the immunoglobulin M (IgM) class were measured in serum samples drawn from patients with acute NE. In comparison with the results of a mu-capture IgM ELISA using native PUU virus antigen, only a few serum samples were found positive (sensitivity, 2 to 10%). Interestingly, when antibodies of the IgG class were measured, the sensitivities of the five peptide ELISAs were found to be 79, 46, 2, 100, and 40%, respectively, as compared with the sensitivity of an IgG ELISA based on native viral antigen. The IgG reactivities of sequentially drawn sera from NE patients with the two peptides giving the highest assay sensitivities were analyzed and compared with their reactivities with native viral antigen. All patients had detectable anti-peptide IgG in the acute-phase sample, which, however, had totally declined in samples drawn after 2 years. The opposite pattern was seen with native viral antigen, in which case all patients showed the highest levels of specific IgG after 2 years. The results suggest the presence of epitopes specific for the acute IgG response.

Acute Disease↗
PubMed1995

Detection and subsequent sequencing of Puumala virus from human specimens by PCR.

A sensitive method based on PCR was developed for the detection of Puumala virus (PUU) in human samples. The assay was found to be specific for PUU-like strains and distinguished between these and hantaviruses of other serotypes. The detection limit was found to be 10(-5) focus-forming units. Clinical samples were collected from patients with nephropathia epidemica in Sweden and western Russia. Five whole blood samples collected from patients in Russia with the acute phase of disease were found to be positive by the PCR. All samples were negative for PUU antigen when examined by enzyme-linked immunosorbent assay. Virus isolation on Vero E6 cells from several of the acute-phase samples, including the 5 PCR-positive samples, was not successful. The amplified samples were subjected to direct nucleic acid sequencing for confirmation of identity. The sequences differed from each other and were closely related to the Russian bank vole isolate CG-1820, thereby indicating the origin of nephropathia epidemica. The PCR was used for amplification and subsequent nucleotide sequencing of eight PUU-like isolates with different geographic origins. The Swedish strains were more closely related to the Finnish PUU prototype strain, Sotkamo, than to the Russian isolates. Interestingly, a Belgian isolate, CG-13891, differed markedly from all other PUU strains.

Animals↗
PubMed1995

Temporal dynamics of Puumala virus antibody prevalence in voles and of nephropathia epidemica incidence in humans.

Puumala (PUU) virus is the etiologic agent of nephropathia epidemica (NE) in humans. This disease is highly endemic in Vasterbotten county, Sweden, with an annual incidence of 19.2 (range 3.7-37.4) per 100,000 inhabitants. Voles are considered to be both the main reservoir and the vector of PUU virus. A total of 3,591 rodents (mainly Clethrionomys glareolus, C. rufocanus, and Microtus agrestis) trapped in Vasterbotten between 1979 and 1987 were tested for the presence of PUU virus antibodies by enzyme-linked immunosorbent assay. The predominant species, C. glareolus (71% [2,544 of 3,591]), also had the highest antibody prevalence (19% [483 of 2,544]). In C. glareolus, the antibody prevalence rate increased with weight (age), reaching more than 50% in the heaviest weight group, and suggesting that horizontal infection may be important. The highest frequency (25%) of antibody-positive C. rufocanus was also found in the highest weight groups. Microtus agrestis showed low absolute numbers and a low antibody prevalence rate (5%). In C. glareolus, both antibody prevalence and weight were recurrently higher in the spring than in the previous fall. The antibody prevalence rate in spring was positively correlated with the vole density in the previous fall and spring. The fall antibody prevalence rate was directly dependent on C. glareolus density. The incidence of human NE in the fall was dependent on the concurrent density of C. glareolus, whereas the incidence of NE in the spring was dependent on vole density the previous fall.

Animals↗
PubMed1994

Hemorrhagic fever with renal syndrome: a study of sequelae following nephropathia epidemica.

Sequelae following Nephropathia epidemica (NE) were investigated in 792 individuals living in an endemic area of Sweden. Volunteers were tested for presence of Puumala (PUU) virus specific IgG antibodies in serum, as well as several parameters linked with renal dysfunction and cardiovascular disease (systolic and diastolic blood pressure, ECG, BMI, total cholesterol and serum creatinine). No differences were seen in any of the variables tested between PUU virus antibody positive (n = 110) and negative individuals (n = 682). In addition, the blood pressure was measured in 62 serologically confirmed patients diagnosed with clinical NE 2-6 years previously. One patient with moderate hypertension was found.

Adult↗
PubMed1994

Development of specific antibody patterns and clinical symptoms following Ockelbo virus infection.

Sixteen patients with symptoms typical for Ockelbo disease (rash, arthralgia, fever) were enrolled in a 2 1/2 year study, during which clinical symptoms were recorded and ELISA was employed to study specific IgM, IgG and IgG subclass development. Initially, all patients presented with rash and arthralgia, and five patients still suffered from joint symptoms at the end of the study period. Ockelbo virus specific IgM was detected during the first week post onset in 6 patients and in 15 patients by day 14. One patient failed to develop specific IgM and was later diagnosed with a human parvovirus B19 infection. All patients were IgM-negative 2 1/2 years post onset. Seroconversions or significant titer rises for specific total IgG were seen in 15 patients. IgG titers generally peaked within one year but in two patients maximum titers were seen 2 1/2 years post onset. Development of IgG1 followed that of total IgG, while IgG3, after an initial increase in all Ockelbo disease patients, remained at peak levels for one year in four patients, three of whom still had detectable IgG3 at the end of the study period. Ockelbo virus specific IgG2 or IgG4 was not detected in any of the patients.

Adult↗
PubMed1993

Anti-idiotypic antibodies against Puumala virus glycoprotein-specific monoclonal antibodies inhibit virus infection in cell cultures.

Rabbit anti-idiotypic antibodies (anti-ids) were generated against three bank vole and one human monoclonal antibody (MAb) specific for the two envelope glycoproteins of Puumala virus (G1 and G2). The anti-ids were purified by sequential immunoaffinity chromatography. Each anti-id inhibited the antigen binding of its respective MAb in a competitive ELISA. This inhibition, and the absence of cross-reactivity among the anti-ids for heterologous MAbs, showed that they all were specific for unique determinants on the antigen binding site of the homologous MAb. The anti-ids reacted with non-infected Vero E6 cells when examined by immunofluorescence and ELISA, indicating the presence of antibodies that mimic epitopes on the virus. Preincubation of Vero E6 cells with two of the anti-ids produced against neutralizing MAbs inhibited Puumala virus infection, suggesting that these two anti-ids blocked a cellular component involved in virus infection.

Animals↗
PubMed1993

The humoral response to Puumala virus infection (nephropathia epidemica) investigated by viral protein specific immunoassays.

Enzyme-linked immunosorbent assays for determination of antibodies directed to the nucleocapsid protein (N) or to either of the two envelope glycoproteins (G1 and G2) of Puumala virus were designed and evaluated. The assays were proven to be entirely restricted for each viral structural protein by biotin-labelled monoclonal antibodies. Sera from sequentially bled nephropathia epidemica patients (acute, convalescent, and 2-year sera) and sera from 10-20 year convalescents were examined for antibody specificity. All but one (n = 19) acute phase sera were shown to contain IgM antibodies directed to all three viral proteins. In the convalescent specimens the proportions of IgM to the different viral components were similar, but lower, when compared to the acute samples. Low levels of IgM against N and G2 were found in two out of ten 2-year sera. No virus-specific IgM were detected in sera drawn 10-20 years after infection. IgG antibodies to all three viral proteins were detected in all except one acute phase serum. The IgG response initially increased more rapidly to N, as compared to the anti-glycoprotein responses. The levels of glycoprotein-specific IgG were considerably increased 2 years after the disease, when compared to the levels detected in the convalescent specimens. The levels and specificities of IgG in very late convalescent sera (drawn 10-20 years after disease) resembled those detected 2 years after infection.

Animals↗
PubMed1993

Neutralizing human monoclonal antibodies against Puumala virus, causative agent of nephropathia epidemica: a novel method using antigen-coated magnetic beads for specific B cell isolation.

Human monoclonal antibodies (MAbs) against Puumala (PUU) virus were generated and characterized. Human spleen B lymphocytes were preselected for specific surface immunoglobulin (Ig) using magnetic beads coated with the viral glycoproteins, and subsequently immortalized by Epstein-Barr virus transformation. Four IgG-positive monoclonal lymphoblastoid cell lines (LCLs) were established and have remained stable MAb secretors for over 12 months. Analyses of the antigen and epitope specificities recognized by the MAbs showed overlapping binding patterns of four anti-glycoprotein 2-specific clones. Identical isotypes (IgGl lambda) and isoelectric points (9.2) of the four MAbs suggested that they were derived from the same original clone. The MAbs reacted with eight PUU virus-like strains, but were negative for Hantaan, Seoul, and Prospect Hill viruses in an immunofluorescence assay, indicating binding to a conserved epitope unique for strains associated with the European form of haemorrhagic fever with renal syndrome, nephropathia epidemica. The MAbs neutralized all investigated PUU virus-like strains in a focus reduction neutralization test. The MAb neutralizing activity was significantly enhanced in the presence of human or guinea-pig complement. To stabilize and increase antibody secretion and to reduce the demand for culture medium supplements (e.g. fetal calf serum), three of the monoclonal LCLs were fused with the non-secreting human x mouse partner SPAM-8. Several of the established human x (human x mouse) monoclonal triomas grew faster and produced larger amounts of MAbs when compared with the original LCLs.

Animals↗
PubMed1993

Contact allergy to a fatty acid ester component of cutting fluids.

6 patients employed in the metalworking industry developed a hand dermatitis after exposure to a vegetable-oil-based cutting fluid. After thorough investigation, including patch testing with components in the cutting fluid as well as an oil and cutting fluid series, contact allergy was demonstrated to a fatty acid ester EM-550 in the cutting fluid.

Adult↗
PubMed1993

Contact allergy to Duraphat.

Skin-sensitizing rosin is present in Duraphat, a fluoride varnish used all over the world. Two cases of hypersensitivity to Duraphat are presented: a dental nurse with dermatitis of the hand and a patient with allergic contact stomatitis.

Dermatitis, Allergic Contact↗