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Biomedical subjects

Gunnel Lindegren

Publications and source records attributed to Gunnel Lindegren.

3 recordsLinked to original sources

DNA microarray technique for detection and identification of seven flaviviruses pathogenic for man.

A flavivirus microarray was developed for detection and identification of yellow fever (YF), West Nile, Japanese encephalitis (JE), and the dengue 1-4 viruses, which are causing severe human disease all over the world. The microarray was based on 500-nucleotide probe fragments from five different parts of the seven viral genomes. A low-stringent amplification method targeting the corresponding regions of the viral genomic RNA was developed and combined with hybridization to the microarray for detection and identification. For distinction of the generated virus-specific fluorescence-patterns a fitting analysis procedure was adapted. The method was verified as functional for all seven flaviviruses and the strategy for the amplification, combined with the long probes, provided a high tolerance for smaller genetic variability, most suitable for these rapidly changing RNA viruses. A potentially high detection and identification capacity was proven on diverged strains of West Nile and dengue viruses. The lower limit for detection was equivalent, or better, when compared to routinely used RT-PCR methods. The performance of the method was verified on human patient samples containing dengue viruses, or normal human serum spiked with YF or JE viruses. The results demonstrated the ability of the flavivirus microarray to screen simultaneously a sample for several viruses in parallel, in combination with a good lower limit of detection.

Antibodies, Viral↗

Optimized diagnosis of acute dengue fever in Swedish travelers by a combination of reverse transcription-PCR and immunoglobulin M detection.

The dengue viruses (genus Flavivirus, family Flaviviridae) are mosquito borne and cause 100 million cases of dengue fever each year in most tropical and subtropical areas of the world. Increased global travel has been accompanied by an increased import not only of dengue but also of severe fevers of unknown origin to Sweden. Fifty-seven Swedish travelers to dengue epidemic areas, with clinical and serologically diagnosed dengue fever, were included in this study. To find fast and reliable methods to diagnose dengue in the early phase of the disease, patient acute-phase sera were investigated for the presence of dengue-specific immunoglobulin M (IgM) antibodies by enzyme-linked immunosorbent assay (ELISA) and also for dengue serotype (DEN-1 to DEN-4)-specific RNA by different PCR assays. The results showed that 15/20 (75%) of the samples collected 5 days or later post onset of disease, but only 5/37 (14%) of the samples collected on days 0 to 4, contained dengue-specific IgM. Of the samples collected on days 0 to 4 post onset, dengue RNAs of subtypes 1, 2, and 3 were detected by multiplex and/or by TaqMan PCR in 29/37 (78%); of these PCR-positive samples, 93% (27/29) were found IgM negative. By a combination of IgM ELISA and PCR assays, 84% (48/57) of the acute-phase samples were found to be positive. Our results demonstrated that detection of dengue viral RNA by reverse transcription-PCR and Taq-Man PCR is an excellent tool for the early diagnoses of dengue fever and that the IgM assay is a reliable complement for samples collected from day 5 post onset.

Acute Disease↗

Hantaviruses in Estonia.

Human serum samples collected from healthy individuals in 14 counties were screened by ELISA in order to investigate the presence of hantavirus infections in Estonia. Out of 1,234 serum samples, 124 were found positive for hantavirus-specific IgG and were subsequently serotyped by a focus reduction neutralization test. A total of 112 samples neutralized at least one of the examined hantaviruses-Puumala (PUUV), Saaremaa (SAAV), Dobrava (DOBV), Hantaan, and Seoul viruses-and thereby, the focus reduction neutralization test confirmed the overall hantavirus seroprevalence rate in Estonia to be 9.1%. Most of the sera showed a specific reaction (at least 4-fold higher endpoint titer) of neutralizing antibodies to PUUV (5.1%), while 3.4% showed a SAAV- or SAAV/DOBV-specific reaction. The fact that seven sera (0.6%) could not be serotyped may indicate the presence of an unknown hantavirus serotype. Hantavirus infections were confirmed in 13 of 14 investigated counties, with highly varying seroprevalence rates (1.0-28.4%). The sex ratio was 1.8:1.0 (M:F), and the antibody prevalence peaked in the age group 45-54 years. A total of 513 rodents of seven species trapped in seven counties were examined for the presence of hantavirus antigen, in order to study the distribution of hantavirus natural carriers. Two species, Clethrionomys glareolus and Apodemus agrarius, were found positive for hantaviral antigen in 13.7% and 4.5% of the investigated rodents, respectively. Analyses of viral sequences recovered from infected C. glareolus tissue samples showed that the infecting virus belonged to the PUUV genotype, confirming that PUUV circulates in mainland Estonia. The Estonian PUUV strains were placed in the closest proximity to Russian PUUV strains in phylogenetic trees, suggesting a common evolutionary history. Together with earlier data on SAAV in A. agrarius, the results revealed that two hantaviruses, PUUV and SAAV, are common in Estonia and that the incidence of human infection is high in both cases.

Animals↗