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Matthias Niedrig

Publications and source records attributed to Matthias Niedrig.

32 records · Page 2Linked to original sources
PubMed2004

First international quality assurance study on the rapid detection of viral agents of bioterrorism.

We have conducted an international quality assurance study of filovirus, Lassa virus, and orthopox virus PCR with 24 participants. Of the participating laboratories, 45.8 and 66.7% detected virus in all plasma samples, which contained > or = 5,000 and > or = 100,000 copies per ml, respectively. Sensitivity levels were not significantly different between viruses. False-negative results were attributable to a lack of sensitivity.

Bioterrorism↗
PubMed2004

Real-time PCR system for detection of orthopoxviruses and simultaneous identification of smallpox virus.

A screening assay for real-time LightCycler (Roche Applied Science, Mannheim, Germany) PCR identification of smallpox virus DNA was developed and compiled in a kit system under good manufacturing practice conditions with standardized reagents. In search of a sequence region unique to smallpox virus, the nucleotide sequence of the 14-kDa fusion protein gene of each of 14 variola virus isolates of the Russian World Health Organization smallpox virus repository was determined and compared to published sequences. PCR primers were designed to detect all Eurasian-African species of the genus ORTHOPOXVIRUS: A single nucleotide mismatch resulting in a unique amino acid substitution in smallpox virus was used to design a hybridization probe pair with a specific sensor probe that allows reliable differentiation of smallpox virus from other orthopoxviruses by melting-curve analysis. The applicability was demonstrated by successful amplification of 120 strains belonging to the orthopoxvirus species variola, vaccinia, camelpox, mousepox, cowpox, and monkeypox virus. The melting temperatures (T(m)s) determined for 46 strains of variola virus (T(m)s, 55.9 to 57.8 degrees C) differed significantly (P = 0.005) from those obtained for 11 strains of vaccinia virus (T(m)s, 61.7 to 62.7 degrees C), 15 strains of monkeypox virus (T(m)s, 61.9 to 62.2 degrees C), 40 strains of cowpox virus (T(m)s, 61.3 to 63.7 degrees C), 8 strains of mousepox virus (T(m), 61.9 degrees C), and 8 strains of camelpox virus (T(m)s, 64.0 to 65.0 degrees C). As most of the smallpox virus samples were derived from infected cell cultures and tissues, smallpox virus DNA could be detected in a background of human DNA. By applying probit regression analysis, the analytical sensitivity was determined to be 4 copies of smallpox virus target DNA per sample. The DNAs of several human herpesviruses as well as poxviruses other than orthopoxviruses were not detected by this method. The assay proved to be a reliable technique for the detection of orthopoxviruses, with the advantage that it can simultaneously identify variola virus.

Animals↗
PubMed2004

Frequent detection of viral nucleic acids in heart valve tissue.

Due to a paucity of published data concerning the prevalence of viral nucleic acid in homografts, we analyzed tissue from 30 donor hearts for the presence of viral genome sequences of enteroviruses, adenoviruses, human cytomegalovirus, and influenza virus using different PCR techniques. Viral DNA was amplified in 64 and 52% of the subvalvular myocardial tissue and non-coronary valve samples, respectively. These findings, compared with clinical history and histologic and serologic analysis, demonstrate the importance of viral safety measures in heart valve banking.

Adolescent↗
PubMed2004

S protein of severe acute respiratory syndrome-associated coronavirus mediates entry into hepatoma cell lines and is targeted by neutralizing antibodies in infected patients.

The severe acute respiratory syndrome-associated coronavirus (SARS-CoV) causes severe pneumonia with a fatal outcome in approximately 10% of patients. SARS-CoV is not closely related to other coronaviruses but shares a similar genome organization. Entry of coronaviruses into target cells is mediated by the viral S protein. We functionally analyzed SARS-CoV S using pseudotyped lentiviral particles (pseudotypes). The SARS-CoV S protein was found to be expressed at the cell surface upon transient transfection. Coexpression of SARS-CoV S with human immunodeficiency virus-based reporter constructs yielded viruses that were infectious for a range of cell lines. Most notably, viral pseudotypes harboring SARS-CoV S infected hepatoma cell lines but not T- and B-cell lines. Infection of the hepatoma cell line Huh-7 was also observed with replication-competent SARS-CoV, indicating that hepatocytes might be targeted by SARS-CoV in vivo. Inhibition of vacuolar acidification impaired infection by SARS-CoV S-bearing pseudotypes, indicating that S-mediated entry requires low pH. Finally, infection by SARS-CoV S pseudotypes but not by vesicular stomatitis virus G pseudotypes was efficiently inhibited by a rabbit serum raised against SARS-CoV particles and by sera from SARS patients, demonstrating that SARS-CoV S is a target for neutralizing antibodies and that such antibodies are generated in SARS-CoV-infected patients. Our results show that viral pseudotyping can be employed for the analysis of SARS-CoV S function. Moreover, we provide evidence that SARS-CoV infection might not be limited to lung tissue and can be inhibited by the humoral immune response in infected patients.

Animals↗
PubMed2004

SARS coronavirus detection.

We developed a set of three real-time reverse transcription-polymerase chain reaction (PCR) assays that amplify three different regions of the SARS-associated coronavirus (SARS-CoV), can be run in parallel or in a single tube, and can detect <10 genome equivalents of SARS-CoV. The assays consider all currently available SARS-CoV sequences and are optimized for two prominent real-time PCR platforms.

Humans↗
PubMed2004

SARS molecular detection external quality assurance.

Inactivated severe acute respiratory syndrome-associated coronavirus samples were used for an external quality assurance study within the World Health Organization SARS Reference and Verification Network and other reference institutions. Of 58 participants, 51 correctly detected virus in all samples > or =9,400 RNA copies per milliliter and none in negative samples. Commercial test kits significantly improved the outcome.

Humans↗
PubMed2003

Detection of yellow fever virus: a comparison of quantitative real-time PCR and plaque assay.

Yellow fever virus quantitation is performed routinely by cultivation of virus containing samples using susceptible cells. Counting of the resulting plaques provides a marker for the number of infectious particles present in the sample. This assay usually takes up to 5 days before results are obtained and must be carried out under L2 or L3 laboratory conditions, depending on the yellow fever virus strain used. For clinical diagnosis of yellow fever virus infections the cell culture-based approach takes too long and is of limited practical relevance. Recently, due to its considerable sensitivity, PCR has become a promising method for virus detection. However, whilst PCR can detect virus-specific nucleic acids, it does not allow conclusions to be drawn regarding the infectious potential of the virus detected. Nonetheless, for diagnostic purposes, a rapid, specific and sensitive virus PCR is preferable. Therefore, two independent yellow fever virus-specific real-time PCR assays were established and compared the viral RNA loads to the results of a traditional plaque assay. The estimated ratio of yellow fever virus genomes to infectious particles was between 1000:1 and 5000:1; both approaches displayed a comparable precision of <45%. A significant correlation between genome number as determined by real-time PCR and the corresponding number of plaques in paired samples was found with a Pearson coefficient of correlation of r=0.88 (P<0.0001).

Animals↗
PubMed2003

Characterisation of human tick-borne encephalitis virus from Sweden.

Viruses of the tick-borne encephalitis (TBE) antigenic complex, within the family Flaviviridae, cause a variety of diseases including uncomplicated febrile illness, meningo-encephalitis and haemorrhagic fever. Different wildlife species act as reservoir hosts with ixodid tick species as vectors. TBE virus (TBEV) causes 40-130 cases confirmed serologically in Sweden each year. Characteristics of TBEV strains circulating in Sweden have not been investigated previously and no viral sequence data has been reported. In the present study, virus strains were isolated from serum of patients with clinical symptoms consistent with acute TBEV infection. Serologic characterisation, using a panel of E-specific monoclonal antibodies and cross-neutralisation tests, indicated that the Swedish strains of TBEV, isolated 1958-1994, all belonged to the Western TBEV subtype, which includes the Austrian vaccine strain Neudoerfl. Genetic analysis of a partial E-sequence confirmed this close relationship: all Swedish TBEV strains belonged to the European lineage of the Western TBEV subtype, which includes the previously characterised strains Neudoerfl, Hypr, and Kumlinge. Further, three Swedish strains showed partial E-sequences identical to that of the Finnish Kumlinge strain, ten Swedish strains formed a well-supported separate cluster, whereas four others did not show any real clustering. No apparent correlation was observed in comparison of clinical parameters with genetic data or geographic origin of the strains.

Adolescent↗
PubMed2003

Quality control measures for the serological diagnosis of hantavirus infections.

BACKGROUND: With society's rapidly increasing mobility, patients infected with severe viral infections can become seriously ill at any place in Europe and elsewhere. Improving the diagnostics of these infections is the most important step in detecting the pathogens and dealing with them, and for this purpose, quality control measures are essential tools. OBJECTIVES: To assess the diagnostic reality for rare hantavirus infections in Europe by (1) running a pre-evaluation panel (four samples, sent out in 1999) to optimise sample preparation and shipping procedure and afterwards (2) starting an External Quality Assurance (EQA) program (20 samples, sent out in 2001). STUDY DESIGN: All samples sent out had to be tested for the presence of specific IgG and IgM antibodies against hantavirus. For the pre-evaluation panel, four samples were distributed (two samples IgG+/IgM-, one sample IgG-borderline/IgM-, one sample IgG-/IgM-), for the EQA 20 samples (six samples IgG+/IgM+, eight samples IgG+/IgM-, one sample IgG-borderline/IgM-, five samples IgG-/IgM-). Thirteen laboratories took part in the pre-evaluation panel, 18 laboratories participated in the first EQA run. RESULTS: For the pre-evaluation panel, the participants reported correct results for 64% of the IgG-positive samples (85% excluding borderline-positive sample), and 92% for the IgG-negative sample. IgM testing was correctly negative in all laboratories. For the EQA, the participants reported correct results for 76% of the IgG-positive samples, and 97% correct results for the IgG-negative samples. For the IgM-positive samples, 53% correct results were reported, and 98% correct results for the IgM-negative samples. CONCLUSIONS: The results presented here prove the importance of quality measures also for viruses only rarely suspected, like hantavirus, and they clearly demonstrate the need for improvement of the existing test systems.

Antibodies, Viral↗
PubMed2003

Clinical and laboratory features of dengue virus-infected travellers previously vaccinated against yellow fever.

Dengue is a mosquito-borne viral infection endemic throughout the tropics and subtropics. The global prevalence of dengue has grown dramatically in recent years and it has become a major international public health concern. The close taxonomic relationships between yellow fever and dengue viruses gave rise to concerns that previous vaccination against yellow fever could modify the course of dengue infection and contribute to the development of dengue haemorrhagic fever/dengue shock syndrome (DHF/DSS). This study reports the clinical and laboratory features of dengue virus-infected travellers previously vaccinated against yellow fever.

Adult↗
PubMed2003

Diagnosis of tick-borne encephalitis by a mu-capture immunoglobulin M-enzyme immunoassay based on secreted recombinant antigen produced in insect cells.

Acute tick-borne encephalitis is diagnosed by detection of IgM antibodies to tick-borne encephalitis virus (TBEV) (genus Flavivirus) in patient serum. TBEV membrane (M) and envelope (E) proteins have previously been shown to form virus-like particles when expressed in mammalian cells. We expressed the prM/M and E proteins in insect cells with a recombinant baculovirus system and obtained antigenic protein secreted into the cell culture medium, as evidenced by detection by a panel of five monoclonal antibodies to TBEV E protein. According to the sedimentation pattern in sucrose gradient centrifugation, the proteins were most likely secreted as virus-like particles. A mu-capture immunoglobulin M-enzyme immunoassay (IgM-EIA) test was developed and compared to a commercially available TBEV-IgM test (Progen) based on inactivated purified TBEVs. With a panel of 100 TBEV-IgM-negative, 50 TBEV-IgM-positive, and seven dengue virus-IgM-positive serum samples from our diagnostic laboratory, a sensitivity of 100% and specificity of 99% were obtained, and the correlation coefficient of EIA absorbances with the reference test was 0.93. The antigen was also suitable for IgG antibody detection in an immunofluorescent assay format. This is the first time that secreted, fully antigenic E protein has been produced in insect cells for this arthropod-borne flavivirus.

Animals↗
PubMed2003

Type 1 diabetes in Swedish bank voles (Clethrionomys glareolus): signs of disease in both colonized and wild cyclic populations at peak density.

Colonized bank voles (Clethrionomys glareolus) originating from Sweden developed type 1 diabetes. Animals became polydipsic, glucosuric, and hyperglycemic and gradually developed a lethal ketoacidosis. Pancreas in animals with end-stage disease showed total destruction of islet cells. Interestingly, also a high proportion of wild bank voles in cyclic populations that were trapped at (or close to) the cyclic population density peak frequently showed high blood glucose levels and pathological glucose tolerance test. Extensive islet destruction was not seen in wild bank voles at the time of capture, but did develop in some of the animals over a time period of two months. Diabetes in both colonized and wild bank voles was associated with Ljungan virus (LV). LV could be isolated from the pancreas of diabetic bank voles and antigen detected at the site of tissue damage by immunohistochemistry. In addition, picornavirus-like particles were visualized in the islets of diabetic voles using thin-section transmission electron microscopy.

Animals↗
PubMed2002

Reactivity of serum samples from patients with a flavivirus infection measured by immunofluorescence assay and ELISA.

Flavivirus infections are a significant public health problem, since several members of the Flaviviridae family are highly pathogenic to humans. Accurate diagnosis and differentiation of the infecting virus is important, especially in areas where many flaviviruses are circulating. In this study we evaluated a newly developed commercially available immunofluorescence assay (IFA) (INDX, Baltimore, MD, USA) for the detection of IgM and IgG antibodies against dengue virus, yellow fever virus, Japanese encephalitis virus and West Nile virus. IFA was compared with standard diagnostic enzyme immunoassays (EIAs) specific for the detection of IgM and IgG antibodies against these viruses. Forty-seven serum samples from patients with a defined flavivirus infection were tested. As controls, serum samples from individuals with antibodies against tick-borne encephalitis virus and hepatitis C virus as well as healthy individuals were included. The results obtained from this study indicate that IFA showed a significantly better discrimination for flavivirus specific IgM antibodies than did the standard IgM specific EIAs (the overall cross-reactivity varied between 4 and 10% by IFA and 30-44% by EIA for the respective viruses). In contrast, the detection of flavivirus specific IgG antibodies showed high cross-reactions in both IFA and EIAs (overall cross-reactivity 16-71 and 62-84%, respectively). This study clearly stated the complexity of flavivirus diagnosis, showing that one cannot rely on one assay or search for one virus only. The flavivirus IFA is a useful tool for the identification of flavivirus infections during the acute stage of disease. In particular, IFA can be an important diagnostic tool for testing samples from travellers who have been accidentally exposed to these viruses.

Antibodies, Viral↗