Elisabeth Daghofer

Identification of Different States of Hepatitis B Virus Infection with a Quantitative PCR Assay

ABSTRACT The level of hepatitis B virus (HBV) DNA in serum reflects the replicative activity of HBV. To compare serum HBV DNA levels in different states of hepatitis B, 47 sera of patients with HBeAg-positive chronic hepatitis B, 4 sera of patients with HBeAg-negative chronic hepatitis B, 40 samples of patients after HBeAg seroconversion during alpha interferon treatment, 57 sera of inactive HBsAg carriers, and 42 sera of patients who had recovered from chronic hepatitis B more than 12 months prior to blood collection were checked for the presence of HBV DNA with the Amplicor HBV Monitor Test. In patients with HBeAg-positive chronic hepatitis B, the median of serum HBV DNA levels (8.3 × 108 copies/ml) was significantly higher than that for patients after HBeAg seroconversion (6.2 × 103 copies/ml) and than that for inactive HBsAg carriers (5.6 × 103 copies/ml). None of the patients who had recovered from hepatitis B had detectable HBV DNA in serum. Quantitative PCR proved to be a valuable tool for identification of different states of HBV infection. This technique was found to be a good method for determination of serum HBV DNA levels both for patients with HBeAg seroconversion and for inactive carriers who showed low viremia not detectable by conventional hybridization assays.

Rapid detection of enterovirus infection by automated RNA extraction and real-time fluorescence PCR

BACKGROUND Molecular detection has been shown to be superior to tissue culture for the detection of enteroviruses in cerebrospinal fluid (CSF) specimens. OBJECTIVES In this study, a qualitative molecular assay based on automated RNA extraction with the MagNA Pure LC and real-time PCR on the LightCycler (LC) instrument was evaluated and compared with an in-house molecular assay. STUDY DESIGN A total of 109 CSF specimens were investigated for the comparative study. The detection limit of the new molecular assay was determined with 10-fold dilutions of two enterovirus strains and with the Third European Union Concerted Action Enterovirus Proficiency Panel. RESULTS With the enterovirus strains, the detection limit of the LC assay was found to be 0.1 TCID(50) (50% tissue culture infective dose). When samples of the Third European Union Concerted Action Enterovirus Proficiency Panel were tested, both molecular assays gave identical results to the expected results, which were based upon the results of three reference laboratories using a total of four different molecular methods before distribution of the panel. When clinical specimens were tested, there was a correlation between the LC assay and the in-house assay in 105 of 109 cerebrospinal fluids. CONCLUSIONS The new molecular assay allows rapid detection of enterovirus RNA in CSF. It was found to be labor saving and showed sufficient sensitivity.

Evaluation of an Automated Sample Preparation Protocol for Quantitative Detection of Hepatitis C Virus RNA

ABSTRACT The COBAS AMPLIPREP instrument for automated sample preparation has recently been introduced. In this study, the COBAS AMPLIPREP/COBAS AMPLICOR HCV MONITOR test, which includes this new molecular device, was evaluated and compared to the COBAS AMPLICOR HCV MONITOR test, which includes a manual extraction protocol. Interassay and intra-assay variation, precision, and linearity were determined, and a total of 130 clinical specimens were investigated. For determination of interassay variation, coefficients of variation were found to be between 9 and 59% for the COBAS AMPLIPREP/COBAS AMPLICOR HCV MONITOR test and between 13 and 69% for the COBAS AMPLICOR HCV MONITOR test. For determination of intra-assay variation, coefficients of variation were found to be between 7 and 13% for the COBAS AMPLIPREP/COBAS AMPLICOR HCV MONITOR test and between 8 and 16% for the COBAS AMPLICOR HCV MONITOR test. When precision of the COBAS AMPLIPREP/COBAS AMPLICOR HCV MONITOR test was tested, all results were found to be within ±0.5 log of the expected results. Determination of linearity resulted in a quasilinear curve over 3 logs. When clinical samples were tested with the COBAS AMPLIPREP/COBAS AMPLICOR HCV MONITOR test and compared with the COBAS AMPLICOR HCV MONITOR test, all results were found within ±0.5 log. In conclusion, the assay, which included the new molecular device, proved to be suitable for the routine molecular laboratory. It was found to be laborsaving and easy to handle.

Effects of Storage and Type of Blood Collection Tubes on Hepatitis C Virus Level in Whole Blood Samples

ABSTRACT In this study, we compared serum hepatitis C virus (HCV) RNA concentrations with HCV RNA concentrations in whole blood collection tubes, including two different types of EDTA tubes and nucleic acid stabilization tubes (NASTs). We also investigated the impact of a processing delay on HCV RNA concentration in these tubes. In NASTs, the mean HCV RNA concentration was comparable to the mean serum HCV RNA concentration at “date zero.” In EDTA tubes, mean baseline HCV RNA concentrations were higher. Storage at room temperature up to 96 h did not result in a decline of HCV RNA concentration in any of the whole blood collection tubes. In NASTs, HCV RNA concentrations remained stable during the whole study period, whereas a significant increase of HCV RNA was observed in both types of EDTA tubes at 96 h compared to date zero. We concluded that HCV RNA remains stable in NASTs at room temperature for at least 96 h, allowing greater flexibility in sample collection and transport.

Semiautomated Quantification of Hepatitis B Virus DNA in a Routine Diagnostic Laboratory

ABSTRACT The Cobas Amplicor HBV Monitor test for quantitative determination of hepatitis B virus (HBV) DNA in serum has recently been introduced. To evaluate the performance of this assay in a routine diagnostic laboratory, reproducibility of results was determined with the First European Union Concerted Action HBV Proficiency Panel and the Accurun 325 HBV DNA Positive Control, Series 300. Results for 270 routine serum samples were additionally evaluated. To avoid the retesting of a large number of samples due to titers exceeding the upper limit for the linear range of the assay, sera of patients with chronic hepatitis B (CHB) were diluted prior to the assay to 10−4 in normal human plasma, which is included in the assay. The mean coefficient of variation was 22.9% for all input HBV DNAs. Of 270 routine serum samples, 182 (150 sera from transplant donors and 32 sera from patients who had recovered from CHB) tested negative. Eighty-six sera were found to be HBV DNA positive; in six sera, HBV DNA levels were found to exceed the upper limit for the linear range of the assay and had to be retested. In the remaining two sera, inhibition occurred. The semiautomated Cobas Amplicor HBV Monitor test showed sufficient reproducibility and helped in avoiding human error. The relatively narrow linear range of detection is a limitation of the new assay.

Fully Automated Detection of Hepatitis C Virus RNA in Serum and Whole-Blood Samples

ABSTRACT In this study, we established a fully automated molecular assay for qualitative detection of hepatitis C virus (HCV) in serum and whole-blood samples and compared it with conventional molecular assays, including manual HCV RNA extraction protocols. Whole-blood samples were collected from patients with and without chronic HCV infection in EDTA tubes and nucleic acid stabilization tubes (NASTs). Prior to HCV RNA extraction, the HCV Internal Control (IC), derived from the COBAS AMPLICOR HCV test, version 2.0 (Roche Molecular Diagnostics), was added. The new assay was based on an automated extraction protocol on the MagNA Pure LC instrument (Roche Applied Science), followed by automated reverse transcription, amplification, hybridization, and detection on the Cobas Amplicor analyzer (Roche Molecular Diagnostics). The detection limit of the new assay was found to be similar to those of conventional molecular assays. In clinical samples, 100% agreement between the new assay and conventional methods was observed. The introduced amount of IC was detected in 45 of 45 serum samples, 41 of 45 EDTA tube whole-blood samples, and 43 of 45 NAST whole-blood samples. Retesting led to more frequent IC detection. The fully automated molecular assay was found to be suitable for detection of HCV RNA in different kinds of sample materials. It may be recommended for use in the high-throughput routine molecular diagnostic laboratory.

Determination of Human Immunodeficiency Virus Type 1 Subtypes by a Rapid Method Useful for the Routine Diagnostic Laboratory

ABSTRACT The existence of human immunodeficiency virus type 1 (HIV-1) subtypes has many important implications for the global evolution of HIV and for the evaluation of pathogenicity, transmissibility, and candidate HIV vaccines. The aim of this study was to establish a rapid method for determination of HIV-1 subtypes useful for a routine diagnostic laboratory and to investigate the distribution of HIV-1 subtypes in Austrian patients. Samples were tested by a subtyping method based on a 1.3-kb sequence of the polymerase gene generated by a commercially available drug resistance assay. The generated sequence was subtyped by means of an HIV sequence database. Results of 74 routine samples revealed subtype B (71.6%) as the predominant subtype, followed by subtype A (13.5%) and subtype C (6.8%). Subtypes E, F, G, and AE (CM240) were also detected. This subtyping method was found to be very easy to handle, rapid, and inexpensive and has proved suitable for high-throughput routine diagnostic laboratories. The specific polymerase gene sequence, however, must be existent.

Reliability of the Siemens Enzygnost and Novagnost Epstein–Barr Virus assays for routine laboratory diagnosis: agreement with clinical diagnosis and comparison with the Merifluor Epstein–Barr Virus immunofluorescence assay

BackgroundDiagnosis of Epstein–Barr virus (EBV) infection is routinely conducted by clinical laboratories, especially to diagnose infectious mononucleosis. At an estimated general population incidence of 1:200, this represents a potentially significant testing burden. We evaluated the reliability of the Siemens Novagnost® and Enzygnost® EBV microtiter assays measuring VCA IgM and IgG, and EBNA-1 IgG for clinical diagnosis of EBV-related infectious mononucleosis.MethodsRemnant sera from 537 patients tested for EBV infection were used to compare the Siemens assays to each other and to the Merifluor assay. The Siemens assays are qualitative/semiquantitative, automatable enzyme immunoassays. The Merifluor assays are manual, qualitative indirect immunofluorescent assays. Testing was conducted on the Siemens and Merifluor assays in parallel. All assays were conducted and interpreted according to each manufacturer’s specifications. Agreement of serostatus between each of the three assays was assessed. Discrepant results were resolved using a third method (Mikrogen recomLine).ResultsFinal EBV serostatus indicated 2.9% of the population had an acute infection, 89.6% had a past infection, and 7.5% were EBV naive. All three assays demonstrated 100% agreement with acute infection. Agreement with past-infection serostatus was 99.1% for Enzygnost, between 86% and 98.8% for Novagnost, and 98.1% for Merifluor. Seronegative agreement was 100% for Enzygnost, 89.7% for Novagnost, and 92.3% for Merifluor.ConclusionsThe Siemens Enzygnost and Novagnost EBV microtiter assays are suitable for clinical rule-in of acute EBV infection and for identifying EBV-naive individuals. Both assays also adequately identify remote EBV infections. Because these assays can be automated, they can improve speed and efficiency of EBV testing, especially in high-volume laboratories.

HHV-6 infection – not only tertian fever

The primary infection with the human herpesvirus (HHV) 6 usually occurs before the age of two (95%) and clinically either presents as tertian fever followed by exanthem subitum (10%) or even more often as febrile disease without an exanthem. In adults an active HHV‐6 infection can present as febrile illness. A 19‐year‐old immunocompetent patient presented with high fever, exanthem, swelling of the lymph nodes and pancytopenia and was serologically diagnosed as active HHV‐6 infection with anti‐ HHV‐6‐IgM‐ and ‐IgG antibodies. Since the antibodies were already detectable on day 5 of disease, with persistence of high IgG and undetectable IgM after 4 weeks, a reactivation seemed most likely. There was no evidence for an underlying immunosuppressive disease or reactivation induced by viral co‐infection. Fulminant hepatitis or meningoencephalitis are the most frequent complications in immunocompetent individuals and have to be recognized at an early stage.