Storage conditions of blood samples and primer selection affect the yield of cDNA polymerase chain reaction products of hepatitis C virus

Occult Infection with Hepatitis C Virus: Looking for Clear-Cut Boundaries and Methodological Consensus

The sustained virologic response and elimination of HCV is widely viewed as a true cure of chronic hepatitis C as it associates with amelioration of histological liver damage and improved clinical outcomes. Therefore, the existence and clinical burden of occult HCV infection (OCI) has been a controversial issue for many years. In this review, we summarize recently published data that adds new information on the molecular and clinical background of OCI and its epidemiological significance. We also identify and discuss the most important methodological pitfalls, which can be a source of inconsistency between studies. Data that have accumulated so far, strongly support the existence of extrahepatic HCV replication in individuals negative for serum HCV-RNA by conventional clinical tests. OCI emerges as a condition where the immune system is unable to fully resolve infection but it is continuously stimulated by low levels of HCV antigens, leading to progression of liver pathology and extrahepatic HCV-related complications. Moreover, the development of monitoring strategies or management guidelines for OCI is still hampered by the lack of clear definition and the confusion regarding its clinical significance. Careful study design and the introduction of uniform protocols for the detection of low-level HCV-RNA are crucial for obtaining reliable data on OCI.

Development of a multiplex assay to measure the effects of shipping and storage conditions on the quality of RNA used in molecular assays for detection of viral haemorrhagic septicemia virus

Abstract In routine diagnostics, real-time reverse transcriptase quantitative PCR (RT-qPCR) has become a powerful method for fish health screening. Collection, transportation, and storage conditions of specimens could dramatically affect their integrity and could consequently affect RT-qPCR test results. In this study, to assess the expression profile of elongation factor 1 alpha (ELF-1α) gene, head kidney (HK) tissues from Atlantic Salmon Salmo salar were exposed at room temperature, 4°C, -20°C, and -80°C as well as in 70% ethanol for 6, 12, 24, 48, and 72 h. Data showed a significant increase of RT-qPCR cycle threshold (Ct) values for ELF-1α ranging from 14.7 to 26.5 cycles for tissues exposed to room temperature. In order to mimic the sample transportation conditions, different temperatures of storage were used and tissue quality was evaluated using ELF-1α gene expression. Data showed that Ct values for ELF-1α increased significantly when the tissues were transported on ice for 2 h, stored at -20°C, thawed on ice for 6 h, and stored again at -80°C. The HK tissues collected from Atlantic Salmon challenged with viral hemorrhagic septicemia virus (VHSV) through intraperitoneal injection were exposed at room temperature for 0, 6, 12, 24, 48, 72, and 96 h. Data showed a good correlation of values for ELF-1α and VHSV Ct although the ELF-1α mRNA of the host degraded faster than the RNA of VHSV. Based on these data, HK tissues could be transported on ice or ice packs without the quality of the tissue being affected when stored at -80°C upon arrival at the laboratory. In addition, 70% ethanol could be used as a preservative for long-distance transportation. For an efficient diagnostic test, a duplex VHSV-ELF-1α was developed and optimized. Data showed that the sensitivity of the duplex assay for VHSV was similar to the singleplex. Received November 25, 2013; accepted February 14, 2014.

SPIN: Development of sample-specific protein integrity numbers as an index of biospecimen quality

It is widely accepted that variable biorepository specimen handling conditions can significantly alter outcomes of clinical research studies, suggesting the need for a metric for sample analyte protein integrity. In line with the National Cancer Institute (NCI) Best Practices, it is vital that the integrity of specimens used for biomarker studies are of the highest standard to ensure validity of the data they generate and confidence in the application of new findings to clinical management. We describe the creation of a program to discover proteins in biorepository samples that can be utilized to assess the integrity of stored specimens for protein-based biomarker studies, similar to the universally accepted quality metric for RNA, the RNA Integrity Number, or RIN. The study mimics potential variation in pre-analytical conditions which may result in proteolysis and other proteome-associated changes and employs surface-enhanced laser desorption time-of-flight mass spectrometry (SELDI-TOF MS) to assess changes in multiple proteins and peptides in a high-throughput manner. Candidate peaks from SELDI spectra of representative sample types (e.g., serum, urine, tissue extracts) which demonstrate differing but reproducible sensitivity to suboptimal processing and storage were selected and quantified in a series of specimens stored in the BioBank within the Beaumont Health System. We then assigned a relative index known here as Sample-specific Protein Integrity Number, or SPIN, which is derived from a ratio of nonstable vs. stable proteins for each sample type in the investigation. This methodology can be applied to every sample type and, once refined and established, the SPIN could be used by any biobank or laboratory using biobanked samples without specialized equipment and irrespective of the sample pre-analytical collection conditions.

Stability of hepatitis C virus RNA in blood samples by TaqMan real-time PCR

The storage conditions of blood samples for reliable results are very important in hepatitis C virus (HCV) RNA amplification tests used in routine HCV analyses. According to many studies, storage conditions could affect the RNA stability for HCV RNA detection. We have studied HCV RNA stability in blood samples stored at 4 degrees C. Nineteen blood samples containing different HCV RNA levels were stored at 4 degrees C and they were then analyzed by TaqMAN real-time PCR method. HCV RNA levels remained almost stable (100%) at least for five weeks at this storage condition. However, among them, the stability period was up to 11 weeks in two of the samples. As with these findings, there was a slightly significant correlation between the positivity time and the beginning HCV RNA levels (r=0.474, P=0.040). We conclude that, blood samples can be stored at 4 degrees C for five weeks without any significant difference in detected HCV RNA level by using TaqMan real-time PCR.

Occult HCV infection: an unexpected finding in a population unselected for hepatic disease

Background

Occult Hepatitis C virus (HCV) infection is a new pathological entity characterized by presence of liver disease and absence or very low levels of detectable HCV-RNA in serum. Abnormal values of liver enzymes and presence of replicative HCV-RNA in peripheral blood mononuclear cells are also observed. Aim of the study was to evaluate occult HCV occurrence in a population unselected for hepatic disease.

Methodology/Principal Findings

We chose from previous epidemiological studies three series of subjects (n = 276, age range 40–65 years) unselected for hepatic disease. These subjects were tested for the presence of HCV antibodies and HCV-RNA in plasma and in the peripheral blood mononuclear cells (PBMCs) by using commercial systems. All subjects tested negative for HCV antibodies and plasma HCV-RNA and showed normal levels of liver enzymes; 9/276 patients (3.3%) were positive for HCV-RNA in PBMCs, identifying a subset of subjects with potential occult HCV infection. We could determine the HCV type for 8 of the 9 patients finding type 1a (3 patients), type 1b (2 patients), and type 2a (3 patients).

Conclusions

The results of this study show evidence that occult HCV infection may occur in a population unselected for hepatic disease. A potential risk of HCV infection spread by subjects harbouring occult HCV infection should be considered. Design of prospective studies focusing on the frequency of infection in the general population and on the clinical evolution of occult HCV infection will be needed to verify this unexpected finding.

Mathematical modeling of hepatitis C virus transmission in hemodialysis

BACKGROUND

A deterministic mathematical model is developed to explain nontransfusion nosocomial transmission of hepatitis C virus (HCV) from patient to patient during hemodialysis sessions.

METHODS

The model requires 4 sequential steps for cross-transmission: (1) The dialysis session contains at least 1 patient infected with HCV; (2) a hemodialysis staff member connects an uninfected patient to dialysis after having connected an infected patient; (3) the hemodialysis staff member does not change gloves between an infected patient and an uninfected patient; and (4) the uninfected patient is contaminated after exposure to the blood of an infected patient.

RESULTS

We tested the model by comparing observed incidences of HCV infection from epidemiologic studies with calculated incidences. Calculated incidences are closed to observed incidences. We assessed the impact of prevalence of HCV infection, no glove change between patients, and nurse:patient ratio on the incidence of HCV infection. We found linear relationships between incidence and prevalence and between incidence and no glove change, and an increasing logarithmic relationship between incidence and nurse:patient ratio.

CONCLUSION

Our model should be able to estimate the likely incidence of infection in hemodialysis centers. Compliance with recommended hand hygiene and glove use practices, especially glove changes between patients, is essential to prevent HCV infection in hemodialysis centers, particularly those with high HCV prevalence. Mathematical modeling can used as a tool for control.

Serum biobank certification and the establishment of quality controls for biological fluids: examples of serum biomarker stability after temperature variation

BACKGROUND

One of the main issues in biobanking is the establishment of standard operating procedures for specimen collection, preparation and storage to control for pre-analytical variation. For biological fluids such as serum, there is currently a lack of sensitive biomarkers for the quality control of cryopreservation conditions.

METHODS

The process approach was used to establish an ISO 9001:2000 quality management system. Immunoenzymatic and functional assays were used to assess the stability of the following candidate quality control biomarkers: secretory phospholipase A2, matrix metalloprotease 7, transforming growth factor beta1 and anti-HBs immunoglobulin.

RESULTS

Five product processes and their corresponding indicators were identified. In the preparation-aliquoting-storage process, no quality control indicator for serum was identified. Only matrix metalloprotease 7 showed moderate susceptibility to freeze-thaw cycles.

CONCLUSIONS

Biomarkers that have an on-off response to temperature variation could serve as quality indicators for the core processes of biobanking, which are the preparation and storage of biological fluids. The identification of such biomarkers is needed.

Stability of lyophilised specimens for the molecular detection of viral DNA/RNA

BACKGROUND

The range of nucleic acid-based technologies for the molecular detection of pathogens has grown rapidly in recent years. The influx of new testing methods into the clinical laboratory, demands for evaluation and standardisation of methods, interpretation of results and evaluation of laboratory performance have highlighted the need for internal and External Quality Assessment (EQA) systems more than ever before. External Quality Assessment panels demand reproducible, stable specimens of consistent form, suitable for transportation.

OBJECTIVES

To determine the stability of freeze-dried viral specimens in terms of molecular detection.

STUDY DESIGN

When EQA specimens are prepared, they undergo long-term storage and testing as part of the quality control (QC) process. The frequency and nature of testing is dependent on the resources and methodologies available at the time. A range of virus preparations used for EQA was monitored over a period of months to years in a retrospective study; the available quality monitoring data for the five viruses, including storage temperature and method of detection were analysed.

RESULTS

The nucleic acid (DNA or RNA) of the freeze-dried viruses included in the study was readily detectable over a long period of time. Quantitative analysis indicated that detectable concentrations of nucleic acid post-freeze drying were similarly maintained. Storage temperature was an important factor in the stability of HCV, but other viruses were unaffected by storage at different temperatures.

CONCLUSIONS

In summary, the molecular detection of nucleic acid (DNA or RNA) in freeze-dried specimens of HSV1, HSV2, HBV, HCV and HIV is possible even after prolonged storage, in some cases at a range of temperatures. Freeze drying allows large-scale production of viral specimens of high quality for EQA, which are stable in varying storage and shipment conditions. Furthermore, detection of each virus was possible with a range of commonly used molecular diagnostic methods.

Serum hepatitis B DNA: stability in relation to multiple freeze-thaw procedures

Quantitation of hepatitis B virus (HBV) DNA is often performed in specimens that have been frozen and thawed more than once. It is important to establish whether viral load measurements are affected by repeated freeze-thaw cycles. The effect of multiple freeze-thaw cycles on HBV DNA quantitation was carried out by testing serum specimens subjected to 1 (baseline) to 10 cycles with the appropriate Digene Hybrid Capture System. Five HBV DNA-positive samples were selected at random from sera with concentrations ranging from 7 pg/ml to 3529 pg/ml and they were frozen and thawed up to 10 cycles and then tested for changes in HBV DNA levels. Negative control and positive standards were tested in triplicate; and all specimens were tested in duplicate. The stability of HBV DNA in serum was evaluated by scattergram analysis by determining the number of samples showing a > or =20% change in HBV DNA levels after freeze-thaw cycles. With the exception of one sample (7 pg/ml) 10 cycles of freezing and thawing did not change significantly the HBV DNA quantity in any of the samples tested. The results showed that the quantity of HBV DNA in four of five serum specimens subjected up to 10 freeze-thaw cycles was stable.

The effect of storage at different temperatures on the stability of Hepatitis C virus RNA in plasma samples

One important issue related to Hepatitis C virus (HCV) RNA nucleic acid amplification testing (NAT) is the storage conditions of plasma samples in order to obtain reliable results. Many authors have reported that the storage conditions could affect the RNA stability and, hence, HCV RNA detection. We have studied HCV RNA stability in plasma samples after storage at different temperatures (-70, -20, 5 and 25 degrees C). Samples containing different HCV titres were stored and analysed by qualitative or quantitative NAT techniques at defined time points. At -20 degrees C, samples containing high HCV RNA titres were followed-up during approximately 2.6-2.7 years, samples with intermediate concentrations during approximately 1 year and samples with 100 International Units/millilitre (IU/ml) during 2.5 years. Independently of the HCV RNA concentration, the results show absence of decay in HCV RNA detectability. Samples stored at 25 degrees C maintain their HCV RNA titre during 14 days and samples at 5 degrees C were stable for at least 3 months.

Stable hepatitis C virus RNA detection by RT-PCR during four days storage

BACKGROUND

Suboptimal specimen processing and storage conditions of samples which contain hepatitis C virus (HCV) RNA may result in a decline of HCV RNA concentration or false-negative results in the detection of HCV RNA in serum. We evaluated the stability of HCV RNA in serum and clotted blood samples stored at room temperature or at 4 degrees C for 4 days with the aim of optimizing the standard procedures of processing and storage of samples.

METHODS

Blood from five HCV RNA positive patients was collected in tubes with and without separator gel, centrifuged 1 or 6 hours after collection. Samples were then left 6, 24, 48, 72 or 96 h at room temperature (21.5 - 25.4 degrees C) or at 4 degrees C before determining their HCV RNA level using the COBAS AMPLICOR HCV MONITOR Test, vs 2.0 (Roche Diagnostic Systems).

RESULTS

The logarithm of the HCV RNA level measurements remained within a 0.3 value of the means for 4 days at both temperatures (room temperature or 4 degrees C).

CONCLUSIONS

We conclude that blood samples may be collected and aliquoted within 6 h of collection and can be stored at 4 degrees C for 72 hours as proposed by the manufacturer without significant differences in measured HCV RNA level. Our results indicate that lapses in this scheme may still yield reliable results.

Quantitative stability of DNA after extended storage of clinical specimens as determined by real-time PCR

Viral DNA stored for extended periods can be amplified by PCR. However, it is unknown whether stored specimens give accurate quantitative results by newer real-time PCR techniques. We therefore compared herpes simplex virus DNA levels in specimens before and after 16 months of storage. The levels of viral DNA remained stable whether the DNA was stored as purified DNA or unextracted DNA in a whole specimen.

Seroprevalence of hepatitis C markers among intravenous drug users in western European countries: a systematic review

Currently, the most important risk factor for hepatitis C virus (HCV) infection in Europe is intravenous drug use. To establish a better insight into the epidemiology of hepatitis C among intravenous drug users (IVDUs) in western European countries a systematic review on the prevalence of hepatitis C markers and their determinants was performed. Reports were identified by searches on Medline and on the internet and by screening reference lists of selected papers. The prevalence rates of anti-HCV in western European IVDUs reported in the 66 studies selected for analysis, ranged between 37 and 98%. No relation was found between prevalence rates and mean age, mean duration of intravenous drug use, geographical area, setting of the study, method of recruitment or the year(s) of collection of samples. Eleven studies concerning the prevalence of HCV-RNA in hepatitis C-infected IVDUs were selected for analysis. Prevalence rates ranged from 26 to 86%. Based on five studies, a statistically significant positive linear relation was found between the mean age of study population and the prevalence of HCV-RNA. Our analysis revealed considerable variation in prevalence rates of hepatitis C markers among IVDUs in western Europe. We found no conclusive explanation for this variability. Further research investigating the dynamics of the hepatitis C epidemic in IVDUs is necessary.

Molecular testing in the diagnosis and management of hepatitis C virus infection

OBJECTIVES

To review hepatitis C virus (HCV), describe the types of molecular-based tests available for the diagnosis and management of HCV infection, and discuss the appropriate utilization of these tests.

DATA SOURCES

Current information is presented from the published literature, as well as new information where available.

STUDY SELECTION

A major cause of posttransfusion and community-acquired non-A, non-B hepatitis worldwide is HCV. Approximately 4 million people in the United States are infected with HCV, resulting in 8000 to 10,000 deaths annually. Because HCV is not readily cultured, in vitro molecular-based tests have been developed for use in the diagnosis and treatment of HCV-infected patients. Molecular tests include qualitative and quantitative nucleic acid amplification tests, branched DNA tests, and HCV genotyping assays. Qualitative HCV nucleic acid amplification tests are used routinely in association with serologic tests to help make a diagnosis of infection with HCV. Quantitative HCV testing and genotyping methods have been found to be valuable tools in the treatment of infected patients. A patient's pretreatment HCV viral load and the rate of virus decline during therapy have been shown to correlate with the likelihood of long-term response to antiviral therapy. Information pertaining to the genotype of HCV infecting patients has been shown to be helpful in making recommendations regarding treatment. Certain genotypes of HCV are much more responsive to therapy, allowing a shorter course of treatment.

CONCLUSIONS

Molecular tests are valuable tools for use in the diagnosis and treatment of patients infected with HCV.

The emerging nosocomial pathogens Cryptosporidium, Escherichia coli O157:H7, Helicobacter pylori, and hepatitis C: epidemiology, environmental survival, efficacy of disinfection, and control measures

New and emerging infectious diseases pose a threat to public health and may be responsible for nosocomial outbreaks. Cryptosporidium parvum and Escherichia coli are gastrointestinal pathogens that have caused nosocomial infections via person-to-person transmission, environmental contamination, or contaminated water or food. Helicobacter pylori has been transmitted via inadequately disinfected endoscopes. Finally, hepatitis C may be acquired by healthcare personnel by percutaneous or mucous membrane exposure to blood or between patients by use of contaminated blood products or via environmental contamination. Rigorous adherence to Standard Precautions, Contact Precautions for patients with infectious diarrhea, disinfection of environmental surfaces, and appropriate disinfection of endoscopes are adequate to prevent nosocomial acquisition of these pathogens.

Effects of storage and type of blood collection tubes on hepatitis C virus level in whole blood samples

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.

Single-tube single-enzyme reverse transcriptase PCR assay for detection of bovine viral diarrhea virus in pooled bovine serum

A reverse transcriptase PCR (RT-PCR) was developed for use as a diagnostic screening test for the detection of bovine viral diarrhea virus (BVDV) in pooled bovine serum samples. Individual serum samples from 60 dairy cattle herds located in Pennsylvania were evaluated by the microplate virus isolation method, and pooled sera were analyzed by RT-PCR. RT-PCR was sensitive and specific and detected a single viremic serum sample in up to 100 pooled serum samples. RT-PCR analysis of pooled sera provides a rapid and cost-effective method for the screening of cattle herds for the presence of animals persistently infected with BVDV.

Diagnosis and Monitoring of Hepatic Injury. I. Performance Characteristics of Laboratory Tests

Purpose: To review information on performance characteristics for tests that are commonly used to identify acute and chronic hepatic injury.

Data Sources and Study Selection: A MEDLINE search was performed for key words related to hepatic tests, including quality specifications, aminotransferases, alkaline phosphatase, γ-glutamyltransferase, bilirubin, albumin, ammonia, and viral markers. Abstracts were reviewed, and articles discussing performance of laboratory tests were selected for review. Additional articles were selected from the references.

Guideline Preparation and Review: Drafts of the guidelines were posted on the Internet, presented at the AACC Annual Meeting in 1999, and reviewed by experts. Areas requiring further amplification or literature review were identified for further analysis. Specific recommendations were made based on analysis of published data and evaluated for strength of evidence and clinical impact. The drafts were also reviewed by the Practice Guidelines Committee of the American Association for the Study of Liver Diseases and approved by the committee and the Association’s Council.

Recommendations: Although many specific recommendations are made in the guidelines, some summary recommendations are discussed here. Alanine aminotransferase is the most important test for recognition of acute and chronic hepatic injury. Performance goals should aim for total error of <10% at the upper reference limit to meet clinical needs in monitoring patients with chronic hepatic injury. Laboratories should have age-adjusted reference limits for enzymes in children, and gender-adjusted reference limits for aminotransferases, γ-glutamyltransferase, and total bilirubin in adults. The international normalized ratio should not be the sole method for reporting results of prothrombin time in liver disease; additional research is needed to determine the reporting mechanism that best correlates with functional impairment. Harmonization is needed for alanine aminotransferase activity, and improved standardization for hepatitis C viral RNA measurements.

High rate of TTV infection in multitransfused patients with pediatric malignancy and hematological disorders

The prevalence of transfusion-transmitted virus (TTV) infection has not been known in patients suffering from pediatric malignancies and hematological disorders who receive blood transfusion and/or blood products during treatment. Blood samples were taken from 75 patients. TTV infection was identified when TTV DNA was detected in serum by a polymerase chain reaction (PCR) assay. Hepatitis C virus (HCV) and hepatitis G virus (HGV) RNA were also assayed by PCR. TTV DNA was detected in 38 of 75 patients (51%). In 4 of 38 patients, the amount of blood transfused was less than 3 units. By time since last transfusion, TTV DNA was detected in 12 of 35 patients after more than 4 years, 12 of 21 between 1 and 4 years, and 14 of 19 within 1 year. Six patients had mixed infection of TTV and HCV, and 12 patients had mixed infection of TTV and HGV. Three different kinds of virus were found simultaneously in serum from 3 patients. Eight out of 75 patients showed abnormal levels of alanine aminotransferase (ALT) (>40 IU/liter), and 3 of them had TTV DNA. All patients who had TTV DNA and elevated ALT levels also were positive for HCV RNA and HGV RNA. The prevalence of TTV infection is high in patients with pediatric malignancies and hematological disorders after episodes of blood transfusion. Transfusion is one of the most important risk factors for TTV infection regardless of the amount of blood transfused.

Risk and management of blood-borne infections in health care workers

Exposure to blood-borne pathogens poses a serious risk to health care workers (HCWs). We review the risk and management of human immunodeficiency virus (HIV), hepatitis B virus (HBV), and hepatitis C virus (HCV) infections in HCWs and also discuss current methods for preventing exposures and recommendations for postexposure prophylaxis. In the health care setting, blood-borne pathogen transmission occurs predominantly by percutaneous or mucosal exposure of workers to the blood or body fluids of infected patients. Prospective studies of HCWs have estimated that the average risk for HIV transmission after a percutaneous exposure is approximately 0.3%, the risk of HBV transmission is 6 to 30%, and the risk of HCV transmission is approximately 1.8%. To minimize the risk of blood-borne pathogen transmission from HCWs to patients, all HCWs should adhere to standard precautions, including the appropriate use of hand washing, protective barriers, and care in the use and disposal of needles and other sharp instruments. Employers should have in place a system that includes written protocols for prompt reporting, evaluation, counseling, treatment, and follow-up of occupational exposures that may place a worker at risk of blood-borne pathogen infection. A sustained commitment to the occupational health of all HCWs will ensure maximum protection for HCWs and patients and the availability of optimal medical care for all who need it.

The stability of hepatitis C virus RNA after storage at +4 degrees C

One of the major issues in nucleic acid testing is how to store blood samples to obtain reliable results. We therefore studied hepatitis C virus (HCV) RNA concentration in samples after storage at +4 degrees C or freezing and thawing. Six HCV RNA-positive, untreated subjects were studied. Blood samples were collected from these subjects in plasma preparation tubes. The HCV RNA concentration was analysed after storage at +4 degrees C for 168 h or after five freeze-thaw cycles. For HCV RNA quantification we used a qualitative and a quantitative commercial test. After 168 h of storage at +4 degrees C, the HCV RNA concentration was similar to that observed at time-point 0 (5.025 log vs 5.492 log). In one sample we observed a significant fall in HCV RNA concentration. After five freeze-thaw cycles, the HCV RNA concentration was lower than that observed at time-point 0 (4.454 log vs 5.492 log) and in four samples we observed a significant fall in HCV RNA concentration. Our data suggest that HCV RNA is stable in whole blood samples stored at +4 degrees C for 168 h. Based on our results, we conclude that the standard procedures for transport of blood samples (at room temperature for a maximum of 5 h) and storage schedules (+4 degrees C for a maximum of 48 h) can be maintained without compromising the quality of results.

Risk and management of blood-borne infections in health care workers

Exposure to blood-borne pathogens poses a serious risk to health care workers (HCWs). We review the risk and management of human immunodeficiency virus (HIV), hepatitis B virus (HBV), and hepatitis C virus (HCV) infections in HCWs and also discuss current methods for preventing exposures and recommendations for postexposure prophylaxis. In the health care setting, blood-borne pathogen transmission occurs predominantly by percutaneous or mucosal exposure of workers to the blood or body fluids of infected patients. Prospective studies of HCWs have estimated that the average risk for HIV transmission after a percutaneous exposure is approximately 0.3%, the risk of HBV transmission is 6 to 30%, and the risk of HCV transmission is approximately 1.8%. To minimize the risk of blood-borne pathogen transmission from HCWs to patients, all HCWs should adhere to standard precautions, including the appropriate use of hand washing, protective barriers, and care in the use and disposal of needles and other sharp instruments. Employers should have in place a system that includes written protocols for prompt reporting, evaluation, counseling, treatment, and follow-up of occupational exposures that may place a worker at risk of blood-borne pathogen infection. A sustained commitment to the occupational health of all HCWs will ensure maximum protection for HCWs and patients and the availability of optimal medical care for all who need it.

Comparison between three quantitative assays in patients with chronic hepatitis C and their relevance in the prediction of response to therapy

To compare three quantitative assays measuring viral load in patients with chronic hepatitis C and to determine their value in predicting response to interferon (IFN) therapy, we analysed serum from 896 patients from eight European Centres using QUANTIPLEXtrade mark bDNA, MONITOR AMPLICORtrade mark and SUPERQUANTtrade mark assays. Analyses were performed on the same sample. Viral genotype was assessed using INNO-LiPA HCV II kits. Intercentre variations were observed that were related to the handling of specimens not processed and stored within 6 h of blood sampling. Among sera with optimal handling, a stronger correlation was observed between bDNA and SUPERQUANT (0.806) than between bDNA and MONITOR (0.677) and between MONITOR and SUPERQUANT (0.632). These discrepancies were greatest with genotype 2 (bDNA/SUPERQUANT= 0.772; bDNA/MONITOR=0. 456; SUPERQUANT/MONITOR= 0.299). This correlation was influenced by viraemia level and was better at lower viral loads. The proportion of sera with undetectable viral load was 15% with bDNA, 9.7% with MONITOR and 7.7% with SUPERQUANT. For the three measurements, the best cut-offs of sustained response to IFN treatment were located at their detection threshold. Among patients with viral load below the detection level, a sustained response was observed in 35% tested with bDNA, 38% with MONITOR and 80% with SUPERQUANT. Hence a stronger correlation was observed between bDNA and SUPERQUANT than between either of these assays and MONITOR. SUPERQUANT was the most sensitive assay and this greater sensitivity was associated with a better predictive value of treatment response.

Early detection of hepatitis C allograft reinfection after orthotopic liver transplantation: a molecular and histologic study

After orthotopic liver transplantation (OLT), patients with chronic hepatitis C virus (HCV) infection show nearly universal persistence of viremia and reinfection of the liver, but identifying the point at which the liver is reinfected morphologically can be difficult. One tool that may potentially be useful to detect reinfection is reverse transcriptase-polymerase chain reaction (RT-PCR), which has proven to be highly sensitive for detecting HCV RNA in formalin-fixed paraffin-embedded liver tissue. Our purpose was to gain insight into the time frame of HCV reinfection by assaying for HCV RNA in serial posttransplant liver biopsy specimens. Our study population consisted of 14 patients who underwent liver transplantation for hepatitis C and had confirmed HCV RNA in pretransplant serum, absence of HCV RNA in donor livers, and available consecutive posttransplant liver allograft specimens. We performed RT-PCR for HCV RNA in serial posttransplant liver biopsy specimens, beginning at 1 week until at least one biopsy from each tested positive. HCV RNA was detected in liver tissue by RT-PCR in 1-week post-OLT liver samples in 6 of 14 (42.8%) patients, the earliest being 5 days post-OLT. Eventually, each of the remaining eight samples became RT-PCR positive as well; the first detections occurred in these at 3 weeks (three cases), 4 weeks (three cases), 48 weeks (one case), and 144 weeks (one case). Histologic identification of hepatitis C recurrence was relatively insensitive in relation to these molecular data. These data suggest that (1) HCV RNA reinfection is nearly universal after liver transplantation in patients with chronic hepatitis C infection, (2) molecular reinfection by HCV occurs at a variable interval post-OLT, with the majority of allograft livers reinfected as early as 1 week, and (3) morphologic features of hepatitis C are usually appreciable at the time of "molecular" recurrence.

Diagnostic tests for hepatitis C

Two categories of virological assays are in practice used for the diagnosis and management of hepatitis C virus (HCV) infection, including serological and molecular biology-based assays. Serological assays include: screening tests based on enzyme immunoassays (EIAs); supplemental "analytical" assays based on immunoblot testing; and serological assays detecting genotype-specific antibodies for the serological determination of HCV genotype, so-called "serotyping" assays. Molecular assays include: qualitative assays, detecting HCV RNA in body fluids; quantitative assays measuring HCV viral load, a parameter that estimates the level of HCV replication in the liver; and tests analyzing the sequence of HCV genomes (genotyping assays).

Low Levels of Hepatitis C Virus RNA in Serum, Plasma, and Peripheral Blood Mononuclear Cells of Injecting Drug Users During Long Antibody-Undetectable Periods Before Seroconversion

Screening of antibodies to hepatitis C virus (HCV) is widely used for monitoring the prevalence of HCV infections and to assess HCV infectivity. Among HCV-infected individuals in the general population, the interval between the detection of HCV RNA and the development of HCV antibodies is usually 5 to 6 weeks, but in rare cases, seroconversion may be prolonged up to 6 to 9 months. In this study, we tested for the presence of HCV RNA during the antibody-undetectable period of 19 drug-injecting HCV seroconverters to gain insight into the antibody-negative carrier status in this population. HCV seroconversion status was determined by testing the first and last serum samples obtained from each subject, using third-generation antibody screening and confirmation assays. Serial samples were tested for HCV-specific antibodies to establish the moment of seroconversion and HCV RNA by single reverse transcriptase-polymerase chain reaction (RT-PCR) and branched DNA assay (bDNA) in serum. Plasma and peripheral blood mononuclear cells (PBMCs) were independently collected and tested for HCV RNA. HCV RNA-positivity was confirmed by Southern blot hybridization and sequencing of serial samples. The 19 HCV seroconverters had a mean follow-up of 5 years (range, 1 to 8 years). Of the 19, 4 were human immunodeficiency virus (HIV)-infected before HCV seroconversion. HCV RNA was detected in serum before seroconversion in 12 (63.2%) of the 19 HCV seroconverters, independent of HIV status. In 7 of these 12, the antibody-undetectable period was relatively short (2 to 10 months). The other 5, who were all HIV-negative before HCV seroconversion, had intermittent low levels of HCV RNA before seroconversion for a period of more than 12 months, with a mean of 40.8 months (range, 13 to 94 months). In all 5 individuals, independent repeats of the experiments confirmed the presence of HCV RNA in serum, and in 3 of these individuals, HCV-positivity was confirmed in independently collected plasma and PBMC samples. Low levels of HCV RNA may be present during prolonged antibody-undetectable periods before seroconversion in a number of injecting drug users. Independent of HIV status, their immune system appears to be unable to respond to these low HCV RNA levels and was sometimes only activated after reinfections with distinct HCV genotypes. These results indicate that primary HCV infection may not always elicit the rapid emergence of HCV antibodies and suggests that persistent low levels of HCV RNA (regardless of the genotype) may not elicit at all or delay antibody responses for prolonged periods of time.

Low Levels of Hepatitis C Virus RNA in Serum, Plasma, and Peripheral Blood Mononuclear Cells of Injecting Drug Users During Long Antibody-Undetectable Periods Before Seroconversion

Screening of antibodies to hepatitis C virus (HCV) is widely used for monitoring the prevalence of HCV infections and to assess HCV infectivity. Among HCV-infected individuals in the general population, the interval between the detection of HCV RNA and the development of HCV antibodies is usually 5 to 6 weeks, but in rare cases, seroconversion may be prolonged up to 6 to 9 months. In this study, we tested for the presence of HCV RNA during the antibody-undetectable period of 19 drug-injecting HCV seroconverters to gain insight into the antibody-negative carrier status in this population. HCV seroconversion status was determined by testing the first and last serum samples obtained from each subject, using third-generation antibody screening and confirmation assays. Serial samples were tested for HCV-specific antibodies to establish the moment of seroconversion and HCV RNA by single reverse transcriptase-polymerase chain reaction (RT-PCR) and branched DNA assay (bDNA) in serum. Plasma and peripheral blood mononuclear cells (PBMCs) were independently collected and tested for HCV RNA. HCV RNA-positivity was confirmed by Southern blot hybridization and sequencing of serial samples. The 19 HCV seroconverters had a mean follow-up of 5 years (range, 1 to 8 years). Of the 19, 4 were human immunodeficiency virus (HIV)-infected before HCV seroconversion. HCV RNA was detected in serum before seroconversion in 12 (63.2%) of the 19 HCV seroconverters, independent of HIV status. In 7 of these 12, the antibody-undetectable period was relatively short (2 to 10 months). The other 5, who were all HIV-negative before HCV seroconversion, had intermittent low levels of HCV RNA before seroconversion for a period of more than 12 months, with a mean of 40.8 months (range, 13 to 94 months). In all 5 individuals, independent repeats of the experiments confirmed the presence of HCV RNA in serum, and in 3 of these individuals, HCV-positivity was confirmed in independently collected plasma and PBMC samples. Low levels of HCV RNA may be present during prolonged antibody-undetectable periods before seroconversion in a number of injecting drug users. Independent of HIV status, their immune system appears to be unable to respond to these low HCV RNA levels and was sometimes only activated after reinfections with distinct HCV genotypes. These results indicate that primary HCV infection may not always elicit the rapid emergence of HCV antibodies and suggests that persistent low levels of HCV RNA (regardless of the genotype) may not elicit at all or delay antibody responses for prolonged periods of time.

High rate of chronicity in HCV infection determined by antibody confirmatory assay and PCR in 4110 patients during long-term follow-up

BACKGROUND

It is still unclear how many patients with hepatitis C virus (HCV) antibodies have viremia and hence are infectious.

OBJECTIVES

To determine the chronicity of HCV infection by correlation of HCV antibodies with presence of viremia in long-term follow-up.

STUDY DESIGN

In a longitudinal study sera of 4110 patients were analyzed with second generation HCV-enzyme immunoassay (EIA) and polymerase chain reaction (PCR). Only those patients were included in this study in whom sequential serum samples over a period of 2 years were available. To avoid preanalytical and analytical failures, we used a transport solution to prevent RNA degradation and a four-antigen recombinant immunoblot assay, established in our laboratory, for confirmation of antibody reactivity.

RESULTS

Of 2815 patients with confirmed HCV antibodies 2784 (98.9%) were also positive in HCV-PCR assay. False reactive EIA results were detected in 177 (13.7%) individuals as shown by confirmatory assay and PCR. Only one patient (0.04%) spontaneously lost detectable HCV viremia and subsequently HCV-specific antibodies.

CONCLUSIONS

Our study clearly demonstrates that presence of confirmed HCV-specific antibodies correlates significantly (98.9%; P < 0.001) with HCV viremia, and that spontaneous loss of viremia is a very rare event in HCV infection. We also found that elimination of HCV infection is not sufficiently predicted by the loss of detectable viremia in PCR, but can be concluded from the disappearance of virus-specific antibodies.

The effect of saliva specimen collection, handling and storage protocols on hepatitis C virus (HCV) RNA detection by PCR

OBJECTIVES

Commercial assays can now be adapted to detect salivary anti-hepatitis C virus (HCV) antibodies, increasing the potential of saliva as a non-invasive diagnostic specimen suited to surveillance and epidemiological studies. However, current diagnostic algorithms involve confirmation of HCV infection by RT-PCR. Manipulation and storage conditions of serum can influence the stability of viral RNA. This study examined whether varying specimen collection, handling and storage protocols also affected subsequent HCV RNA detection by RT-PCR applied to saliva specimens.

METHODS

Whole unstimulated saliva, together with saliva samples collected in two commercially available devices (Salivette and Omnisal) were obtained from 50 HCV seropositive intravenous drug users. The specimens were subjected to a number of handling and storage conditions, including heat treatment and prolonged storage, then examined for HCV RNA by RT-PCR using primers derived from the 5' non-coding region (5'NCR).

RESULTS

HCV RNA was detected in saliva samples from 25 (50%) of the patients. No single collection device or handling procedure identified all the subjects with HCV RNA positive saliva though whole saliva yielded the greatest number of positive results.

CONCLUSIONS

Collection and processing of saliva specimens for RT-PCR analysis is complex. At present, detection of salivary HCV RNA by PCR is not sufficiently sensitive for use as a diagnostic tool in epidemiological studies.

Branched DNA signal amplification for direct quantitation of nucleic acid sequences in clinical specimens

In this chapter I have reviewed the development of bDNA as a method for quantitation of nucleic acid targets and the application of this technology to the study of infectious diseases and cell biology. The ability to quantify viral nucleic acids in clinical specimens has led to a better understanding of the pathogenesis of chronic viral infections such as HIV-1, HCV, and HBV. The information provided by these methods can also be important in the management of patients with these infections. The prognostic value of a single baseline HIV-1 RNA level rivals that surgical staging procedures for cancer, which are among the most powerfully predictive tests in medicine (Mellors et al., 1996). These methods have been used to assess rapidly the effects of antiviral therapy, which has both expedited the development of antiviral drugs and improved the management of patients with HIV-1 and HCV infections. bDNA has several characteristics that distinguish it from the quantitative target amplification systems, including better tolerance of target sequence variability, more direct measurement of target, simpler sample preparation, and less sample-to-sample variation. However, the first- and second-generation bDNA assays lacked sensitivity compared with the target amplifications systems. The changes incorporated into the third-generation assays have effectively increased the signal-to-noise ratio to such a high level that the analytical sensitivity of system 8 bDNA approaches that of PCR. In theory, bDNA can be made even more sensitive by increasing both the sample volume and the signal-to-noise ratio. Nonspecific hybridization can be further reduced by finding more effective blockers for the solid phase or by redesigning the amplifier molecule or the solid phase itself. The increased sensitivity may create new applications for the technology in filter and in situ hybridization assays.

Hepatitis C virus infection in dialysis: a continuing problem

Patients on chronic dialysis are at increased risk of acquiring parenterally transmitted hepatitis viruses from blood product transfusions or nosocomial transmission in hemodialysis units, and biochemical abnormalities in liver function are seen in 10-44% of patients on chronic hemodialysis. In the past, hepatitis B virus (HBV) was the major cause of parenterally transmitted viral hepatitis in dialysis patients, and the remaining cases were attributed to non-A, non-B hepatitis (NANBH). The discovery of the hepatitis C virus (HCV) has shed light on the cause and clinical course of NANBH in patients on dialysis. The current debate is focused on strategies to reduce the transmission of HCV among dialysis patients and to lessen the consequences of liver disease among patients already infected.

Hepatitis G Virus RNA and Hepatitis G Virus-E2 Antibodies in Dutch Hemophilia Patients in Relation to Transfusion History

The prevalence of hepatitis G virus (HGV)-RNA and HGV-E2 antibodies was studied in a cohort of Dutch hemophilia patients in relation to clotting products used, age, and coinfection with hepatitis C. Between 1991 and 1995, blood samples were taken from 294 patients with hemophilia A, B, or von Willebrand disease. From each patient one fresh frozen sample was tested for HGV cDNA polymerase chain reaction (PCR) and HCV cDNA PCR. Alanine aminotransferase (ALT) tests were performed on plasma samples of all patients. The presence of HGV-E2 antibodies was tested on plasma samples from a subset of 169 patients representing all age groups. Based on the origin and viral safety of the products used, three subgroups of patients were distinguished. Group A: patients who used viral noninactivated factors derived from small and large donor pools; group B: patients who used factors prepared with inadequate viral inactivation techniques derived from small and large donor pools; and group C: patients treated only with optimally viral inactivated large pool clotting factor or recombinant clotting factor concentrate. The prevalence of HGV-RNA was 18%. In group A patients the prevalence was 71%, in group B 50%, and in group C 6%. When related to age, the highest prevalence of HGV-RNA (35%) was seen in patients born between 1980 and 1989. The prevalence of HGV-E2 antibodies increased with age. Of HGV-RNA–negative patients born before 1950, 96% tested positive. HGV viremia did not affect ALT levels, neither in HCV-RNA positive nor in HCV-RNA negative patients. HGV infection is frequently seen in patients with hemophilia. In older age groups a lower rate of HGV-RNA positivity is seen coinciding with a higher rate of antienvelope antibodies.

© 1998 by The American Society of Hematology.

Hepatitis G Virus RNA and Hepatitis G Virus-E2 Antibodies in Dutch Hemophilia Patients in Relation to Transfusion History

The prevalence of hepatitis G virus (HGV)-RNA and HGV-E2 antibodies was studied in a cohort of Dutch hemophilia patients in relation to clotting products used, age, and coinfection with hepatitis C. Between 1991 and 1995, blood samples were taken from 294 patients with hemophilia A, B, or von Willebrand disease. From each patient one fresh frozen sample was tested for HGV cDNA polymerase chain reaction (PCR) and HCV cDNA PCR. Alanine aminotransferase (ALT) tests were performed on plasma samples of all patients. The presence of HGV-E2 antibodies was tested on plasma samples from a subset of 169 patients representing all age groups. Based on the origin and viral safety of the products used, three subgroups of patients were distinguished. Group A: patients who used viral noninactivated factors derived from small and large donor pools; group B: patients who used factors prepared with inadequate viral inactivation techniques derived from small and large donor pools; and group C: patients treated only with optimally viral inactivated large pool clotting factor or recombinant clotting factor concentrate. The prevalence of HGV-RNA was 18%. In group A patients the prevalence was 71%, in group B 50%, and in group C 6%. When related to age, the highest prevalence of HGV-RNA (35%) was seen in patients born between 1980 and 1989. The prevalence of HGV-E2 antibodies increased with age. Of HGV-RNA–negative patients born before 1950, 96% tested positive. HGV viremia did not affect ALT levels, neither in HCV-RNA positive nor in HCV-RNA negative patients. HGV infection is frequently seen in patients with hemophilia. In older age groups a lower rate of HGV-RNA positivity is seen coinciding with a higher rate of antienvelope antibodies.

© 1998 by The American Society of Hematology.

Stability of hepatitis C virus RNA during specimen handling and storage prior to NASBA amplification

The influence of different anticoagulants and pre-amplification storage conditions on the stability of hepatitis C virus (HCV)-RNA, as detected by the quantitative HCV NASBA assay (NASBA-QT), was studied. The HCV-RNA load remained stable for at least 15 months when serum or plasma samples (EDTA and heparin) were directly frozen at -70 degrees C in lysis buffer. At 4 degrees C, the HCV-RNA load in serum or plasma stored with lysis buffer did not decline for at least 14 days. At 30 degrees C, however, the load declined significantly after 7 days. When clotted, whole blood was stored at 4 degrees C, the HCV-RNA load was stable for 72 h. However, when EDTA-anticoagulated whole blood was stored at 4 degrees C, the HCV-RNA load declined significantly after 48 h. In paired plasma and serum samples at baseline the HCV-RNA levels were similar. Heparin did not influence the efficiency of the HCV NASBA-QT assay. Clotted blood as well as EDTA or heparin anticoagulated blood can be used for quantifying HCV-RNA using the NASBA-QT assay. Blood samples should be stored at 4 degrees C after collection and serum or plasma separated within 24 h. Preferably, after separation, samples should be frozen in lysis buffer at -70 degrees C until NASBA-QT analysis.

Universal diagnostic RT-PCR protocol for arboviruses

A selected number of PCR protocols were evaluated to determine if they could serve as a universal protocol for detecting and identifying all arboviruses. In this study, four parameters that affect the efficacy of RT-PCR (RNA extraction method, choice of reverse transcriptase, choice of DNA polymerase and thermocycling program) were evaluated in combination. The most optimal combination of those parameters employed use of silica gel membrane spin column, RAV-2 reverse transcriptase, Tth DNA polymerase, and a simple modification of a published thermocycling program. By this modified protocol, viral RNA could be amplified satisfactorily with more than 50 pairs of primers designed for diagnosis of arboviruses representing five families. The sensitivity and specificity obtained by this universal protocol were comparable to those obtained by the original protocol for each primer pair tested; and for some primers, improved sensitivity was observed. It was also found that a simple modification of a suggested protocol of a commercial RT-PCR kit could produce nearly identical results and serve as another universal protocol. With the use of a universal diagnostic reverse transcriptase-polymerase chain reaction (RT-PCR) protocol, simultaneous screening of clinical or biological specimens against a large number of RNA viruses belonging to many families can be performed more efficiently for etiologic determination in the situations complicated by the difficulty of differential diagnosis. Furthermore, such a universal protocol facilitates reducing the cost of PCR-based diagnostic operation and standardizing the qualities of PCR-based diagnosis within an institution or among collaborating institutions. A logical strategy is to conduct diagnosis in two stages by using broadly group-reactive primers in the first stage to narrow the range of possible etiologic agents and using virus-specific primers in the second stage for identification. Before such a strategy is employed, however, more group-reactive primers for a large number of arboviruses, for which no such primers currently exist, must be made available. Furthermore, the best pair or pairs of primers need to be selected for each virus for the second stage of the strategy.

Assessment of hepatitis B virus DNA stability in serum by the Chiron Quantiplex branched-DNA assay

Quantification of hepatitis B virus (HBV) DNA in serum is used to establish eligibility for treatment and to monitor therapeutic response. With the trend toward centralized testing, defining the conditions that preserve sample integrity is of paramount importance. We therefore evaluated the stability of HBV DNA in 26 previously frozen (PF) and 5 fresh, never previously frozen serum specimens. PF specimens, covering a 3-log10 HBV DNA dynamic range, were thawed and stored at -70, 4, 23, 37, and 45 degrees C (+/-1.5 degrees C) for 0, 24, 72, and 120 h (+/-2 h) and were refrozen at -70 degrees C prior to testing. Five fresh specimens were split into two groups. Both group FG1 and group FG2 specimens were handled as described above; however, group FG1 specimens were subsequently maintained at 4 degrees C and were never frozen prior to testing. Linear regression analysis of PF specimens demonstrated no significant HBV DNA degradation at < or =4 degrees C over 5 days; however, HBV DNA levels decreased by 1.8, 3.4, and 20% per day at 23, 37, and 45 degrees C, respectively. Three independent statistical methods confirmed that the probability of specimen failure, defined as a loss of 20% or more of HBV DNA and/or coagulation of serum, was lowest at < or =4 degrees C and increased with temperature. Because only 10 to 20% of individual patient specimens demonstrated losses of HBV DNA of > or =20% at 23 or 37 degrees C, sufficient numbers of serum specimens must be evaluated to determine overall statistical trends. In conclusion, HBV DNA integrity in separated serum specimens is preserved for at least 5 days when the specimens are stored at -70 or 4 degrees C.

Serologic responses to hepatitis C virus in solid organ transplant recipients

BACKGROUND

Hepatitis C (HCV) infection is known to have been transmitted by both blood transfusion and donor organs. We sought to determine the historical incidence of donor- and transfusion-acquired HCV infection in kidney transplant (RTx) and heart transplant (HTx) recipients at our center and to study the kinetics of seroconversion to HCV.

METHODS

A bank of sera collected from organ donors (388 RTx and 88 HTx) who received allografts between January 1984 and April 1992 was screened for anti-HCV using a third generation enzyme immunoassay. Recipient sera collected before transplant (preTx), at 1 year after transplant, and at last follow-up were tested. Fresh follow-up sera on all surviving anti-HCV-positive (+) RTx and HTx, all anti-HCV-negative (-) HTx, and a subset of 85 anti-HCV- RTx were assayed for HCV RNA using an reverse transcriptase-polymerase chain reaction assay.

RESULTS

Twenty-four of 388 RTx (6.2%) and 2 of 88 HTx (2.3%) were anti-HCV+ preTx. Eight of 218 (3.7%) organ donors were anti-HCV+. Six of the seven (85.7%) anti-HCV+ donors with adequate recipient follow-up transmitted HCV infection to one or more recipients. Nineteen of 313 RTx (6.1%) and 8 of 72 HTx (11.1%) with follow-up > or =1 year seroconverted to anti-HCV. One of 85 (1.2%) anti-HCV- RTx and 3 of 44 (6.8%) anti-HCV-HTx were HCV RNA+ when tested at last follow-up. Five cases of de novo HCV infection occurred after the introduction of first generation anti-HCV screening of donors. Persistent viremia (HCV RNA+) at last follow-up was observed in 70.6% (12/17) RTx anti-HCV+ preTx. Fourteen of 15 (93.3%) RTx and 9 of 9 (100%) HTx with de novo HCV infection had persistent viremia. Seroconversion was more delayed in HTx than RTx (P=0.0572, log-rank Mantel-Cox statistic) although both groups demonstrated an impaired humoral response to HCV when compared with the immunocompetent host.

CONCLUSIONS

Organ donor- and transfusion-acquired HCV infection was common in RTx and HTx transplanted before the introduction of second generation anti-HCV screening in 1992. Serologic responses to HCV are often delayed and sometimes absent in these patients. Assays for HCV RNA should be considered as a screening test for the detection of HCV infection in this population. Serologic responses to HCV were more impaired in HTx compared with RTx, which may reflect the more intensive immunosuppressive regimens given to HTx at our center.

Stability of HIV-1 RNA in blood during specimen handling and storage prior to amplification by NASBA-QT

The influence of different storage temperatures and anticoagulation conditions on the HIV-1 RNA load as measured by NASBA-QT was examined. Blood specimens from 14 HIV-1 infected individuals were processed within 2 h after collection. The HIV-1 RNA load remained stable for at least 6 months when samples were frozen directly at -70 degrees C in lysis buffer. This lysis buffer fully inactivated the virus. When whole EDTA blood was stored, the HIV-1 RNA load was stable for 72 h at 25 degrees C, but it declined within 24 h at 4 degrees C. The HIV-1 RNA load in whole heparinized blood declined significantly after 24 h at both 4 and 25 degrees C. It was slightly lower (average of 0.18 log ml-1) than in whole EDTA blood. At 4 degrees C, the HIV-RNA load in serum and EDTA-plasma stored with lysis buffer did not decline up to 14 days. At + 30 degrees C, however, the load declined significantly after 2 days. Of clinical significance, the mean load in EDTA plasma was 0.5 log ml-1 higher than in serum. This difference was patient dependent (range 0.1-0.7 log ml-1). We thus recommend, for quantifying HIV-1 RNA by NASBA, to use preferably EDTA blood which is kept at room temperature until plasma separation. When using heparinized blood, the plasma should be stored frozen within 8 h.

Performance of three generations of anti-hepatitis C virus enzyme-linked immunosorbent assays in donors and patients

BACKGROUND

Prevention of posttransfusion non-A,non-B hepatitis in recipients of blood components improved considerably with the introduction of the second-generation of hepatitis C virus (HCV) antibody tests. In 1993, third-generation HCV antibody assays were introduced in Europe.

STUDY DESIGN AND METHODS

The performance of three generations of anti-HCV enzyme-linked immunosorbent assay (ELISA) (ELISA-1, -2, -3) was compared in routine blood donor screening (99,394 donations were tested with ELISA-1, 167,999 donations with ELISA-2, and 262,090 donations with ELISA-3) and in serial samples from nine patients with documented acute posttransfusion HCV infection.

RESULTS

Eight (0.01%) repeat donors, previously negative in ELISA-1, were found positive in ELISA-2 and were confirmed as positive in second-generation recombinant immunoblot assay and/or cDNA polymerase chain reaction. In the donor population, no difference in the sensitivity of ELISA-2 and -3 was observed. The specificity of the three generations of ELISAs was comparable (99.8, 99.7, and 99.7%). In seroconversion samples, ELISA-2 and -3 detected HCV antibodies at the same time in seven patients, but in two patients, ELISA-3 found HCV antibodies, respectively, 63 and 77 days earlier than ELISA-2 did. In the seroconversion samples, ELISA-2 and -3 were significantly more sensitive than second- and third-generation recombinant immunoblot assays.

CONCLUSION

ELISA-3 did not detect more HCV-infected individuals in a donor population that previously tested negative in ELISA-2, but it did detect HCV antibodies earlier in some patients with acute HCV infection. ELISA-2 and -3 were significantly more sensitive than second- and third-generation recombinant immunoblot assays.

Quantitative assessment of hepatitis C virus RNA by polymerase chain reaction and a digoxigenin detection system: comparison with branched DNA assay

A method for quantifying hepatitis C virus (HCV) RNA in serum using reverse transcription-polymerase chain reaction (RT-PCR) followed by slot-blot hybridization with a specific, digoxigenin-labeled probe was developed. Using RNA synthesized from cloned HCV cDNA as a standard, serum concentration of HCV RNA above 10 copies/ml can be quantitatively determined. To compare this method with branched DNA (bDNA) assay, 45 serum samples from 26 patients with newly acquired acute hepatitis C (n = 16) or hepatitis C with acute exacerbation (n = 10) were submitted to both assays. HCV RNA in 30 (67%), 12 (27%) and three (6.7%) samples can be quantitatively determined by both, either and none of the two assays, respectively. Using a standardized qualitative HCV RNA detection test (Amplicor HCV test) as a reference, 1 and 0 false positive results were found by bDNA and this assay, respectively. This quantitative assay using RT-PCR and a digoxigenin detection system was comparable to bDNA assay. Since a false positive result was rarely found, this technique can be used as a first line test to screen a large number of samples rapidly and economically.