HCV RNA levels in hepatocellular carcinomas and adjacent non-tumorous livers

Fingerprint Analysis and Multi-Component Determination of Ribonucleic Acid for Injection II Recipe by HPLC-DAD and LC-ESI-MS Methods

Using high-performance liquid chromatography (HPLC), a quantitative method was developed to control the quality of ribonucleic acid for injection II (RA-II), which is used as an anti-cancer drug clinically in China. Using nuclease enzyme and under optimal hydrolysis conditions, the unstable RNA was hydrolyzed into stable nucleosides and nucleotides, which were easily detected by HPLC with diode array detection. Furthermore, by analyzing HPLC chromatograms of 10 batches of samples, six common peaks, namely, cytosine nucleotide, uracil nucleotide, adenine nucleotide, guanine nucleotide, guanosine and adenine, were identified by a HLPC coupled with electrospray ionization mass spectrometry. The similarity, the relative retention time and the relative peak area of each common peak, relative to the reference peak, were calculated to obtain the HPLC fingerprints, and their values were within the scope of the provisions. More importantly, all six components were simultaneously determined. Overall, the developed method in this investigation proved to be a useful tool for monitoring the quality of RA-II in terms of their batch variations and the raw material sources.

Hepatitis C Virus-Associated Cancers

Most hepatitis C virus (HCV) infection results in persistent infection. Significant portion of chronic HCV-infected patients develop hepatocellular carcinoma (HCC). Chronic hepatitis C is also associated with extrahepatic manifestations, including cryoglobulinemia, lymphoma, insulin resistance, type 2 diabetes, and neurological disorders. The molecular mechanisms of how HCV infection causes liver cancer are largely unknown. HCV replication or viral proteins may perturb cellular hemostasis and induce the generation of reactive oxygen species (ROS); viral components or viral replication products act as agonist to trigger innate immune response and cause chronic inflammation. Within the liver, non-hepatocytes such as hepatic stellate cell (HSC) are activated upon HCV infection to provide the major source of extracellular proteins and play important roles in fibrogenesis. With the great achievements of HCV treatment, especially the direct-acting antivirals (DAAs) against HCV, HCV eradication is possible. However, until now there are only very limited data on the effect of DAA-based anti-HCV treatment on HCC patients.

Infection with hepatitis C virus depends on TACSTD2, a regulator of claudin-1 and occludin highly downregulated in hepatocellular carcinoma

Entry of hepatitis C virus (HCV) into hepatocytes is a complex process that involves numerous cellular factors, including the scavenger receptor class B type 1 (SR-B1), the tetraspanin CD81, and the tight junction (TJ) proteins claudin-1 (CLDN1) and occludin (OCLN). Despite expression of all known HCV-entry factors, in vitro models based on hepatoma cell lines do not fully reproduce the in vivo susceptibility of liver cells to primary HCV isolates, implying the existence of additional host factors which are critical for HCV entry and/or replication. Likewise, HCV replication is severely impaired within hepatocellular carcinoma (HCC) tissue in vivo, but the mechanisms responsible for this restriction are presently unknown. Here, we identify tumor-associated calcium signal transducer 2 (TACSTD2), one of the most downregulated genes in primary HCC tissue, as a host factor that interacts with CLDN1 and OCLN and regulates their cellular localization. TACSTD2 gene silencing disrupts the typical linear distribution of CLDN1 and OCLN along the cellular membrane in both hepatoma cells and primary human hepatocytes, recapitulating the pattern observed in vivo in primary HCC tissue. Mechanistic studies suggest that TACSTD2 is involved in the phosphorylation of CLDN1 and OCLN, which is required for their proper cellular localization. Silencing of TACSTD2 dramatically inhibits HCV infection with a pan-genotype effect that occurs at the level of viral entry. Our study identifies TACSTD2 as a novel regulator of two major HCV-entry factors, CLDN1 and OCLN, which is strongly downregulated in malignant hepatocytes. These results provide new insights into the complex process of HCV entry into hepatocytes and may assist in the development of more efficient cellular systems for HCV propagation in vitro.

Diminished viral replication and compartmentalization of hepatitis C virus in hepatocellular carcinoma tissue

Analysis of hepatitis C virus (HCV) replication and quasispecies distribution within the tumor of patients with HCV-associated hepatocellular carcinoma (HCC) can provide insight into the role of HCV in hepatocarcinogenesis and, conversely, the effect of HCC on the HCV lifecycle. In a comprehensive study of serum and multiple liver specimens from patients with HCC who underwent liver transplantation, we found a sharp and significant decrease in HCV RNA in the tumor compared with surrounding nontumorous tissues, but found no differences in multiple areas of control non-HCC cirrhotic livers. Diminished HCV replication was not associated with changes in miR-122 expression. HCV genetic diversity was significantly higher in livers containing HCC compared with control non-HCC cirrhotic livers. Tracking of individual variants demonstrated changes in the viral population between tumorous and nontumorous areas, the extent of which correlated with the decline in HCV RNA, suggesting HCV compartmentalization within the tumor. In contrast, compartmentalization was not observed between nontumorous areas and serum, or in controls between different areas of the cirrhotic liver or between liver and serum. Our findings indicate that HCV replication within the tumor is restricted and compartmentalized, suggesting segregation of specific viral variants in malignant hepatocytes.

Impaired expression of type I and type II interferon receptors in HCV-associated chronic liver disease and liver cirrhosis

PURPOSE

Chronic Hepatitis C Virus (HCV)-infected patients with liver cirrhosis (LC) respond poorly to interferon-alpha (IFN-α) and ribavirin (RBV) combination therapy, but the reason for this is unclear. We previously reported that HCV-infection induces endoplasmic reticulum (ER) stress and autophagy response that selectively down regulates the type I IFN-α receptor-1 (IFNAR1) and RBV transporters (CNT1 and ENT1), leading to IFN-α/RBV resistance. The goal of this study is to verify whether an increase in ER stress and autophagy response is also associated with the reduced expression of IFNAR1 and RBV transporters in chronic HCV-infected patients.

METHODS

Primary human hepatocytes (PHH) were infected with cell culture grown HCV particles (JFH-ΔV3-Rluc). HCV replication was confirmed by the detection of viral RNA by RT-qPCR and HCV-core protein by Western blotting. The ER stress and autophagy response and expression of IFN receptors and RBV transporters in HCV infected PHH and liver tissues derived from patients were measured by Western blotting.

RESULT

HCV infection of PHH showed impaired expression of IFNAR1, IFNγR1 (Type II IFN receptor) and RBV transporters but not IL10Rβ (Type III IFN-λ receptor). ER stress markers (BiP, IRE1α and peIF2α) and autophagy response (LC3II, Beclin 1 and ATG5) were induced in HCV infected chronic liver disease (CLD) and LC patients. Liver biopsies (CLD) show a 50% reduced expression of IFNAR1 and RBV transporters. Furthermore, the expression of IFNAR1 and RBV transporters was impaired in almost all LC patients.

CONCLUSION

HCV infection induces ER stress and autophagy response in infected PHH and chronically infected liver tissues. The expression of IFNAR1, IFNγR1 and RBV transporters were significantly impaired in CLD and cirrhotic livers. Our study provides a potential explanation for the reduced response rate of IFN-α and RBV combination therapy in HCV infected patients with liver cirrhosis.

Comparative analysis of proteome and transcriptome in human hepatocellular carcinoma using 2D-DIGE and SAGE

Proteome analysis of human hepatocellular carcinoma was conducted using two-dimensional difference gel electrophoresis, and the protein expression profiles were compared to the mRNA expression profiles made from serial analysis of gene expression (SAGE) in identical samples from a single patient. Image-to-image analysis of protein abundances together with protein identification by peptide mass fingerprinting yielded the protein expression profiles. A total of 188 proteins were identified, and the expression profiles of 164 proteins which had the corresponding SAGE data were compared to the mRNA expression profiles. Among them, 40 proteins showed significant differences in the mRNA expression levels between non HCC and HCC. We compared expression changes of proteins with those of mRNAs. We found that the expression tendency of 24 proteins were similar to that of mRNA, whereas 16 proteins showed different or opposite tendency to the mRNA expression.

Distinct hepatitis C virus core and F protein quasispecies in tumoral and nontumoral hepatocytes isolated via microdissection

Hepatitis C virus (HCV) genetic variability may be involved in liver carcinogenesis. We investigated HCV core and corresponding putative F protein genetic variability in hepatocellular carcinoma (HCC) and cirrhotic nodules. Hepatocyte clusters from 7 patients with HCC and HCV1b-related cirrhosis were isolated via microdissection of HCC tissues and 2 nontumoral cirrhotic nodules. The HCV core complementary DNA was cloned and sequenced from each liver compartment and from the serum of 2 patients. Nucleotide diversity and synonymous and nonsynonymous substitutions were analyzed within and between compartments via phylogenetic analysis and Mantel's test. Liver HCV RNA accumulation was lower in HCC. Increased quasispecies diversity and complexity was observed with HCC in 6 of 7 patients. Mantel's test demonstrated marked compartmentalization of quasispecies between HCC and cirrhotic nodules in all 7 patients and also between the 2 nontumoral nodules in 5 of them. Synonymous-nonsynonymous substitution analysis indicated low selection against tumoral core quasispecies in all patients and a more selective pressure against F protein quasispecies in all compartments. In the 2 subjects analyzed, HCC and nontumoral hepatocyte quasispecies were only minor or undetected in serum.

CONCLUSION

In tumoral hepatocytes, low-replicating hepatitis C quasispecies are compartmentalized and more diversified and are subjected to low selective pressure. Our study supports the importance of core genetic variability in hepatocellular carcinogenesis.

Hepatic steatosis is associated with increased frequency of hepatocellular carcinoma in patients with hepatitis C-related cirrhosis

BACKGROUND

Chronic hepatitis C can result in fatty changes in the liver. Previous studies have suggested that hepatic steatosis is a risk factor for hepatocellular carcinoma in patients with hepatitis C virus (HCV) infection. The authors sought to determine whether hepatic steatosis is associated with hepatocellular carcinoma (HCC) in a cohort of patients with hepatitis C-related cirrhosis.

METHODS

The authors retrospectively identified 94 consecutive patients with hepatitis C cirrhosis who underwent liver transplantation from 1992 to 2005 and had pathology available for review. Of these, 32 had evidence of HCC, and 62 had no HCC on explant histology. All explant specimens were graded again for steatosis by a single, blinded pathologist. Steatosis, age, sex, body mass index, HCV RNA, HCV genotype, Model for End-Stage Liver Disease (MELD) score, chronic alcohol use, and diabetes were examined in univariate and multivariate analyses for association with HCC.

RESULTS

In total, 69% of patients in the HCC group and 50% of patients in the control group had evidence of steatosis (1+) on histology. Odds ratios for the development of HCC for each grade of steatosis compared with grade 0 were as follows: grade 1 (1.61 [0.6-4.3]), grade 2 (3.68 [1.1-12.8]), and grade 3 or 4 (8.02 [0.6-108.3]) (P = .03 for the trend). In univariate analysis, there was a significant association between increasing steatosis grade (P = .03), older age (56 years vs 49 years; P < .02), higher aspartate aminotransferase (122.5 U/L vs 91.5 U/L; P = .005), higher alanine aminotransferase (95.8 U/L vs 57.2 U/L; P = .002), higher alpha-fetoprotein (113.5 ng/mL vs 17.8 ng/mL; P < .001), lower median HCV RNA (239,000 IU/mL vs 496,500 IU/mL; P = .02), higher biologic MELD score (21.8 vs 20.3; P = .03), and risk of HCC. In multivariate analysis, age (P = .02), AFP (P = .007), and steatosis (P = .045) were significantly associated with HCC.

CONCLUSIONS

In patients with HCV-related cirrhosis, the presence of hepatic steatosis is independently associated with the development of hepatocellular carcinoma. These findings suggest that steatosis poses an additional risk for HCC and that increased vigilance should be practiced in surveillance of persons with both HCV and steatosis.

Downregulation of human CD46 by adenovirus serotype 35 vectors

Human CD46 (membrane cofactor protein), which serves as a receptor for a variety of pathogens, including strains of measles virus, human herpesvirus type 6 and Neisseria, is rapidly downregulated from the cell surface following infection by these pathogens. Here, we report that replication-incompetent adenovirus (Ad) serotype 35 (Ad35) vectors, which belong to subgroup B and recognize human CD46 as a receptor, downregulate CD46 following infection. A decline in the surface expression of CD46 in human peripheral blood mononuclear cells was detectable 6 h after infection, and reached maximum (72%) 12 h after infection. Ad35 vector-induced downregulation of surface CD46 levels gradually recovered after the removal of Ad35 vectors, however, complete recovery of CD46 expression was not observed even at 96 h after removal. The surface expression of CD46 was also reduced after incubation with fiber-substituted Ad serotype 5 (Ad5) vectors bearing Ad35 fiber proteins, ultraviolet-irradiated Ad35, vectors and recombinant Ad35 fiber knob proteins; in contrast, conventional Ad5 vectors did not induce surface CD46 downregulation, suggesting that the fiber knob protein of Ad35 plays a crucial role in the downregulation of surface CD46 density. These results have important implications for gene therapy using CD46-utilizing Ad vectors and for the pathogenesis of Ads that interact with CD46.

Role of interleukin-18 and its receptor in hepatocellular carcinoma associated with hepatitis C virus infection

Interleukin (IL)-18 is a proinflammatory cytokine that is up-regulated in patients with hepatitis C virus (HCV) infection, which is the most common underlying disease in hepatocellular carcinoma (HCC). The purpose of our study was to investigate the role of IL-18 in HCC associated with HCV infection. Sixty-five patients with HCC and HCV infections who received curative surgical resections were examined in our study. The expression of the IL-18 receptor was investigated in HCC tissues obtained from these patients and in 2 HCC cell lines. Nuclear factor (NF)-kappaB activity and the expression of Bcl-xL and xIAP mRNA were tested in the cell lines using recombinant human (rh) IL-18. The IL-18 receptor was expressed in both the HCC tissues and the cell lines. NF-kappaB activation and the expression of Bcl-xL and xIAP mRNA were increased by rhIL-18. Moreover, rhIL-18 suppressed the apoptosis of HCC cells which was induced by etoposide in vitro. The overall survival rate (55.4%) was significantly worse in the IL-18 receptor-positive patients than in the IL-18 receptor-negative patients (p = 0.015). In a Cox multivariate analysis, the expression of the IL-18 receptor was found to be a significant predictor of a poor outcome in HCC patients. The expression of the IL-18 receptor and an antiapoptotic mechanism involving NF-kappaB activation in HCC cells may be implicated in a poor patient outcome.

Muscarinic receptor subtypes in human bladder detrusor and mucosa, studied by radioligand binding and quantitative competitive RT-PCR: changes in ageing

1. We investigated muscarinic receptors in the detrusor and mucosa of the human bladder body. Radioligand-binding studies with [(3)H]QNB were conducted using specimens collected from patients (36-77 years) with normal bladder function, undergoing surgery. For RT-PCR, biopsies of normal bladder were obtained from patients (30-88 years) undergoing check cystoscopy. 2. Binding of [(3)H]QNB in detrusor (n=20) was of high affinity (K(D) 77.1 (55.2-99.0) pM) and capacity (B(max) 181+/-7 fmol mg protein(-1)). Similar values were obtained in mucosa (n=6) (K(D) 100.5 (41.2-159.9) pM; B(max) 145+/-9 fmol mg protein(-1)). 3. Competition-binding experiments in detrusor membranes with muscarinic receptor antagonists including trospium, darifenacin, 4-DAMP, methoctramine, AQ-RA 741, AF-DX 116 and pirenzepine indicated a receptor population of 71% M(2), 22% M(3) and 7% M(1). In the mucosa, 75% of sites were M(2) receptors, with 25% M(3)/M(5). 4. Using RT-PCR, expression of M(1), M(2), M(3) and M(5) mRNA was demonstrated in both detrusor and mucosa. 5. The presence of a high density of mainly M(2) muscarinic receptors in the mucosa appears to be a novel finding and raises the question of their physiological significance and the source of their endogenous ligand. 6. There was a negative correlation of receptor number (B(max)) with age in detrusor muscle from male patients (P=0.02). Quantitative competitive RT-PCR demonstrated a selective age-related decrease in mRNA for muscarinic M(3) but not M(2) receptors, in both male (P<0.0001) and female (P=0.019) detrusor. These findings correspond with reports of decreased detrusor contractility with ageing.

Inhibition of hepatitis C virus nonstructural protein, helicase activity, and viral replication by a recombinant human antibody clone

Hepatitis C virus (HCV) nonstructural protein 3 (NS3), with its protease, helicase, and NTPase enzymatic activities, plays a crucial role in viral replication, and therefore represents an ideal target for the development of anti-viral agents. We have developed a recombinant human antibody (Fab) that reacts with the helicase domain of HCV NS3. The affinity-purified Fab antibody completely inhibited the helicase activity of HCV NS3 at equimolar concentration. To evaluate the effect of the Fab on HCV replication, the clone encoding the Fab gene was put into an expression vector, which converts Fab into a complete IgG1 antibody. Using a DNA-based transfection model, we demonstrated that intracellular expression of this antibody resulted in significant reduction of HCV-negative strand RNA synthesis. Intracellular expression of this antibody into either a stable cell line replicating subgenomic RNA, or a transient full-length HCV replication model, reduced both HCV RNA and viral protein expression. These results support the use of recombinant antibody fragments to inhibit NS3 enzyme as a novel, feasible, and effective approach for inhibiting HCV replication.

Interferon alpha-2b inhibits negative-strand RNA and protein expression from full-length HCV1a infectious clone

We have established a T7-based model system for hepatitis C virus (HCV) 1a strain, which involves the use of a replication-defective adenovirus that carries the gene for T7 RNA polymerase and a transcription plasmid containing full-length HCV cDNA clone. To facilitate high-level expression of HCV, sub-confluent Huh7 cells were first infected with adenovirus containing the gene for the T7 RNA polymerase and then transfected with the transcription plasmid. As a negative control, part of NS5B gene of this clone was deleted which abolishes the HCV RNA-dependent RNA polymerase and prevents replication of viral RNA. This model produces high levels of structural (core, E1, E2) and nonstructural proteins (NS5), which were detected by Western blot analysis and immunofluorescence assay. Negative-strand HCV RNA was detected only in the wild-type clone in the presence of actinomycin D, and no RNA was detected with the NS5B deleted mutant control. As a practical validation of this model, we showed that IFN alpha-2b selectively inhibits negative-strand RNA synthesis by blocking at the level of protein translation. The inhibitory effect of IFN alpha-2b is not due reduction of transcription by T7 polymerase or due to intracellular degradation of HCV RNA. This in vitro model provides an efficient and reliable means of assaying negative-strand RNA, protein processing, and testing the antiviral properties of interferon.

Development and evaluation of a quantitative competitive reverse transcription polymerase chain reaction (RT-PCR) for hepatitis C virus RNA in serum using transcribed thio-RNA as internal control

A method for quantitation of hepatitis C virus (HCV) RNA was developed based on competitive reverse transcription polymerase chain reaction (RT-PCR) using in vitro transcribed mutated thio-RNA as a competitor template. The thio-RNA is more resistant to RNAse and is stable over a year. This assay was compared with the commercially available Roche Amplicor HCV Monitor assay V 2.0 and real time PCR using SYBR green 1 dye method. A total of 18 pre-therapy serum samples from chronic hepatitis C cases were tested in parallel by the three assays. All samples could be quantitated using the in-house competitive RT-PCR and real time PCR and there was a significant correlation in the virus titer (P<0.05). However, 8 (44%) samples could not be quantified by Amplicor HCV Monitor assay, which has a lower detection range (10(2) to 10(5.5) copies/ml). The in-house method of competitive RT-PCR showed a detection range of 10(3) to 10(10) copies/ml. In the patients the mean viral titer was found to be (9.66+/-9.3)x10(6) copies/ml. Ten (55%) of the samples, assessed by the Amplicor HCV Monitor assay showed a mean viral titre of (1.13+/-0.75)x10(6) copies/ml, which was lower than the other two tests. The competitive PCR method and real time PCR could amplify all prevalent genotypes. This in-house quantitative competitive RT-PCR method is simple, cheap, reproducible and useful for estimation of HCV RNA load.

Quantification of hepatitis C virus (HCV) in liver specimens and sera from patients with human immunodeficiency virus coinfection by using the Versant HCV RNA 3.0 (branched DNA-based) DNA assay

The new generation assay Versant HCV RNA 3.0v (Bayer Diagnostics) was evaluated to quantify hepatitis C virus (HCV) RNA levels in liver biopsy specimens from patients with HCV and human immunodeficiency virus (HIV) coinfection. A total of 25 liver biopsies and sera collected at the time of liver biopsy were used. The efficiency of HCV RNA recovery from spiked samples was between 38.6 and 50.7%, and reproducible measurements of viral load were observed (the intra- and interrun coefficients of variation were 0.5 to 13% and 3.5 to 24.7%, respectively), with good specificity and sensitivity. Linearity was evaluated in the range of 96,154 to 769 IU/ micro g by using a serially diluted high-titer sample. Coinfected patients had high HCV RNA viral loads in serum and liver (498,471 IU/ml and 231,495 IU/ micro g, respectively), and both levels were correlated (r = 0.63; P < 0.01). The amount of hepatic HCV RNA was significantly higher among patients with genotype 1 than among patients with genotype 3 (P < 0.01). The virological end-of-treatment response in the serum was associated with a lower pretreatment intrahepatic HCV viral load (P = 0.03). The new version of b-DNA is a sensitive, specific, and reproducible method for quantitating HCV RNA in the liver. Given its positive analytical performance, the assay will be used to evaluate the HCV RNA levels in the serum and liver during follow-up of patients treated with an anti-HCV therapeutic regimen.

Variation of hepatitis C virus load, hypervariable region 1 quasispecies and CD81 hepatocyte expression in hepatocellular carcinoma and adjacent non-cancerous liver

Hepatitis C virus (HCV) infection is etiologically associated with the development of hepatocellular carcinoma (HCC) worldwide. HCV has been reported to exist and replicate in both HCC and adjacent non-cancerous liver tissue, but limited information was available on HCV viral load and quasispecies composition in HCC relative to adjacent non-cancerous hepatocytes. Previous study has also suggested CD81, a surface hepatocyte protein, as a receptor for HCV. To clarify the above, HCV-RNA and CD81-RNA titers in 20 paired hepatectomized liver and serum were quantitatively measured by chemiluminescent RT-cPCR. Hypervariable region 1 (HVR-1) variations of parallel specimens were analyzed after subcloning in 6 patients. HCV-RNA levels in serum and non-cancerous liver were markedly higher for HCV genotype 1 than genotype non-1. HCV levels were markedly higher in non-cancerous liver than in HCC (P = 0.001) in a genotype-independent manner, with a mean ratio of 56:1 for non-cancerous tissue to HCC. Both non-cancerous and HCC tissues had the same level of CD81-RNA expression, which was not linked to HCV load. HCV-RNA quantity in both HCC and non-cancerous liver correlated with the number of HVR-1 quasispecies in the tissue, and distinct HVR-1 subclones existed.

Transmission of HCV to a chimpanzee using virus particles produced in an RNA-transfected HepG2 cell culture

It was demonstrated previously that HepG2 cells produce negative strand RNA and virus-like particles after transfection with RNA transcribed from a full-length hepatitis C virus (HCV) cDNA clone [Dash et al. (1997) American Journal of Pathology, 151:363-373]. To determine in vivo infectivity of these in vitro synthesized viral particles, a chimpanzee was inoculated intravenously with HCV derived from HepG2 cells. The infected chimpanzee was examined serially for elevation of liver enzymes, for the presence of HCV RNA in the serum by reverse transcription nested polymerase chain reaction (RT-PCR), anti-HCV antibodies in the serum, and inflammation in the liver. The chimpanzee developed elevated levels of liver enzymes after the second week, but the levels fluctuated over a 10-week period. HCV RNA was detected in the serum of the chimpanzee at the second, seventh and ninth weeks after inoculation, and remained positive up to 25 weeks. Liver biopsies at Weeks 18 and 19 revealed of mild inflammation. Nucleotide sequence analysis of HCV recovered from the infected chimpanzee at the second and ninth weeks showed 100% sequence homology with the clone used for transfection studies. Serum anti-HCV antibodies were not detected by EIA during the 25 weeks follow-up period. These results suggest that intravenous administration of the virus-like particles derived from RNA-transfected HepG2 cells are infectious, and therefore, the pMO9.6-T7 clone is an infectious clone. These results provide new information that in vitro synthesized HCV particles produced from full-length HCV clone can cause infection in a chimpanzee. This study will facilitate the use of innovative approaches to the study of assembly of HCV particles and mechanisms of virus infectivity in cell culture.

The application of the bioelectric recognition assay for the detection of human and plant viruses: definition of operational parameters

The bioelectric recognition assay (BERA) is a novel biosensory method based on a unique combination of a group of cells, their immobilization in a matrix that preserves their physiological functions and the expression of the cell interaction with viruses as a change in electrical properties. A BERA sensor consists of an electroconductive, tube-like probe containing components of immobilized cells in a gel matrix. Cells are selected to specifically interact with the virus under detection. In this way, when a positive sample is added to the probe, a characteristic, 'signature-like' change in electrical potential occurs upon contact between the virus and the gel matrix. In the present study, we demonstrate that BERA can be used for the detection of viruses in humans (hepatitis C virus) and plants (tobacco and cucumber viruses) in a remarkably specific, rapid (1-2 min), reproducible and cost-efficient fashion. The sensitivity of the virus detection with BERA (0.1 ng) is equal or even better than with advanced immunological, cytological and molecular techniques, such as the reverse transcription polymerase chain reaction. Moreover, a good storability of the sensors can be achieved without affecting their performance. The potential use of portable BERA biosensors in medicine, for mass screening purposes, as well as for the detection of biological warfare agents without prior knowledge of a specific receptor-molecule interaction is discussed.