Improved detection of hepatitis C virus infection by transcription-mediated amplification technology in dialysis population

HCV Detection, Discrimination, and Genotyping Technologies

According to the World Health Organization (WHO), 71 million people were living with Hepatitis C virus (HCV) infection worldwide in 2015. Each year, about 399,000 HCV-infected people succumb to cirrhosis, hepatocellular carcinoma, and liver failure. Therefore, screening of HCV infection with simple, rapid, but highly sensitive and specific methods can help to curb the global burden on HCV healthcare. Apart from the determination of viral load/viral clearance, the identification of specific HCV genotype is also critical for successful treatment of hepatitis C. This critical review focuses on the technologies used for the detection, discrimination, and genotyping of HCV in clinical samples. This article also focuses on advantages and disadvantages of the reported methods used for HCV detection, quantification, and genotyping.

A microwell plate-based multiplex immunoassay for simultaneous quantitation of antibodies to infectious viruses

Antibodies (Abs) to disease-causing viruses in human blood are important indicators of infection status. While ELISA has been widely used to detect these Abs, a multiplex assay system for simultaneous detection of multiple Abs is still a desirable alternative method for a more efficient screening process because of the lack of multiplexing ability in ELISA. However, as all antibodies are based on immunoglobulin and recognized commonly by the same secondary antibody, it is impossible to multiplex the conventional indirect ELISA in a 96-microwell plate-based platform. To overcome this hurdle, we designed an assay consisting of two steps: capturing target Abs by specific antigens on DNA-encoded gold nanoparticles; and quantifying the target Abs by producing RNase H-mediated detection signals based on the DNA and additional RNA probes. With this newly designed method, we could simultaneously analyze three infectious disease-related Abs, anti-HIV Ab, anti-HCV Ab, and anti-HBV Ab, on the microwell-based platform. The assay performance was evaluated by comparison with ELISA. Furthermore, the accuracy and precision of the assay in a practical application was also estimated by determining the amount of target Abs in human serum solutions.

Management of hepatitis C in patients with chronic kidney disease

Hepatitis C virus (HCV) infection is highly prevalent among chronic kidney disease (CKD) subjects under hemodialysis and in kidney transplantation (KT) recipients, being an important cause of morbidity and mortality in these patients. The vast majority of HCV chronic infections in the hemodialysis setting are currently attributable to nosocomial transmission. Acute and chronic hepatitis C exhibits distinct clinical and laboratorial features, which can impact on management and treatment decisions. In hemodialysis subjects, acute infections are usually asymptomatic and anicteric; since spontaneous viral clearance is very uncommon in this context, acute infections should be treated as soon as possible. In KT recipients, the occurrence of acute hepatitis C can have a more severe course, with a rapid progression of liver fibrosis. In these patients, it is recommended to use pegylated interferon (PEG-IFN) in combination with ribavirin, with doses adjusted according to estimated glomerular filtration rate. There is no evidence suggesting that chronic hepatitis C exhibits a more aggressive course in CKD subjects under conservative management. In these subjects, indication of treatment with PEG-IFN plus ribavirin relies on the CKD stage, rate of progression of renal dysfunction and the possibility of a preemptive transplant. HCV infection has been associated with both liver disease-related deaths and cardiovascular mortality in hemodialysis patients. Among those individuals, low HCV viral loads and the phenomenon of intermittent HCV viremia are often observed, and sequential HCV RNA monitoring is needed. Despite the poor tolerability and suboptimal efficacy of antiviral therapy in CKD patients, many patients can achieve sustained virological response, which improve patient and graft outcomes. Hepatitis C eradication before KT theoretically improves survival and reduces the occurrence of chronic graft nephropathy, de novo glomerulonephritis and post-transplant diabetes mellitus.

Transcription-mediated amplification (TMA) for the assessment of viremia in hemodialysis patients with hepatitis C

The diagnosis of hepatitis C virus (HCV) infection in hemodialysis patients is difficult particularly due to the presence of intermittent viremia. The aims of this study were: (a) to determine the prevalence of intermittent viremia in hemodialysis patients with anti-HCV antibodies who tested negative for HCV RNA by PCR at the first evaluation and (b) to evaluate the contribution of the transcription-mediated amplification method (TMA) to the diagnosis of viremia in the PCR-negative samples. One hundred and six patients with anti-HCV antibodies and an initial negative result for HCV RNA by PCR were included. An additional sample was collected for a second HCV RNA test by PCR after a minimum interval of 3 months and a positive result characterized intermittent viremia. HCV RNA was investigated by TMA in the PCR-negative sample of patients with intermittent viremia, and in the most recent sample from patients with PCR-negative results in both determinations. Intermittent viremia was observed in 60/106 (57%) patients (57% men; age: 45 ± 10 years). Fifty-one of the 60 negative samples from patients with intermittent viremia and 29/46 double-negative patients were tested by TMA. This assay detected viremia in 20/51 (39%) samples of intermittent viremia and in 2/29 (7%) of double-negative samples. The results showed that intermittent viremia is frequent in hemodialysis patients who tested negative for HCV RNA by PCR. Therefore, a second HCV RNA test is necessary for all HCV RNA-negative patients. The TMA assay appears to be the best first screening test for viremia in this population.

The relationship between tumor necrosis factor-α polymorphisms and hepatitis C virus infection: a systematic review and meta-analysis

BACKGROUND AND AIMS

Hepatitis C virus (HCV) is now recognized as one of the major causes of chronic liver disease. It is also one of the most common complications in maintenance hemodialysis (HD) patients. Tumor necrosis factor (TNF)-α promoter polymorphisms are observed to modulate TNF-α levels and thought to have an effect on susceptibility to HCV infection and the virus clearance, but the results are inconsistent. In this study, a systematic review and meta-analysis of the published data was performed to evaluate the relationship between the TNF-α-238, -308 polymorphisms and HCV infection.

METHODS

A total of 15 studies published were analyzed, which were indexed from PubMed, Embase, and CNKI databases (up to December 2010). All the data were analyzed using RevMan 4.2 software. Odds ratios (OR) and confidence intervals (95% CI) were calculated by fixed or random-effects models. Heterogeneity and publication bias across the studies were also explored.

RESULTS

The data showed no significant association between TNF-α-308, -238 gene polymorphisms and the susceptibility to HCV infection in the global group (p = 0.28, p = 0.38, respectively) and the sub-groups (European, American, African, and Asian). Besides, the distributions of TNF-α-308, -238 A/G alleles were also not significantly different between the persistent infection group and the spontaneous clearance group (p = 0.64, p = 0.75, respectively).

CONCLUSION

TNF-α-238, -308 gene polymorphisms might have no effect on susceptibility to HCV infection and the virus clearance. The findings of this meta-analysis have implications in the optimal prevention of HCV in HD patients and in the guidance of future research.