HCV Nucleic Acid Testing Research Articles

HCV RNA Quantification by a Domestic Commercial Assay: A Case Study among People Who Inject Drugs in Vietnam.

The desired performance of nucleic acid testing (NAT) may vary if used for disease diagnosis or for the evaluation of the therapeutic efficacy of a treatment, although in most cases, the same assay is used. However, these tests may not be affordable in many situations including in low/middle income countries that in response have developed domestic assays. Given the example of HCV NAT among people who inject drugs in Vietnam, we aimed at evaluating a domestic assay versus an FDA- and CE-approved assay. This cross-evaluation revealed that (i) the domestic assay had a poorer sensitivity with a threshold of detection above 104 IU/mL, and (ii) the FDA-approved assay had a percentage of false negative results close to 1%. Together, in the present study, the domestic assay had a performance compatible with diagnosis purposes (given that this population was 70% HCV seropositive) but not compatible with HCV treatment monitoring (given that treatment failures are rare and the observed viremia frequently below the threshold of detection). This study highlights the need for a proper evaluation of HCV RNA domestic assays in order to efficiently contribute to the WHO HCV elimination target by 2030.

Re-assessing the risk of undetected HBV, HCV and HIV in deceased tissue and living surgical bone donors in England.

Testing of living surgical bone and deceased tissue donors by NHS Blood and Transplant (NHSBT) has included individual donation (ID) nucleic acid testing (NAT) for HBV, HCV and HIV since 2008. Here, the well-established window period methodology was used to estimate residual risk (RR). Prevalence of viral markers was calculated among both tissue donor populations. Incidence was derived by adjusting incidence among new blood donors by the prevalence ratio for tissue and new blood donors. Residual risk (RR) was calculated as the product of incidence and duration of WP for single donor HBV NAT at 0.058years (21days), HCV NAT at 0.008years (3days) and HIV NAT at 0.014 (5days). Between 2013 and 2017, 7886 living surgical bone donors were tested, 16 were positive for markers of HBV, HCV and HIV. HCV had the highest prevalence at 114/100,000 donors. Incidence and RR was highest for HBV at 3.55/100,000-person years and 0.32/100,000 donors (95% CI 0.11/100,000-1.42/100,000). Among 9751 deceased tissue donors tested, 22 were positive for viral markers. HBV had highest prevalence at 174/100,000 donors, and the highest incidence and RR at 8.12/100,000 person years and 0.74/100,000 donors (95% CI 0.08/100,000-2.99/100,000). Using ID NAT, RR of not detecting a HBV, HCV and HIV WP donation among tissue donors is less than 1/100,000 donors. These estimates provide a good starting point for discussing potential risks of viral transmission through tissue transplant with patients.

Advances in studies of HCV nucleic acid testing for clinical diagnosis

HCV infection is of global concern with the characteristic of insidious onset. Laboratory testing stands indispensably for clinical diagnosis with antibody assay and nucleic acid testing the main methods being adopted. For early detection and diagnosis of HCV infection, it is important to choose the best detection method and diagnostic strategy. This paper reviews the HCV nucleic acid testing methods, as well as performance evaluation of reagents and current strategies.

Cardiac transplantation from non-viremic hepatitis C donors.

Hepatitis C (HCV) donors are rarely used for cardiac transplantation due to historically poor outcomes. In 2015, nucleic acid testing (NAT) for viral load was added to the routine work-up of organ donors, allowing for the distinction between subjects who remain viremic (HCV Ab+/NAT+) and those who have cleared HCV and are no longer viremic (HCV Ab+/NAT-). The American Society of Transplantation recently recommended that HCV Ab+/NAT- donors be considered non-infectious and safe for transplantation. We present our initial experience with such donors. All patients were counseled regarding donor HCV antibody (Ab) and NAT. Transplant recipients were tested post-transplant at 1 week and at 1, 3, and 6 months for HCV seropositivity and viremia. We also analyzed the UNOS database to determine the potential impact of widespread acceptance of HCV Ab+/NAT- organs. Fourteen HCV Ab‒ subjects received hearts from HCV Ab+/NAT- donors in 2017. Over a median follow-up of 256 (192 to 377) days, 3 patients developed a reactive HCV Ab, yet none had a detectable HCV viral load during prospective monitoring at any time. Analysis of the UNOS database for the calendar year 2016 revealed that only 7 (3%) of 220 HCV Ab+/NAT- donors were accepted for heart transplantation. We have demonstrated the feasibility of utilizing HCV Ab+/NAT- donors for cardiac transplantation without recipient infection. A small percentage of recipients developed HCV Ab without evidence of viremia, possibly consistent with a biological false reactive test, as has been seen in other settings. Large-scale validation of our data may have a significant impact on transplantation rates.

Early Outcomes Using Hepatitis C-Positive Donors for Cardiac Transplantation in the Era of Effective Direct-Acting Antiviral Treatments

Introduction: The shortage of suitable donor hearts for cardiac transplantation contributes to wait list mortality. Given this need, and the favorable drug profiles and efficacy of current agents used to treat Hepatitis C (HCV), our institution recently piloted transplantation of selected patients using HCV-positive donors. Methods: Between September 2016 and March 2017, 11 HCV-naïve patients and 1 patient with a history of HCV that was treated and cured prior to listing, underwent heart transplantation from HCV-positive donors. Patients were treated per our standard immunosuppression protocol. Following transplant, patients were referred to hepatology for monitoring and treatment. Data collection and analysis were performed after obtaining informed patient consent and IRB approval. Results: Baseline characteristics: Mean age of recipients at time of transplant was 52.7 years (SD 9.9). Eight patients (66%) were male, eight patients (66%) were Caucasian, and eight patients (66%) were on left ventricular assist device support. Mean age of organ donors was 30.3 years (SD 4.3). All donors tested positive for antibodies to HCV; only ten had positive HCV nucleic acid testing. Time to transplant: Recipients' total wait list time varied prior to them consenting to receive an HCV-positive heart. Following consent, time to transplant was short (median 2.5 days [IQR 1.2–17]), even for patients with unfavorable blood groups, elevated panel reactive antibodies, or lower listing status. Hepatitis C testing and treatment: Nine of 12 patients (75%) who received hearts from HCV-positive donors developed HCV viremia. Three patients remain disease-free. Of the nine patients who developed HCV, seven patients have initiated or completed antiviral treatment, with a fixed dose combination of either sofosbuvir/ledipasvir or sofosbuvir/velpatasvir. All treated patients have undetectable viral loads (mean time from treatment initiation to viral suppression 53.3 days [SD 28.8]). The two remaining patients with HCV will soon initiate treatment. Tolerability and adverse events: Among patients who initiated HCV treatment and demonstrated suppression of viremia, one patient died due to a pulmonary embolism and one patient developed echocardiographic graft dysfunction of unclear etiology, which resolved spontaneously upon subsequent imaging. Conclusions: In the era of highly effective HCV pharmacotherapy, the use of HCV-positive donors represents a potential approach to safely expand the donor pool. This report represents the first and largest series to date and demonstrates that HCV treatment leads to rapid viral suppression early after transplant, despite immunosuppression. Additional follow-up is needed to elucidate long-term outcomes and assess for sustained virologic response.

Deceased Organ Donor Screening for HIV, Hepatitis B, and Hepatitis C Viruses: A Survey of Organ Procurement Organization Practices

Although Organ Procurement and Transplantation Network (OPTN) policy requires that all potential deceased organ donors are screened for human immunodeficiency (HIV), hepatitis B (HBV) and hepatitis C (HCV) viruses by serology, no current policy requires the use of nucleic acid testing (NAT) for organ donor screening. An electronic survey was sent to 58 organ procurement organizations (OPO) in the United States to assess current screening practices of potential deceased organ donors. Fifty-seven responses were collected for data analysis; not all respondents answered all questions. All OPOs performed required HIV, HBV and HCV serology screening and 48 (84%) performed confirmatory testing for seropositive donors. Ninety-eight percent, 75% and 97% of OPOs performed prospective HIV, HBV and HCV NAT, respectively. Fifty-two percent and 47% used a transcription-mediated amplification assay for HIV and HCV NAT, respectively. Of the 56 respondents that performed HIV NAT and 55 respondents that performed HCV NAT, 39 tested all donors. Seventeen (32%) OPOs performed confirmatory testing for all HIV-positive NAT results, and 15 (27%) OPOs performed confirmatory testing for all HCV-positive NAT results. Since 2008, the number of OPOs performing NAT has increased and more OPOs are testing all donors.

Changing strategies for hepatitis C testing

Recent approvals of direct-acting, orally delivered pharmaceuticals for the treatment of patients with infection by HCV and of a point-of-care assay for community screening of HCV infection have generated impetus to widen the identification of HCV-infected individuals. Diagnosis of HCV infection is, however, still based on the detection of anti-HCV immunoglobulin G. As treatment is intended for individuals with current infection, testing for evidence of infection would need to centre on the detection of HCV viraemia. Minimizing the complexity and costs associated with HCV nucleic acid testing and speeding the development and validation of HCV antigen assays expedite the identification of HCV-viraemic individuals. Establishing means to diagnose recent HCV infection and to engage in surveillance of drug-resistant HCV are also apposite. Successful implementation of these various measures brightens prospects for the eventual elimination of HCV.

Problems and solutions on standardization of reagents for detection of HBV and HCV infection

Compared with commercial reagents manufactured by foreign companies for detection of HBV and HCV infection, domestic reagents have poorer performance because of the over-pursuit of easy operation and lack of metrological traceability in quantitative measurement. If two-step sandwich ELISA model and multiple monoclonal coating antibodies were used, false-negative results caused by the hook-effect and HBsAg mutant would be avoided. Moreover, sufficient incubation time in each step would improve the detection-limit of the reagents. By replacing the boiling lysis with nucleic acid purification in sample preparation and increasing the sample volume of nucleic acid purification and amplification detection could improve the detection-limit and reproducibility of HBV and HCV nucleic acid testing. The use of internal control could effectively monitor the of false negative results as well Application of international or national reference materials for metrological traceability of calibrators in reagents also plays an important role in assuring result concordance among different commercial reagent kits, methods and clinical laboratories. Key words: Hepatitis B virus; Hepacivirus; Polymerase chain reaction; Indicators and reagents; Reference standards

Provider Utilization of High-Risk Donor Organs and Nucleic Acid Testing: Results of Two National Surveys

Fears of infectious transmission from CDC high-risk donors (HRDs) remain a significant disincentive, and the potential for human immunodeficiency virus/hepatitis C virus (HIV/HCV) nucleic acid testing (NAT) to allay these fears remains unstudied. We hypothesized that NAT, which narrows the window period between infection and detectability compared to the standard ELISA, might lead to increased provider willingness to use HRDs. Between January and April 2008, we performed two national surveys: one of current NAT practice among organ procurement organizations (OPOs); a second of HRD use among transplant surgeons. Surgeons who reported accepting 10% or more offers for a given HRD behavior and organ type were classified as 'high utilizers' of that subgroup. We built hierarchical models to examine associations between OPO NAT performance and provider utilization. Providers who ranked medical risks of HIV or HCV as important disincentives to HRD use had significantly lower odds of being high utilizers (HIV odds ratio 0.22, HCV odds ratio 0.41, p < 0.005). Furthermore, both HIV and HCV NAT performance were associated with significantly higher odds of being high utilizers (HIV odds ratio 1.58, HCV 2.69, p < 0.005). The demonstrated associations between OPO NAT performance and high provider utilization of HRDs should be considered in the ongoing debate about NAT in transplantation.

Prevalence and Estimated Incidence of Blood-Borne Viral Pathogen Infection in Organ and Tissue Donors from Northern Alberta

To determine the potential safety benefit of introducing nucleic acid testing (NAT) in tissue and organ donors, the risk of virus transmission was examined in a Canadian population. Anonymous data on Northern Alberta tissue and organ donors from 1998 to 2004 were used to determine the seroprevalence and estimate the seroincidence and residual risk of HIV, HBV, HCV and HTLV infection. Of the 3372 donors identified, 71.1% were surgical bone, 13.2% were living organ and 15.6% were deceased organ/tissue donors. Seroprevalence was: HIV 0.00%, HBV 0.09%, HCV 0.48% and HTLV 0.03%. Incidence (/100,000 p-yrs) and residual risks (/100,000 donors) could only be estimated for HBV (24.2 and 3.9) and HCV (11.2 and 2.2). Risk estimates were higher for deceased donors than surgical bone donors. HCV had the highest prevalence and HBV had the highest estimated incidence. HIV and HTLV risks were extremely low precluding accurate quantification. In this region of low overall viral prevalence, HCV NAT would be most effective in deceased organ donors. In surgical bone donors the cost of implementing NAT is high without significant added safety benefit.

HCV core antigen detection in seropositive samples

Detection of antibodies to HCV is typically the primary test utilized to identify HCV-infected individuals. Seropositive individuals may then be tested for HCV RNA by nucleic acid testing (NAT) to determine if the individual is actively infected with HCV. In addition, NAT assays that are based on quantitation of HCV RNA copies/ml, are utilized to determine the effectiveness of antiviral therapy. Over the last several years, HCV core antigen tests have been developed that have shown utility both for the identifying active HCV infection and for monitoring antiviral therapy. Although these assays are relatively simple and rapid, the HCV core antigen tests have not been widely accepted mostly due to their lack of sensitivity. Recently developed assays have shown improved sensitivity, and may represent an alternative or adjunct to HCV NAT both for identifying active HCV infection and for monitoring antiviral therapy. J. Med. Virol. 79:S52–S53, 2007. © 2007 Wiley-Liss, Inc.

Characterization of HBV DNA+/HBsAg− blood donors in Poland identified by triplex NAT

Nucleic acid testing (NAT) for hepatitis B virus (HBV) has been performed in Poland since 2005 on samples seronegative for hepatitis B surface antigen (HBsAg), anti-hepatitis C virus (anti-HCV), and anti-human immunodeficiency virus (anti-HIV). Tools included 24-donation pool testing (PT) using Cobas Amplicor or in individual donations (ID) by Procleix Ultrio. Seven of 761,666 (1:108,800) and 21/250,191 (1:11,900) HBV DNA-positive donations were identified and confirmed by alternative methods. HBV DNA load ranged between 11.6 and 4.6 x 10(4) IU/mL in 11 samples and could not be quantified in 17 samples. HBV genotypes A (56%) and D (4%) were found. The analysis of combined results from index, follow-up, and look-back samples identified four groups: (1) Two cases tested HBsAg positive with alternative, more sensitive, assays; (2) Four cases were in the pre-seroconversion window period; (3) Eight cases had a fluctuating pattern of HBV DNA and anti-HBs detection (recovered infection); and (4) twelve cases carried anti-HBc without anti-HBs, which might correspond to either chronic or recovered "occult" HBV infection. One donor with no HBV markers in the follow-up was excluded, and another was in the window period preceding anti-HBs. HBV NAT identified more confirmed positive donors than HCV or HIV NAT, and 1:250,000 could not be detected by anti-HBc screening. Serological and molecular studies on follow-up and look-back samples are important to classify donors. In conclusion, further studies are needed to determine whether the considerably higher yield of HBV DNA detection obtained with individual donation screening improves blood safety compared with anti-HBc screening.

Trends in risk of transfusion-transmitted viral infections (HIV, HCV, HBV) in France between 1992 and 2003 and impact of nucleic acid testing (NAT)

Monitoring trends in residual risk of transfusion-transmitted viral infections is important to assess improvements in blood safety and to adapt the risk reduction policies. These trends were analysed in France over 4 periods of 3 years (1992-1994, 1995-1997, 1998-2000 and 2001-2003). The 2001-2003 estimates were compared to the results of HIV-1 and HCV NAT implemented on all blood donations in July 2001. Due to improvements in donor recruitment and selection, continuing progress in screening assays, and preventive measures taken in the community to control infections, a significant decrease was observed in residual risks for HIV, HCV and HBV between 1992 and 2003. The residual risk is currently extremely low: for the 2001-2003 period, this risk was estimated at 1 in 3.15 million donations for HIV, at 1 in 10 million for HCV and at 1 in 640,000 for HBV. Of the 6.14 million donations screened with NAT between July 2001 and December 2003 in France, 2 HIV-positive and 3 HCV-positive donations were discarded thanks to NAT, representing a yield of 1 in 3.07 million for HIV and 1 in 2.05 million for HCV. These results show the limited benefit of NAT and suggest that its cost-effectiveness is poor.