Evaluation of the Abbott RealTime HCV genotype II plus RUO (PLUS) assay with reference to core and NS5B sequencing

Comparison of diagnostic performance among Abbott RealTime HCV Genotyping II, Abbott HCV Genotype plus RUO, and Roche Cobas HCV Genotyping assays for hepatitis C virus genotyping

Comparison of diagnostic accuracy for commercial hepatitis C virus (HCV) genotyping (Abbott RealTime HCV Genotyping II, Roche Cobas Genotyping) and investigational Abbott HCV Genotype plus RUO assays designed to discriminate genotype (GT)-1a, 1b or 6 in cases of ambiguous GT from the Abbott commercial assay remains limited. 743 HCV-viremic samples were subjected to analysis using Abbott and Roche commercial as well as Abbott HCV Genotype plus RUO assays. Next-generation sequencing (NGS) targeting core region was employed as the reference standard. Diagnostic accuracy was reported as the number of participants (percentages) along with 95% confidence intervals (CIs). Using NGS, 741 samples (99.7%) yielded valid genotyping results. The diagnostic accuracies were 97.6% (95% CI: 96.1%-98.5%) and 95.3% (95% CI: 93.4%-96.6%) using Abbott and Roche commercial assays (p = 0.0174). Abbott commercial assay accurately diagnosed HCV GT-6a and 6w, whereas Roche commercial assay accurately diagnosed HCV GT-6a. Both assays demonstrated low accuracies for HCV GT-6b, 6e, 6g, and 6n. Abbott HCV Genotype plus RUO assay discriminated 13 of the 14 samples (92.9%; 95% CI: 64.2%-99.6%) that yielded ambiguous GT. Both assays were capable of diagnosing mixed HCV infections when the minor genotype comprised >8.4% of the viral load. The diagnostic performance of commercial HCV genotyping assays is commendable. Abbott assay demonstrated superior performance compared to Roche assay in diagnosing HCV GT-6. Abbott HCV Genotype plus RUO assay aids in discriminating ambiguous GT. Both commercial assays are proficient in diagnosing mixed HCV infections at a cut-off viral load of 8.4% in minor genotype.

Genetic history of hepatitis C virus genotype 6 in Taiwan

Unlike hepatitis C virus (HCV) genotype (GT) 6, which is widely circulated in Southeast Asia and South China, GT 6 was not reported in Taiwan until 2006. GT 1b and 2a, also known as global HCV subtypes, have been reported as major GTs circulating in Taiwan. Because of improvement in genotyping kits and sequencing techniques for the subtyping of HCV, an increasing number of GT 6 subtypes have been reported, especially subtype 6a among intravenous drug users with human immunodeficiency virus infection after an outbreak since 2003. Thus, HCV GT 6 infection is regarded to be closely associated with injection drug use. However, recently, we found an unexpectedly high GT 6 prevalence in the general population in Tainan, southern Taiwan. Most of these GT 6 samples belonged to a putative novel subtype closely related to 6g and 6w instead of 6a. Phylogenetic analyses indicated that this putative 6g-related novel subtype and 6w could be indigenous in southern Taiwan for centuries. Southern Taiwan could be the origin of HCV subtype 6w. This finding might change the perspective of HCV epidemiology in Taiwan.

Hepatitis C Virus Subtypes Novel 6g-Related Subtype and 6w Could Be Indigenous in Southern Taiwan with Characteristic Geographic Distribution

Hepatitis C virus (HCV) genotype (GT) 6 is the most genetically diverse GT and mainly distributed in Southeast Asia and south China but not Taiwan. Earlier studies showed the major HCV GTs in Taiwan were GT 1b and 2 with very rare GT 6 except in injection drug users (IDUs), and subtype 6a is the main GT 6 subtype among IDUs. Recently, we reported a much higher prevalence (18.3%) of GT 6 in Tainan City, southern Taiwan. This study was designed to clarify the subtypes of GT 6 in this endemic area. A total of 3022 (1343 men and 1679 women) HCV viremic patients were enrolled. Subtypes of GT 6 were determined by sequencing of core/E1 and nonstructural protein 5B in 322 of 518 GT 6 patients. The overall GT 6 prevalence rate was 17.1% (518/3022), with higher prevalence districts (>25%) located in northern Tainan. A novel 6g-related subtype is the most prevalent subtype (81.0%), followed by 6w (10.8%), 6a (7.5%), and 6n (0.7%). The high GT 6 prevalence in Tainan was mainly due to a novel 6g-related subtype and 6w. These two subtypes could be indigenous in Tainan with characteristic geographic distribution.

The performance of HCV GT plus RUO reagent in determining Hepatitis C virus genotypes in Taiwan

Background and aims

Hepatitis C virus (HCV) genotyping is a pivotal tool for epidemiological investigation, guiding management and antiviral treatment. Challenge existed in identifying subtypes of genotype-1 (G-1) and genotype (GT) of indeterminate. Recently, the Abbott HCV RealTime Genotype Plus RUO assay (HCV GT Plus) has been developed aiming to overcome the limitations. We aimed to evaluate the performance of the assay compared with 5’ UTR sequencing in clinical samples.

Materials and methods

Eligible individuals were treatment chronic hepatitis C patients that were enrolled consecutively in a medical center and two core regional hospitals in southern Taiwan from Oct 2017 through Aug 2018. The patient with genotype 1 without subtype and indeterminate previously genotyped by Abbott RealTime HCV GT II will further determinate by Abbott HCV RealTime HCV GT Plus. All of the genotype results were validated by 5' UTR sequencing as a reference standard.

Results

A total of 100 viremic CHC patients were recruited, including 63 G-1 patients (male: 28), and 37 patients (male: 15) of indeterminate genotyped by Abbott RealTime HCV GT II assay (HCV GT II), respectively. The detection rate of 63 GT1 samples without subtype were 93.7% (59/63), 37 indeterminate samples without genotype were 62.2 (23/37) by HCV GT Plus. 5' UTR sequencing confirmed HCV GT Plus characterized results for 84.7% (50/59) of type1, with 100% (4/4), 82.8 (24/29) and 84.6% (22/26) for 1a, 1b and type6; 65.2% (15/23) of indeterminate with 100% (3/3) and 60% (12/20) for 1b and type 6 samples, respectively.

Conclusions

The Abbott RealTime HCV GT Plus RUO assay provides additional performance in GT detection.

High prevalence of genotype 6 hepatitis C virus infection in Southern Taiwan using Abbott genotype assays

BACKGROUND/PURPOSE

Abbott RealTime Genotype II assay can effectively identify hepatitis C virus (HCV) genotypes (GTs), but some GT 6 subtypes might not be differentiated from GT 1. Abbott RealTime Genotype II PLUS and sequencing might be needed to resolve these ambiguous results. Unlike the high prevalence of GT 6 in Southeast Asia, GT 6 had rarely been reported in Taiwan except in intravenous drug abusers (IDU). But the prevalence of GT 6 in Taiwan might be underestimated. We conducted this study to determine the GTs in a HCV endemic area in Southern Taiwan.

METHODS

A total of 1147 patients with hepatitis C viremia for direct acting antivirals (DAA) treatment at the Chi Mei medical system in Tainan were enrolled. Genotype was determined using a working flow consisted of Abbott GT II, PLUS assays and 5' untranslated region (5' UTR)/core sequencing.

RESULTS

Among the 1147 patients, 883 (77.0%) obtained GT results by GT II, 264 (23.0%) samples with ambiguous results by GT II assay received further tests, including 194 (73.5%) with PLUS assay and 70 (26.5%) with 5'UTR/core sequencing. Nearly three-quarters (73.5%) of ambiguous results by GT II assay were GT 6. Overall, 18.3% of samples were GT 6. Phylogenetic study of 11 samples of GT 6 subtypes showed 7 (63.6%) were 6 g.

CONCLUSION

GT 6 is the major factor for high ambiguous rate by GT II. Unexpected high prevalence of GT 6 (18.3%) in Southern Taiwan, especially subtype 6 g, closely related to Indonesian strains, is first reported.

Infection with multiple hepatitis C virus genotypes detected using commercial tests should be confirmed using next generation sequencing

Current HCV genotyping methods may have some limitations in detecting mixed infections. We aimed to determine the accuracy of genotyping and the detection of mixed-genotype infections using the Abbott-RealTime HCV Genotype II assay (Abbott-RT-PCR) in comparison with a Roche-Next Generation Sequencing assay (Roche-NGS). Plasma samples collected from 139 HCV-infected patients tested with Abbott-RT-PCR, 114 with single genotype (GT) and 25 with mixed GTs were genotyped using Roche-NGS. Roche-NGS confirmed all single GTs obtained with Abbott-RT-PCR. One case of Abbott GT 4 was found as GT 1a using Roche-NGS. Genotype 5 was confirmed using Roche-NGS in 75% cases (3 out of 4 cases). Twenty-five patients were identified as having mixed HCVinfections using Abbott-RT-PCR. The concordance between Abbott-RT-PCR and Roche-NGS was 76% (19 out of 25 cases). Three mixed-GT infections identified with the Abbott assay (two (1b + 4); one (1a + 3)) were reported as pure 1b using Roche-NGS. Very divergent results were found for the other three samples. When compared to Roche-NGS, Abbott-RT-PCR has performed excellently for the determination of patients infected with single GTs. For patients that are categorized as having a mixed infection using Abbott-RT-PCR, we recommend an NGS assay as a confirmation test.

Clinical evaluation of IntelliPlexTM HCV genotyping kit for hepatitis C virus genotyping

Genotyping of the hepatitis C virus (HCV) is crucial for determining the most efficient anti-viral therapy. The clinical sensitivity and specificity of the IntelliPlex^TM HCV Genotyping Kit was determined by comparing the assay results of 307 specimens with the results obtained by Sanger sequencing. Out of 202 HCV-positive specimens tested, 8 samples yielded discrepant results between the IntelliPlex HCV Genotyping Kit and Sanger sequencing. For 5 of these discrepant samples, the IntelliPlex HCV Genotyping Kit classified the correct genotype but failed to show the same single or dual infected status as determined by Sanger sequencing. A total of 105 samples which tested negative for HCV by In-Vitro-Diagnostics (IVD)-approved viral load assay tested negative for HCV by the IntelliPlex HCV Genotyping Kit. The IntelliPlex HCV Genotyping Kit has a clinical specificity of 100% and a clinical sensitivity of 96.9% and is suited to be used in clinical laboratories to genotype HCV.

Reliable resolution of ambiguous hepatitis C virus genotype 1 results with the Abbott HCV Genotype Plus RUO assay

Accurate subtyping of hepatitis C virus genotype 1 (HCV-1) remains clinically and epidemiologically relevant. The Abbott HCV Genotype Plus RUO (GT Plus) assay, targeting the core region, was evaluated as a reflex test to resolve ambiguous HCV-1 results in a challenging sample collection. 198 HCV-1 specimens were analysed with GT Plus (38 specimens with and 160 without subtype assigned by the Abbott RealTime Genotype II (GT II) assay targeting the 5’NC and NS5B regions). Sanger sequencing of the core and/or NS5B regions were performed in 127 specimens without subtype assignment by GT II, with “not detected” results by GT Plus, or with mixed genotypes/subtypes. The remaining GT Plus results were compared to LiPA 2.0 (n = 45) or just to GT II results if concordant (n = 26). GT Plus successfully assigned the subtype in 142/160 (88.8%) samples. “Not detected” results indicated other HCV-1 subtypes/genotypes or mismatches in the core region in subtype 1b. The subtyping concordance between GT Plus and either sequencing or LiPA was 98.6% (140/142). Therefore, combined use of GT II and GT Plus assays represents a reliable and simple approach which considerably reduced the number of ambiguous HCV-1 results and enabled a successful subtyping of 98.9% of all HCV-1 samples.

Real-world effectiveness and safety of sofosbuvir and ledipasvir with or without ribavirin for patients with hepatitis C virus genotype 1 infection in Taiwan

Background

The real-world data for the effectiveness and safety of sofosbuvir/ledipasvir (SOF/LDV) with or without ribavirin (RBV) in patients with hepatitis C virus genotype 1 (HCV-1) infection remain limited in Taiwan.

Methods

A total of 273 chronic HCV-1 patients receiving 8, 12, or 24 weeks of SOF/LDV with or without RBV were enrolled. The sustained virologic response rate at week 12 off-therapy (SVR₁₂) by evaluable population (EP) and per-protocol population (PP) were assessed for effectiveness. The treatment discontinuation rate due to adverse events (AEs) and serious AE rate were assessed for safety. Baseline patient characteristics and on-treatment HCV viral kinetics associated with SVR₁₂ were analyzed.

Results

The SVR₁₂ rates by EP and PP analyses were 96.7% (95% confidence interval [CI]: 93.9%-98.3%) and 97.5% (95% CI: 94.8%-98.8%), respectively. The rates of treatment discontinuation due to AE and serious AE were 0.4% and 4.4%, respectively. Seven patients with true virologic failure were relapsers. In 2 patients who were lost-to follow-up, one expired at treatment week 3 due to pneumonia which was considered not related to treatment, and one declined follow-up at off-therapy week 4. The SVR₁₂ rates were comparable in terms of baseline patient characteristics and viral decline at week 4 of treatment.

Conclusions

SOF/LDV with or without RBV for 8–24 weeks is well tolerated and achieves a high SVR₁₂ rate in patients with HCV-1 infection in Taiwan.

Indeterminate genotypes of hepatitis C virus by the Abbott RealTime HCV Genotype II assay in Morocco. About eight cases resolved by a sequencing method

The early detection and genotyping of the hepatitis C virus (HCV) are important in the management of this infection. The genotype is the major factor influencing treatment decisions. That's why it is necessary to use fast and accurate methods in its determination. This study reports, over a period of 3 years (from May 2012 to July 2015), the percentage of indeterminate genotypes by the Abbott RealTime HCV Genotype II test and their results using a sequencing technique. Of 309 samples of 309 patients tested, 11 were indeterminate (4.4%). There were three cases of cross-reactivity (1b/4 in one case, 2/5 in two cases) and a possible co-infection 1 + 4. Among those indeterminate genotypes, cross-reactivities and co-infections, ten samples were tested by sequencing. The results were for four of them a 1d subtype, five were a 2i subtype and one was a 2l subtype. These results support the thesis of complementarity between the two methods: genotyping for the detection of mixed reactions and sequencing for resolving indeterminate cases by genotyping.

A novel standardized deep sequencing-based assay for hepatitis C virus genotype determination

Hepatitis C virus (HCV) genotype and subtype (1a/1b) identification is needed to tailor anti-HCV therapy. Currently available methods accurately identify the genotype and differentiate subtypes 1a from 1b. However, these assays have not been designed to identify other HCV subtypes, nor to recognize mixed genotype/subtype infections, emphasizing the need for a high-resolution system based on phylogenetic analysis of reads obtained by deep sequencing of a relevant genome region. The aim of this study was to evaluate the performance of the Sentosa SQ HCV Genotyping Assay, a novel deep sequencing-based assay targeting the HCV nonstructural 5B (NS5B) region, in clinical samples from patients with an indication for anti-HCV therapy. A high concordance rate with Sanger sequencing of the NS5B region, the reference method, was found for genotype 1 to 6 determination, 1a/1b subtype identification, and genotype 4, 5 and 6 subtyping. Discrepancies were seen essentially for HCV genotype 2 subtyping. Overall, the performance of the deep sequencing-based assay in generating the genotypes/subtype information needed to tailor anti-HCV treatment was adequate in this study. Further improvements, such as a longer NS5B fragment analyzed and enriching the database of reference prototype strains used for subtype assignment would make it a method of choice for HCV genotyping and subtyping for future clinical practice and research.

Utility of the Abbott RealTime HCV Genotype Plus RUO assay used in combination with the Abbott RealTime HCV Genotype II assay

BACKGROUND

Hepatitis virus C (HCV) genotype (GT) determination and subtype (ST) differentiation (1a versus 1b) remain important for the selection of appropriate direct-acting antiviral (DAA) therapy.

OBJECTIVES

This study is a retrospective comparison of HCV GT and ST result distribution when using the Abbott RealTime HCV Genotype II assay (HCVGT II) alone and in combination with the Abbott RealTime HCV Genotype Plus RUO assay (HCVGT Plus) for routine testing of clinical serum specimens at a reference laboratory.

STUDY DESIGN

HCVGT II results of specimens tested from June 2014 through January 2016 (period 1) were compared with combined results from HCVGT II and HCVGT Plus (HCVGT II/Plus) performed from January 2016 through January 2017 (period 2).

RESULTS

A total of 44,127 and 25,361 specimens were tested during periods 1 and 2, respectively. Use of HCVGT II/Plus significantly reduced the frequency of GT 1 results without ST (0.4%) when compared to preliminary HCVGT II results during period 2 (5.3%; p < 0.01) and final HCVGT II results in period 1 (5.5%; p < 0.01). HCVGT II/Plus also resulted in GT 6 reactivity in 38 specimens with results of "HCV detected" (n = 17) or GT 1 (n = 21) following initial HCVGT II testing during period 2.

CONCLUSIONS

When compared to the use of HCVGT II alone, HCVGT II/Plus significantly reduced the frequency of GT 1 without ST results observed in a large reference laboratory, while also enabling the identification of HCV GT 6.

Impact of inter-genotypic recombination and probe cross-reactivity on the performance of the Abbott RealTime HCV Genotype II assay for hepatitis C genotyping

The Abbott RealTime HCV Genotype II assay (Abbott-RT-HCV assay) is a real-time PCR based genotyping method for hepatitis C virus (HCV). This study measured the impact of inter-genotypic recombination and probe cross-reactivity on the performance of the Abbott-RT-HCV assay. 517 samples were genotyped using the Abbott-RT-HCV assay over a one-year period, 34 (6.6%) were identified as HCV genotype 1 without further subtype designation raising the possibility of inaccurate genotyping. These samples were subjected to confirmatory sequencing. 27 of these 34 (79%) samples were genotype 1b while five (15%) were genotype 6. One HCV isolate was an inter-genotypic 1a/4o recombinant. This is a novel natural HCV recombinant that has never been reported. Inter-genotypic recombination and probe cross-reactivity can affect the accuracy of the Abbott-RT-HCV assay, both of which have significant implications on antiviral regimen choice. Confirmatory sequencing of ambiguous results is crucial for accurate genotyping.